PIC16LF1903T-I/MV

PIC16LF1902/3 28-Pin Flash-Based, 8-Bit CMOS MCUs with LCD Driver and XLP Technology High-Performance RISC CPU • C Compiler Optimized Architecture • Only 49 Instructions • Operating Speed: - DC – 20 MHz clock input @ 3.6V - DC – 16 MHz clock input @ 1.8V - DC – 200 ns instruction cycle • Interrupt Capability with Automatic Context Saving • 16-Level Deep Hardware Stack with Optional Overflow/Underflow Reset • Direct, Indirect and Relative Addressing modes: - Two full 16-bit File Select Registers (FSRs) - FSRs can read program and data memory Memory • Up to 7 Kbytes Self-Write/Read Flash Program Memory Addressing • Up to 256 Bytes Data Memory Addressing • High-Endurance Flash Data Memory (HEF) - 128B of nonvolatile memory - 100K erase/write cycles • Enhanced Low-Voltage Programming (LVP) • Programmable Code Protection • Power-Saving Sleep mode eXtreme Low-Power (XLP) Features (PIC16LF1902/3) • Sleep Current - 30 nA @ 1.8V, typical • Watchdog Timer Current: - 300 nA @ 1.8V, typical • Secondary Oscillator: 500 nA @ 32 kHz,1.8V, typical Analog Features • Analog-to-Digital Converter (ADC): - 10-bit resolution, up to 11 channels - Conversion available during Sleep - Dedicated ADC RC oscillator - Fixed Voltage Reference (FVR) as channel • Integrated Temperature Indicator • Voltage Reference module: - Fixed Voltage Reference (FVR) with 1.024V and 2.048V output levels Flexible Oscillator Structure • 16 MHz Internal Oscillator: - Accuracy to ± 3%, typical - Software selectable frequency range from 16 MHz to 31.25 kHz • 31 kHz Low-Power Internal Oscillator • Three External Clock modes up to 20 MHz • Two-Speed Oscillator Start-up • Low-Power RTC Implementation via LPT1OSC Special Microcontroller Features • Operating Voltage Range: - 1.8V-3.6V • Self-Programmable under Software Control • Power-on Reset (POR) • Power-up Timer (PWRT) • Low-Power Brown-Out Reset (LPBOR) • Extended Watchdog Timer (WDT) • In-Circuit Serial Programming™ (ICSP™) via Two Pins  2011-2016 Microchip Technology Inc. Peripheral Highlights • Up to 25 I/O Pins and 1 Input-only Pin: - High current 25 mA sink/source - Individually programmable weak pull-ups - Individually programmable interrupt-onchange (IOC) pins • Integrated LCD Controller: - 19 segment pins and 72 total segments - Variable clock input - Contrast control - Internal voltage reference selections • Timer0: 8-Bit Timer/Counter with 8-Bit Programmable Prescaler • Enhanced Timer1: - 16-bit timer/counter with prescaler - External Gate Input mode - Dedicated low-power 32 kHz oscillator driver DS40001455F-page 1 PIC16LF1902/3 XLP PIC16LF1902 (1) 2048 128 128 25 11 1/1 — 4 19 72(3) PIC16LF1903 (1) 4096 256 128 25 11 1/1 — 4 19 72(3) PIC16LF1904 (2) 4096 256 128 36 14 1/1 1 4 29 116 PIC16LF1906 (2) 8192 512 128 25 11 1/1 1 4 19 72(3) PIC16LF1907 (2) 8192 512 128 36 14 1/1 1 4 29 116 Note 1: I - Debugging, Integrated on Chip; H - Debugging, available using Debug Header. 2: One pin is input-only. 3: COM3 and SEG15 share a pin, so the total segments are limited to 72 for 28-pin devices. Data Sheet Index: (Unshaded devices are described in this document.) 1: DS40001455 PIC16LF1902/1903 Data Sheet, 28-Pin Flash, 8-bit Microcontrollers. 2: DS40001569 PIC16LF1904/6/7 Data Sheet, 28/40/44-Pin Flash, 8-bit Microcontrollers. Debug(1) Total Segments Segment Pins Common Pins EUSART Timers (8/16-bit) 10-bit ADC (ch) LCD I/Os(2) High-Endurance Flash (bytes) Data SRAM (bytes) Device Program Memory Flash (words) Data Sheet Index PIC16LF1902/3 Family Types H H I/H I/H I/H Y Y Y Y Y Pin Diagrams 28-PIN PDIP, SOIC, SSOP VPP/MCLR/RE3 1 28 RB7(1)/SEG13/ICSPDAT SEG12/AN0/RA0 2 27 RB6(1)/SEG14/ICSPCLK SEG7/AN1/RA1 3 26 RB5(1)/AN13/COM1 COM2/AN2/RA2 4 25 RB4(1)/AN11/COM0 SEG15/COM3/VREF+/AN3/RA3 5 24 RB3(1)/AN9/SEG26/VLCD3 SEG4/T0CKI/RA4 6 23 RB2(1)/AN8/SEG25/VLCD2 SEG5/AN4/RA5 VSS 7 22 RB1(1)/AN10/SEG24/VLCD1 21 RB0(1)/AN12/INT/SEG0 SEG2/CLKIN/RA7 9 20 VDD 10 19 VSS T1CKI/T1OSO/RC0 11 18 RC7/SEG8 T1OSI/RC1 12 17 RC6/SEG9 SEG3/RC2 13 16 RC5/SEG10 SEG6/RC3 14 15 RC4/T1G/SEG11 SEG1/CLKOUT/RA6 Note 1: 8 PIC16LF1902/3 FIGURE 1: These pins have interrupt-on-change functionality. DS40001455F-page 2  2011-2016 Microchip Technology Inc. PIC16LF1902/3 28-PIN UQFN 28 27 26 25 24 23 22 RA1/AN1/SEG7 RA0/AN0/SEG12 RE3/MCLR/VPP RB7(1)/ICSPDAT/SEG13 RB6(1)/ICSPCLK/SEG14 RB5(1)/AN13/COM1 RB4(1)/AN11/COM0 FIGURE 2: Note 1: 1 2 3 4 5 6 7 PIC16LF1902/3 21 20 19 18 17 16 15 RB3(1)/AN9/SEG26/VLCD3 RB2(1)/AN8/SEG25/VLCD2 RB1(1)/AN10/SEG24/VLCD1 RB0(1)/AN12/INT/SEG0 VDD VSS RC7/SEG8 T1CKI/T1OSO/RC0 8 T1OSI/RC1 9 SEG3/RC2 10 SEG6/RC3 11 SEG11/T1G/RC4 12 SEG10/RC5 13 SEG9/RC6 14 COM2/AN2/RA2 SEG15/COM3/VREF+/AN3/RA3 SEG4/T0CKI/RA4 SEG5/AN4/RA5 VSS SEG2/CLKIN/RA7 SEG1/CLKOUT/RA6 These pins have interrupt-on-change functionality.  2011-2016 Microchip Technology Inc. DS40001455F-page 3 PIC16LF1902/3 28-Pin PDIP/ SOIC/SSOP 28-Pin UQFN A/D Timers LCD Interrupt Pull-up Basic 28-PIN ALLOCATION TABLE (PIC16LF1902/3) I/O TABLE 1: RA0 RA1 RA2 RA3 RA4 RA5 RA6 RA7 RB0 RB1 RB2 RB3 RB4 RB5 RB6 RB7 RC0 RC1 RC2 RC3 RC4 RC5 RC6 RC7 2 3 4 5 6 7 10 9 21 22 23 24 25 26 27 28 11 12 13 14 15 16 17 18 27 28 1 2 3 4 7 6 18 19 20 21 22 23 24 25 8 9 10 11 12 13 14 15 AN0 AN1 AN2 AN3/VREF+ — AN4 — — AN12 AN10 AN8 AN9 AN11 AN13 — — — — — — — — — — — — — — T0CKI — — — — — — — — — — — T1OSO/T1CKI T1OSI — — T1G — — — SEG12 SEG7 COM2 SEG15/COM3 SEG4 SEG5 SEG1 SEG2 SEG0 VLCD1/SEG24 VLCD2/SEG25 VLCD3/SEG26 COM0 COM1 SEG14 SEG13 — — SEG3 SEG6 SEG11 SEG10 SEG9 SEG8 — — — — — — — — INT/IOC IOC IOC IOC IOC IOC IOC IOC — — — — — — — — — — — — — — — — Y Y Y Y Y Y Y Y — — — — — — — — — — — — — — CLKOUT CLKIN — — — — — — ICSPCLK ICSPDAT — — — — — — — — RE3 VDD Vss 1 20 8,19 26 17 5,16 — — — — — — — — — — — — Y(1) — — MCLR/VPP VDD VSS Note 1: Weak pull-up always enabled when MCLR is enabled, otherwise the pull-up is under user control. DS40001455F-page 4  2011-2016 Microchip Technology Inc. PIC16LF1902/3 Table of Contents 1.0 Device Overview .......................................................................................................................................................................... 6 2.0 Enhanced Mid-Range CPU ........................................................................................................................................................ 10 3.0 Memory Organization ................................................................................................................................................................. 12 4.0 Device Configuration .................................................................................................................................................................. 33 5.0 Resets ........................................................................................................................................................................................ 38 6.0 Oscillator Module........................................................................................................................................................................ 46 7.0 Interrupts .................................................................................................................................................................................... 55 8.0 Power-Down Mode (Sleep) ........................................................................................................................................................ 66 9.0 Watchdog Timer ......................................................................................................................................................................... 68 10.0 Flash Program Memory Control ................................................................................................................................................. 72 11.0 I/O Ports ..................................................................................................................................................................................... 88 12.0 Interrupt-On-Change ................................................................................................................................................................ 100 13.0 Fixed Voltage Reference (FVR) ............................................................................................................................................... 103 14.0 Temperature Indicator Module.................................................................................................................................................. 105 15.0 Analog-to-Digital Converter (ADC) Module .............................................................................................................................. 106 16.0 Timer0 Module ......................................................................................................................................................................... 119 17.0 Timer1 Module with Gate Control............................................................................................................................................. 122 18.0 Liquid Crystal Display (LCD) Driver Module............................................................................................................................. 133 19.0 In-Circuit Serial Programming™ (ICSP™) ............................................................................................................................... 166 20.0 Instruction Set Summary .......................................................................................................................................................... 169 21.0 Electrical Specifications............................................................................................................................................................ 183 22.0 DC and AC Characteristics Graphs and Charts ....................................................................................................................... 199 23.0 Development Support............................................................................................................................................................... 200 24.0 Packaging Information.............................................................................................................................................................. 204 Appendix A: Data Sheet Revision History.......................................................................................................................................... 215 The Microchip Website....................................................................................................................................................................... 216 Customer Change Notification Service .............................................................................................................................................. 216 Customer Support .............................................................................................................................................................................. 216 Product Identification System ............................................................................................................................................................ 217 TO OUR VALUED CUSTOMERS It is our intention to provide our valued customers with the best documentation possible to ensure successful use of your Microchip products. To this end, we will continue to improve our publications to better suit your needs. Our publications will be refined and enhanced as new volumes and updates are introduced. If you have any questions or comments regarding this publication, please contact the Marketing Communications Department via E-mail at docerrors@microchip.com. We welcome your feedback. Most Current Data Sheet To obtain the most up-to-date version of this data sheet, please register at our Worldwide Website at: http://www.microchip.com You can determine the version of a data sheet by examining its literature number found on the bottom outside corner of any page. The last character of the literature number is the version number, (e.g., DS30000000A is version A of document DS30000000). Errata An errata sheet, describing minor operational differences from the data sheet and recommended workarounds, may exist for current devices. As device/documentation issues become known to us, we will publish an errata sheet. The errata will specify the revision of silicon and revision of document to which it applies. To determine if an errata sheet exists for a particular device, please check with one of the following: • Microchip’s Worldwide Website; http://www.microchip.com • Your local Microchip sales office (see last page) When contacting a sales office, please specify which device, revision of silicon and data sheet (include literature number) you are using. Customer Notification System Register on our website at www.microchip.com to receive the most current information on all of our products.  2011-2016 Microchip Technology Inc. DS40001455F-page 5 PIC16LF1902/3 1.0 DEVICE OVERVIEW The PIC16LF1902/3 devices are described within this data sheet. They are available in 28-pin packages. Figure 1-1 shows a block diagram of the PIC16LF1902/3 devices. Table 1-2 shows the pinout descriptions. Reference Table 1-1 for peripherals available per device. Peripheral PIC16LF1903 DEVICE PERIPHERAL SUMMARY PIC16LF1902 TABLE 1-1: ADC ● ● Fixed Voltage Reference (FVR) ● ● LCD ● ● Temperature Indicator ● ● Timer0 ● ● Timer1 ● ● Timers DS40001455F-page 6  2011-2016 Microchip Technology Inc. PIC16LF1902/3 FIGURE 1-1: PIC16LF1902/3 BLOCK DIAGRAM Program Flash Memory RAM CLKOUT CLKIN PORTA PORTB Timing Generation PORTC CPU INTRC Oscillator Figure 2-1 PORTE MCLR Note 1: LCD Timer0 Timer1 Temp. Indicator ADC 10-Bit FVR See applicable chapters for more information on peripherals.  2011-2016 Microchip Technology Inc. DS40001455F-page 7 PIC16LF1902/3 TABLE 1-2: PIC16LF1902/3 PINOUT DESCRIPTION Name RA0/AN0/SEG12 RA1/AN1/SEG7 RA2/AN2/COM2 RA3/AN3/VREF+/COM3/SEG15 RA4/T0CKI/SEG4 RA5/AN4/SEG5 RA6/CLKOUT/SEG1 RA7/CLKIN/SEG2 RB0/AN12/INT/SEG0 RB1(1)/AN10/SEG24/VLCD1 RB2(1)/AN8/SEG25/VLCD2 RB3 (1) /AN9/SEG26/VLCD3 Function Input Type RA0 TTL AN0 AN SEG12 — RA1 TTL Output Type Description CMOS General purpose I/O. — A/D Channel 0 input. AN LCD Analog output. CMOS General purpose I/O. AN1 AN — A/D Channel 1 input. SEG7 — AN LCD Analog output. RA2 TTL AN2 AN CMOS General purpose I/O. — A/D Channel 2 input. COM2 — AN LCD Analog output. RA3 TTL CMOS General purpose I/O. AN3 AN — A/D Channel 3 input. VREF+ AN — A/D Voltage Reference input. COM3 — AN LCD Analog output. SEG15 — AN LCD Analog output. RA4 TTL T0CKI ST SEG4 — RA5 TTL CMOS General purpose I/O. — Timer0 clock input. AN LCD Analog output. CMOS General purpose I/O. AN4 AN — A/D Channel 4 input. SEG5 — AN LCD Analog output. RA6 TTL CLKOUT — SEG1 — CMOS General purpose I/O. CMOS FOSC/4 output. AN LCD Analog output. RA7 TTL CLKIN CMOS CMOS General purpose I/O. — External clock input (EC mode). SEG2 — AN LCD Analog output. RB0 TTL AN12 AN CMOS General purpose I/O. — INT ST — External interrupt. SEG0 — AN LCD Analog output. A/D Channel 12 input. RB1 TTL AN10 AN CMOS General purpose I/O. — SEG24 — AN LCD Analog output. VLCD1 AN — LCD analog input. RB2 TTL AN8 AN — A/D Channel 8 input. SEG25 — AN LCD Analog output. VLCD2 AN — LCD analog input. RB3 TTL AN9 AN — SEG26 — AN LCD Analog output. VLCD3 AN — LCD analog input. A/D Channel 10 input. CMOS General purpose I/O. CMOS General purpose I/O. A/D Channel 9 input. Legend: AN = Analog input or output CMOS = CMOS compatible input or output OD TTL = TTL compatible input ST = Schmitt Trigger input with CMOS levels I2C HV = High Voltage XTAL = Crystal Note 1: These pins have interrupt-on-change functionality. DS40001455F-page 8 = Open-Drain = Schmitt Trigger input with I2C levels  2011-2016 Microchip Technology Inc. PIC16LF1902/3 TABLE 1-2: PIC16LF1902/3 PINOUT DESCRIPTION (CONTINUED) Name RB4(1)/AN11/COM0 RB5(1)/AN13/COM1 RB6(1)/ICSPCLK/SEG14 RB7 (1) /ICSPDAT/SEG13 RC0/T1OSO/T1CKI RC1/T1OSI RC2/SEG3 RC3/SEG6 RC4/T1G/SEG11 RC5/SEG10 RC6/SEG9 RC7/SEG8 RE3/MCLR/VPP Function Input Type Output Type Description RB4 TTL AN11 AN CMOS General purpose I/O. — A/D Channel 11 input. COM0 — AN LCD Analog output. RB5 TTL AN13 AN CMOS General purpose I/O. — A/D Channel 13 input. AN LCD Analog output. COM1 — RB6 TTL ICSPCLK ST — Serial Programming Clock. SEG14 — AN LCD Analog output. CMOS General purpose I/O. RB7 TTL CMOS General purpose I/O. ICSPDAT ST CMOS ICSP™ Data I/O. SEG13 — AN RC0 TTL T1OSO XTAL XTAL T1CKI ST — RC1 TTL T1OSI XTAL RC2 TTL SEG3 — RC3 TTL SEG6 — RC4 TTL T1G XTAL SEG11 — RC5 TTL SEG10 — RC6 ST SEG9 — RC7 ST SEG8 — RE3 TTL LCD Analog output. CMOS General purpose I/O. Timer1 oscillator connection. Timer1 clock input. CMOS General purpose I/O. XTAL Timer1 oscillator connection. CMOS General purpose I/O. AN LCD Analog output. CMOS General purpose I/O. AN LCD Analog output. CMOS General purpose I/O. XTAL AN Timer1 oscillator connection. LCD Analog output. CMOS General purpose I/O. AN LCD Analog output. CMOS General purpose I/O. AN LCD Analog output. CMOS General purpose I/O. AN LCD Analog output. CMOS General purpose I/O. MCLR ST — Master Clear with internal pull-up. VPP HV — Programming voltage. VDD VDD Power — Positive supply. VSS VSS Power — Ground reference. Legend: AN = Analog input or output CMOS = CMOS compatible input or output OD TTL = TTL compatible input ST = Schmitt Trigger input with CMOS levels I2C HV = High Voltage XTAL = Crystal Note 1: These pins have interrupt-on-change functionality.  2011-2016 Microchip Technology Inc. = Open-Drain = Schmitt Trigger input with I2C levels DS40001455F-page 9 PIC16LF1902/3 2.0 ENHANCED MID-RANGE CPU This family of devices contains an enhanced mid-range 8-bit CPU core. The CPU has 49 instructions. Interrupt capability includes automatic context saving. The hardware stack is 16 levels deep and has Overflow and Underflow Reset capability. Direct, Indirect, and Relative Addressing modes are available. Two File Select Registers (FSRs) provide the ability to read program and data memory. • • • • Automatic Interrupt Context Saving 16-level Stack with Overflow and Underflow File Select Registers Instruction Set 2.1 Automatic Interrupt Context Saving During interrupts, certain registers are automatically saved in shadow registers and restored when returning from the interrupt. This saves stack space and user code. See Section 7.5 “Automatic Context Saving”, for more information. 2.2 16-level Stack with Overflow and Underflow These devices have an external stack memory 15 bits wide and 16 words deep. A Stack Overflow or Underflow will set the appropriate bit (STKOVF or STKUNF) in the PCON register, and if enabled will cause a software Reset. See Section 3.4 “Stack” for more details. 2.3 File Select Registers There are two 16-bit File Select Registers (FSR). FSRs can access all file registers and program memory, which allows one Data Pointer for all memory. When an FSR points to program memory, there is one additional instruction cycle in instructions using INDF to allow the data to be fetched. General purpose memory can now also be addressed linearly, providing the ability to access contiguous data larger than 80 bytes. There are also new instructions to support the FSRs. See Section 3.5 “Indirect Addressing” for more details. 2.4 Instruction Set There are 49 instructions for the enhanced mid-range CPU to support the features of the CPU. See Section 20.0 “Instruction Set Summary” for more details. DS40001455F-page 10  2011-2016 Microchip Technology Inc. PIC16LF1902/3 FIGURE 2-1: CORE BLOCK DIAGRAM 15 Configuration 15 MUX Flash Program Memory Program Bus 16-Level 8 Level Stack Stack (13-bit) (15-bit) 14 Instruction Instruction Reg reg 8 Data Bus Program Counter RAM Program Memory Read (PMR) 12 RAM Addr Addr MUX Indirect Addr 12 12 Direct Addr 7 5 BSR FSR Reg reg 15 FSR0reg Reg FSR FSR1 Reg FSR reg 15 STATUS Reg reg STATUS 8 3 Power-up Timer CLKIN CLKOUT Instruction Decodeand & Decode Control Timing Generation Oscillator Start-up Timer Power-on Reset Watchdog Timer Brown-out Reset MUX ALU 8 W Reg Internal Oscillator Block VDD  2011-2016 Microchip Technology Inc. VSS DS40001455F-page 11 PIC16LF1902/3 3.0 MEMORY ORGANIZATION 3.1 These devices contain the following types of memory: • Program Memory - Configuration Words - Device ID - User ID - Flash Program Memory • Data Memory - Core Registers - Special Function Registers - General Purpose RAM - Common RAM Program Memory Organization The enhanced mid-range core has a 15-bit program counter capable of addressing 32K x 14 program memory space. Table 3-1 shows the memory sizes implemented for the PIC16LF1902/3 family. Accessing a location above these boundaries will cause a wrap-around within the implemented memory space. The Reset vector is at 0000h and the interrupt vector is at 0004h (see Figures 3-1, and 3-2). The following features are associated with access and control of program memory and data memory: • PCL and PCLATH • Stack • Indirect Addressing TABLE 3-1: Device DEVICE SIZES AND ADDRESSES Program Memory Space (Words) Last Program Memory Address High-Endurance Flash Memory Address Range(1) PIC16LF1902 2,048 07FFh 0780h-07FFh PIC16LF1903 4,096 0FFFh 0F80h-0FFFh Note 1: High-endurance Flash applies to low byte of each address in the range. DS40001455F-page 12  2011-2016 Microchip Technology Inc. PIC16LF1902/3 FIGURE 3-1: PROGRAM MEMORY MAP AND STACK FOR PIC16LF1902 FIGURE 3-2: PC CALL, CALLW RETURN, RETLW Interrupt, RETFIE On-chip Program Memory PROGRAM MEMORY MAP AND STACK FOR PIC16LF1903 PC CALL, CALLW RETURN, RETLW Interrupt, RETFIE 15 15 Stack Level 0 Stack Level 1 Stack Level 0 Stack Level 1 Stack Level 15 Stack Level 15 Reset Vector 0000h Reset Vector 0000h Interrupt Vector 0004h 0005h Interrupt Vector 0004h 0005h Page 0 Rollover to Page 0 Wraps to Page 0 07FFh 0800h On-chip Program Memory Page 0 07FFh 0800h Page 1 Rollover to Page 0 Wraps to Page 0 0FFFh 1000h Wraps to Page 0 Rollover to Page 0  2011-2016 Microchip Technology Inc. 7FFFh Rollover to Page 1 7FFFh DS40001455F-page 13 PIC16LF1902/3 3.1.1 READING PROGRAM MEMORY AS DATA There are two methods of accessing constants in program memory. The first method is to use tables of RETLW instructions. The second method is to set an FSR to point to the program memory. 3.1.1.1 RETLW Instruction The RETLW instruction can be used to provide access to tables of constants. The recommended way to create such a table is shown in Example 3-1. EXAMPLE 3-1: constants BRW RETLW RETLW RETLW RETLW DATA0 DATA1 DATA2 DATA3 RETLW INSTRUCTION EXAMPLE 3-2: ACCESSING PROGRAM MEMORY VIA FSR constants RETLW DATA0 ;Index0 data RETLW DATA1 ;Index1 data RETLW DATA2 RETLW DATA3 my_function ;… LOTS OF CODE… MOVLW LOW constants MOVWF FSR1L MOVLW HIGH constants MOVWF FSR1H MOVIW 0[FSR1] ;THE PROGRAM MEMORY IS IN W ;Add Index in W to ;program counter to ;select data ;Index0 data ;Index1 data my_function ;… LOTS OF CODE… MOVLW DATA_INDEX call constants ;… THE CONSTANT IS IN W The BRW instruction makes this type of table very simple to implement. If your code must remain portable with previous generations of microcontrollers, then the BRW instruction is not available so the older table read method must be used. 3.1.1.2 Indirect Read with FSR The program memory can be accessed as data by setting bit 7 of the FSRxH register and reading the matching INDFx register. The MOVIW instruction will place the lower eight bits of the addressed word in the W register. Writes to the program memory cannot be performed via the INDF registers. Instructions that access the program memory via the FSR require one extra instruction cycle to complete. Example 3-2 demonstrates accessing the program memory via an FSR. The High directive will set bit if a label points to a location in program memory. DS40001455F-page 14  2011-2016 Microchip Technology Inc. PIC16LF1902/3 3.2 Data Memory Organization The data memory is partitioned in 32 memory banks with 128 bytes in a bank. Each bank consists of (Figure 3-3): • • • • 12 core registers 20 Special Function Registers (SFR) Up to 80 bytes of General Purpose RAM (GPR) 16 bytes of common RAM The active bank is selected by writing the bank number into the Bank Select Register (BSR). Unimplemented memory will read as ‘0’. All data memory can be accessed either directly (via instructions that use the file registers) or indirectly via the two File Select Registers (FSR). See Section 3.5 “Indirect Addressing” for more information. Data Memory uses a 12-bit address. The upper seven bits of the address define the Bank address and the lower five bits select the registers/RAM in that bank.  2011-2016 Microchip Technology Inc. 3.2.1 CORE REGISTERS The core registers contain the registers that directly affect the basic operation. The core registers occupy the first 12 addresses of every data memory bank (addresses x00h/x08h through x0Bh/x8Bh). These registers are listed below in Table 3-2. For for detailed information, see Table 3-4. TABLE 3-2: CORE REGISTERS Addresses BANKx x00h or x80h x01h or x81h x02h or x82h x03h or x83h x04h or x84h x05h or x85h x06h or x86h x07h or x87h x08h or x88h x09h or x89h x0Ah or x8Ah x0Bh or x8Bh INDF0 INDF1 PCL STATUS FSR0L FSR0H FSR1L FSR1H BSR WREG PCLATH INTCON DS40001455F-page 15 PIC16LF1902/3 3.2.1.1 STATUS Register The STATUS register, shown in Register 3-1, contains: • the arithmetic status of the ALU • the Reset status The STATUS register can be the destination for any instruction, like any other register. If the STATUS register is the destination for an instruction that affects the Z, DC or C bits, then the write to these three bits is disabled. These bits are set or cleared according to the device logic. Furthermore, the TO and PD bits are not writable. Therefore, the result of an instruction with the STATUS register as destination may be different than intended. REGISTER 3-1: U-0 It is recommended, therefore, that only BCF, BSF, SWAPF and MOVWF instructions are used to alter the STATUS register, because these instructions do not affect any Status bits. For other instructions not affecting any Status bits (Refer to Section 20.0 “Instruction Set Summary”). Note: The C and DC bits operate as Borrow and Digit Borrow out bits, respectively, in subtraction. STATUS: STATUS REGISTER U-0 — For example, CLRF STATUS will clear the upper three bits and set the Z bit. This leaves the STATUS register as ‘000u u1uu’ (where u = unchanged). — U-0 R-1/q R-1/q R/W-0/u R/W-0/u R/W-0/u — TO PD Z DC(1) C(1) bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared q = Value depends on condition bit 7-5 Unimplemented: Read as ‘0’ bit 4 TO: Time-out bit 1 = After power-up, CLRWDT instruction or SLEEP instruction 0 = A WDT time-out occurred bit 3 PD: Power-down bit 1 = After power-up or by the CLRWDT instruction 0 = By execution of the SLEEP instruction bit 2 Z: Zero bit 1 = The result of an arithmetic or logic operation is zero 0 = The result of an arithmetic or logic operation is not zero bit 1 DC: Digit Carry/Digit Borrow bit (ADDWF, ADDLW,SUBLW,SUBWF instructions)(1) 1 = A carry-out from the 4th low-order bit of the result occurred 0 = No carry-out from the 4th low-order bit of the result bit 0 C: Carry/Borrow bit(1) (ADDWF, ADDLW, SUBLW, SUBWF instructions)(1) 1 = A carry-out from the Most Significant bit of the result occurred 0 = No carry-out from the Most Significant bit of the result occurred Note 1: For Borrow, the polarity is reversed. A subtraction is executed by adding the two’s complement of the second operand. For rotate (RRF, RLF) instructions, this bit is loaded with either the high-order or low-order bit of the source register. DS40001455F-page 16  2011-2016 Microchip Technology Inc. PIC16LF1902/3 3.2.2 SPECIAL FUNCTION REGISTER The Special Function Registers (SFRs) are registers used by the application to control the desired operation of peripheral functions in the device. The Special Function Registers occupy the 20 bytes after the core registers of every data memory bank (addresses x0Ch/x8Ch through x1Fh/x9Fh). The registers associated with the operation of the peripherals are described in the appropriate peripheral chapter of this data sheet. 3.2.3 FIGURE 3-3: 7-bit Bank Offset 0Bh 0Ch GENERAL PURPOSE RAM Core Registers (12 bytes) Special Function Registers (20 bytes maximum) 1Fh 20h Linear Access to GPR The general purpose RAM can be accessed in a non-banked method via the FSRs. This can simplify access to large memory structures. See Section 3.5.2 “Linear Data Memory” for more information. 3.2.4 Memory Region 00h There are up to 80 bytes of GPR in each data memory bank. The Special Function Registers occupy the 20 bytes after the core registers of every data memory bank (addresses x0Ch/x8Ch through x1Fh/x9Fh). 3.2.3.1 BANKED MEMORY PARTITIONING General Purpose RAM (80 bytes maximum) COMMON RAM There are 16 bytes of common RAM accessible from all banks. 6Fh 70h Common RAM (16 bytes) 7Fh 3.2.5 DEVICE MEMORY MAPS The memory maps for PIC16LF1902 PIC16LF1903 are as shown in Table 3-3.  2011-2016 Microchip Technology Inc. and DS40001455F-page 17  2011-2016 Microchip Technology Inc. TABLE 3-3: PIC16LF1902/3 MEMORY MAP BANK 0 000h BANK 1 080h Core Registers (Table 3-2) 00Bh 00Ch 00Dh 00Eh 00Fh 010h 011h 012h 013h 014h 015h 016h 017h 018h 019h 01Ah 01Bh 01Ch 01Dh 01Eh 01Fh 020h — General Purpose Register 96 Bytes Core Registers (Table 3-2) 08Bh 08Ch 08Dh 08Eh 08Fh 090h 091h 092h 093h 094h 095h 096h 097h 098h 099h 09Ah 09Bh 09Ch 09Dh 09Eh TRISA TRISB TRISC — — PIE1 PIE2 — — OPTION_REG PCON WDTCON — OSCCON OSCSTAT ADRESL ADRESH ADCON0 ADCON1 Core Registers (Table 3-2) 10Bh 10Ch 10Dh 10Eh 10Fh 110h 111h 112h 113h 114h 115h 116h 117h 118h 119h 11Ah 11Bh 11Ch 11Dh 11Eh 09Fh — 11Fh 0A0h General Purpose 120h Register 32 Bytes 13Fh General Purpose 140h 0EFh 0F0h Register 48 Bytes(1) Legend: DS40001455F-page 18 Note 1: 0FFh LATA LATB LATC — — — — — — — BORCON FVRCON — — — — — — — — 19Fh 1A0h ANSELA ANSELB — — — PMADRL PMADRH PMDATL PMDATH PMCON1 PMCON2 — — — — — — — — — 20Bh 20Ch 20Dh 20Eh 20Fh 210h 211h 212h 213h 214h 215h 216h 217h 218h 219h 21Ah 21Bh 21Ch 21Dh 21Eh 21Fh 220h — WPUB — — WPUE — — — — — — — — — — — — — — — 26Fh 270h 28Bh 28Ch 28Dh 28Eh 28Fh 290h 291h 292h 293h 294h 295h 296h 297h 298h 299h 29Ah 29Bh 29Ch 29Dh 29Eh 29Fh 2A0h — — — — — — — — — — — — — — — — — — — — 30Bh 30Ch 30Dh 30Eh 30Fh 310h 311h 312h 313h 314h 315h 316h 317h 318h 319h 31Ah 31Bh 31Ch 31Dh 31Eh 31Fh 320h — Core Registers (Table 3-2) 38Bh 38Ch 38Dh 38Eh 38Fh 390h 391h 392h 393h 394h 395h 396h 397h 398h 399h 39Ah 39Bh 39Ch 39Dh 39Eh 39Fh 3A0h Unimplemented Read as ‘0’ Accesses 70h – 7Fh 2FFh — — — — — — — — — — — — — — — — — — — 36Fh 370h 2EFh 2F0h BANK 7 380h Core Registers (Table 3-2) Unimplemented Read as ‘0’ Accesses 70h – 7Fh 27Fh BANK 6 300h Core Registers (Table 3-2) Unimplemented Read as ‘0’ Accesses 70h – 7Fh 1FFh BANK 5 280h Core Registers (Table 3-2) Unimplemented Read as ‘0’ Accesses 70h – 7Fh = Unimplemented data memory locations, read as ‘0’. PIC16LF1903 only. 18Bh 18Ch 18Dh 18Eh 18Fh 190h 191h 192h 193h 194h 195h 196h 197h 198h 199h 19Ah 19Bh 19Ch 19Dh 19Eh 1EFh 1F0h 17Fh BANK 4 200h Core Registers (Table 3-2) General Purpose Register 80 Bytes(1) 16Fh 170h Accesses 70h – 7Fh 07Fh BANK 3 180h — Unimplemented Read as ‘0’ 3EFh 3F0h Accesses 70h – 7Fh 37Fh — — — — — — — — IOCBP IOCBN IOCBF — — — — — — — — Accesses 70h – 7Fh 3FFh PIC16LF1902/3 06Fh 070h PORTA PORTB PORTC — PORTE PIR1 PIR2 — — TMR0 TMR1L TMR1H T1CON T1GCON — — — — — BANK 2 100h PIC16LF1902/3 MEMORY MAP (CONTINUED) BANK 8 400h BANK 9 480h Core Registers (Table 3-2) 40Bh 40Ch Unimplemented Read as ‘0’ 46Fh 470h Common RAM (Accesses 70h – 7Fh) 47Fh Core Registers (Table 3-2) 48Bh 48Ch 4EFh 4F0h 4FFh BANK 16 800h 80Bh 80Ch Core Registers (Table 3-2)Table 3-2 87Fh Common RAM (Accesses 70h – 7Fh) 8EFh 8F0h 8FFh  2011-2016 Microchip Technology Inc. Legend: Common RAM (Accesses 70h – 7Fh) 97Fh 9EFh 9F0h 9FFh D7Fh Common RAM (Accesses 70h – 7Fh) Common RAM (Accesses 70h – 7Fh) = Unimplemented data memory locations, read as ‘0’ A7Fh DFFh Common RAM (Accesses 70h – 7Fh) 77Fh AEFh AF0h AFFh Unimplemented Read as ‘0’ B6Fh B70h B7Fh BANK 30 Core Registers (Table 3-2) Core Registers (Table 3-2) F0Bh F0Ch Unimplemented Read as ‘0’ EFFh Common RAM (Accesses 70h – 7Fh) F00h E8Bh E8Ch Common RAM (Accesses 70h – 7Fh) Core Registers (Table 3-2) B8Bh B8Ch B0Bh B0Ch Common RAM (Accesses 70h – 7Fh) BANK 23 B80h Core Registers (Table 3-2) BANK 29 EEFh EF0h Common RAM (Accesses 70h – 7Fh) BANK 22 Unimplemented Read as ‘0’ Unimplemented Read as ‘0’ E7Fh 76Fh 770h Unimplemented Read as ‘0’ B00h E80h Common RAM (Accesses 70h – 7Fh) 70Bh 70Ch Core Registers (Table 3-2) Core Registers (Table 3-2) E6Fh E70h Core Registers (Table 3-2) BANK 21 BANK 28 Unimplemented Read as ‘0’ Common RAM (Accesses 70h – 7Fh) A8Bh A8Ch E0Bh E0Ch Common RAM (Accesses 70h – 7Fh) 6FFh Unimplemented Read as ‘0’ A80h E00h Core Registers (Table 3-2) DEFh DF0h 6EFh 6F0h Unimplemented Read as ‘0’ BANK 27 D8Bh D8Ch 68Bh 68Ch Core Registers (Table 3-2) A6Fh A70h BANK 14 700h Core Registers (Table 3-2) BANK 20 Unimplemented Read as ‘0’ Unimplemented Read as ‘0’ D6Fh D70h 67Fh Common RAM (Accesses 70h – 7Fh) A0Bh A0Ch D80h D0Bh D0Ch 66Fh 670h Unimplemented Read as ‘0’ A00h 98Bh 98Ch Common RAM (Accesses 70h – 7Fh) 60Bh 60Ch Core Registers (Table 3-2) Core Registers (Table 3-2) Unimplemented Read as ‘0’ Common RAM (Accesses 70h – 7Fh) BANK 13 680h Core Registers (Table 3-2) BANK 19 BANK 26 Core Registers (Table 3-2) CFFh 5FFh Unimplemented Read as ‘0’ 980h D00h Common RAM (Accesses 70h – 7Fh) 5EFh 5F0h Unimplemented Read as ‘0’ BANK 25 CEFh CF0h 58Bh 58Ch Core Registers (Table 3-2) 96Fh 970h BANK 12 600h Core Registers (Table 3-2) BANK 18 Unimplemented Read as ‘0’ Unimplemented Read as ‘0’ C7Fh 57Fh Common RAM (Accesses 70h – 7Fh) 90Bh 90Ch 88Bh 88Ch C8Bh C8Ch Common RAM (Accesses 70h – 7Fh) 56Fh 570h Unimplemented Read as ‘0’ 900h C80h C0Bh C0Ch 50Bh 50Ch Core Registers (Table 3-2) Core Registers (Table 3-2) C6Fh C70h Common RAM (Accesses 70h – 7Fh) BANK 11 580h Core Registers (Table 3-2) BANK 17 BANK 24 C00h Unimplemented Read as ‘0’ 880h Unimplemented Read as ‘0’ 86Fh 870h BANK 10 500h Unimplemented Read as ‘0’ F6Fh F70h F7Fh Common RAM (Accesses 70h – 7Fh) Unimplemented Read as ‘0’ BEFh BF0h BFFh Common RAM (Accesses 70h – 7Fh) PIC16LF1902/3 DS40001455F-page 19 TABLE 3-3: PIC16LF1902/3 TABLE 3-3: PIC16LF1902/3 MEMORY MAP (CONTINUED) Bank 15 780h Core Registers (Table 3-2) 78Bh 78Ch Unimplemented Read as ‘0’ 790h 791h 792h 793h 794h 795h 796h 797h 798h 799h 79Ah 79Bh 79Ch 79Fh 7A0h 7A1h 7A2h 7A3h 7A4h 7A5h 7A6h 7A7h 7A8h 7A9h 7AAh 7ABh 7ACh 7ADh 7AEh 7AFh 7B0h 7B1h 7B2h 7B3h 7B4h 7B5h 7B6h 7B7h 7B8h LCDCON LCDPS LCDREF LCDCST LCDRL — — LCDSE0 LCDSE1 — LCDSE3 Unimplemented Read as ‘0’ LCDDATA0 LCDDATA1 — LCDDATA3 LCDDATA4 — LCDDATA6 LCDDATA7 — LCDDATA9 LCDDATA10 — LCDDATA12 — — LCDDATA15 — — LCDDATA18 — — LCDDATA21 — — Bank 31 F80h Core Registers (Table 3-2) F8Bh F8Ch FE3h FE4h FE5h FE6h FE7h FE8h FE9h FEAh FEBh FECh FEDh FEEh FEFh FF0h FFFh Unimplemented Read as ‘0’ STATUS_SHAD WREG_SHAD BSR_SHAD PCLATH_SHAD FSR0L_SHAD FSR0H_SHAD FSR1L_SHAD FSR1H_SHAD — STKPTR TOSL TOSH Common RAM (Accesses 70h – 7Fh) Unimplemented Read as ‘0’ 7EFh Legend: = Unimplemented data memory locations, read as ‘0’, DS40001455F-page 20  2011-2016 Microchip Technology Inc. PIC16LF1902/3 3.2.6 CORE FUNCTION REGISTERS SUMMARY The Core Function registers listed in Table 3-4 can be addressed from any Bank. TABLE 3-4: Addr Name CORE FUNCTION REGISTERS SUMMARY Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on POR, BOR Value on all other Resets Bank 0-31 x00h or INDF0 x80h Addressing this location uses contents of FSR0H/FSR0L to address data memory (not a physical register) xxxx xxxx uuuu uuuu x01h or INDF1 x81h Addressing this location uses contents of FSR1H/FSR1L to address data memory (not a physical register) xxxx xxxx uuuu uuuu x02h or PCL x82h Program Counter (PC) Least Significant Byte 0000 0000 0000 0000 ---1 1000 ---q quuu x03h or STATUS x83h — — — TO PD Z DC C x04h or FSR0L x84h Indirect Data Memory Address 0 Low Pointer 0000 0000 uuuu uuuu x05h or FSR0H x85h Indirect Data Memory Address 0 High Pointer 0000 0000 0000 0000 x06h or FSR1L x86h Indirect Data Memory Address 1 Low Pointer 0000 0000 uuuu uuuu x07h or FSR1H x87h Indirect Data Memory Address 1 High Pointer 0000 0000 0000 0000 ---0 0000 ---0 0000 0000 0000 uuuu uuuu -000 0000 -000 0000 0000 0000 0000 0000 x08h or BSR x88h — x09h or WREG x89h — BSR4 BSR3 BSR2 BSR1 BSR0 Working Register x0Ah or PCLATH x8Ah — x0Bh or INTCON x8Bh GIE Legend: — Write Buffer for the upper 7 bits of the Program Counter PEIE TMR0IE INTE IOCIE TMR0IF INTF IOCIF x = unknown, u = unchanged, q = value depends on condition, - = unimplemented, read as ‘0’, r = reserved. Shaded locations are unimplemented, read as ‘0’.  2011-2016 Microchip Technology Inc. DS40001455F-page 21 PIC16LF1902/3 TABLE 3-5: Addr SPECIAL FUNCTION REGISTER SUMMARY Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on POR, BOR Value on all other Resets Bank 0 00Ch PORTA PORTA Data Latch when written: PORTA pins when read xxxx xxxx uuuu uuuu 00Dh PORTB PORTB Data Latch when written: PORTB pins when read xxxx xxxx uuuu uuuu 00Eh PORTC PORTC Data Latch when written: PORTC pins when read xxxx xxxx uuuu uuuu 00Fh — Unimplemented 010h PORTE 011h PIR1 012h PIR2 — — — — — TMR1GIF ADIF — — — — — — — RE3 — — — ---- x--- ---- u--- — — TMR1IF 00-- ---0 0000 ---0 — LCDIF — — ---- -0-- ---- -0-- 013h — Unimplemented — — 014h — Unimplemented — — 015h TMR0 Timer0 Module Register xxxx xxxx uuuu uuuu 016h TMR1L Holding Register for the Least Significant Byte of the 16-bit TMR1 Register xxxx xxxx uuuu uuuu 017h TMR1H Holding Register for the Most Significant Byte of the 16-bit TMR1 Register 018h T1CON TMR1CS1 TMR1CS0 019h T1GCON TMR1GE 01Ah to — 01Fh T1GPOL xxxx xxxx uuuu uuuu T1CKPS1 T1CKPS0 T1OSCEN T1SYNC — T1GTM T1GSPM T1GGO/ DONE T1GVAL T1GSS1 TMR1ON 0000 00-0 uuuu uu-u T1GSS0 Unimplemented 0000 0x00 uuuu uxuu — — Bank 1 08Ch TRISA PORTA Data Direction Register 1111 1111 1111 1111 08Dh TRISB PORTB Data Direction Register 1111 1111 1111 1111 08Eh TRISC PORTC Data Direction Register 1111 1111 1111 1111 08Fh — Unimplemented — — — — — —(2) 091h PIE1 TMR1GIE ADIE — — 092h PIE2 — — — — 090h TRISE — — — — ---- 1--- ---- 1--- — — — TMR1IE 00-- ---0 0000 ---0 — LCDIE — — ---- -0-- ---- -0-- 093h — Unimplemented — — 094h — Unimplemented — — 095h OPTION_REG WPUEN INTEDG 096h PCON STKOVF STKUNF — RWDT RMCLR RI POR — — WDTPS4 WDTPS3 WDTPS2 WDTPS1 WDTPS0 — IRCF3 IRCF2 IRCF1 IRCF0 — SCS1 SCS0 -011 1-00 -011 1-00 T1OSCR — OSTS HFIOFR — — LFIOFR HFIOFS 0-q0 --00 q-qq --0q 097h WDTCON 098h — 09Ah OSCSTAT A/D Result Register Low 09Ch ADRESH A/D Result Register High 09Dh ADCON0 09Eh ADCON1 Note 1: 2: PSA PS2 PS1 PS0 1111 1111 1111 1111 BOR 00-1 11qq qq-q qquu SWDTEN --01 0110 --01 0110 — 09Bh ADRESL Legend: TMR0SE Unimplemented 099h OSCCON 09Fh — TMR0CS — xxxx xxxx uuuu uuuu xxxx xxxx uuuu uuuu — CHS4 CHS3 CHS2 CHS1 CHS0 ADFM ADCS2 ADCS1 ADCS0 — — GO/DONE ADON -000 0000 -000 0000 ADPREF1 ADPREF0 0000 ---- 0000 ---- Unimplemented — — x = unknown, u = unchanged, q = value depends on condition, - = unimplemented, read as ‘0’, r = reserved. Shaded locations are unimplemented, read as ‘0’. These registers can be addressed from any bank. Unimplemented, read as ‘1’. DS40001455F-page 22  2011-2016 Microchip Technology Inc. PIC16LF1902/3 TABLE 3-5: Addr Name SPECIAL FUNCTION REGISTER SUMMARY (CONTINUED) Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on POR, BOR Value on all other Resets Bank 2 10Ch LATA PORTA Data Latch xxxx xxxx uuuu uuuu 10Dh LATB PORTB Data Latch xxxx xxxx uuuu uuuu 10Eh LATC PORTC Data Latch xxxx xxxx uuuu uuuu 10Fh to — 115h Unimplemented — — 116h BORCON SBOREN BORFS — — — — — BORRDY 10-- ---q uu-- ---u 117h FVRCON FVREN FVRRDY TSEN TSRNG — — ADFVR1 ADFVR0 0q00 --00 0q00 --00 118h to — 11Fh Unimplemented — — Bank 3 18Ch ANSELA — — ANSA5 — ANSA3 ANSA2 ANSA1 ANSA0 --1- 1111 --11 1111 18Dh ANSELB — — ANSB5 ANSB4 ANSB3 ANSB2 ANSB1 ANSB0 --11 1111 --11 1111 18Eh — Unimplemented — — 18Fh — Unimplemented — — 190h — Unimplemented — — 191h PMADRL Program Memory Address Register Low Byte 192h PMADRH 193h PMDATL 194h PMDATH 195h PMCON1 —(2) 0000 0000 0000 0000 Program Memory Address Register High Byte 1000 0000 1000 0000 Program Memory Read Data Register Low Byte — — —(2) CFGS xxxx xxxx uuuu uuuu Program Memory Read Data Register High Byte LWLO 196h PMCON2 Program Memory Control Register 2 197h to — 19Fh Unimplemented FREE WRERR WREN --xx xxxx --uu uuuu WR RD 1000 x000 1000 q000 0000 0000 0000 0000 — — — — Bank 4 20Ch — Unimplemented 20Dh WPUB WPUB7 WPUB6 WPUB5 WPUB4 WPUB3 WPUB2 WPUB1 WPUB0 1111 1111 1111 1111 20Eh — Unimplemented — — 20Fh — Unimplemented — — 210h WPUE 211h to — 21Fh — — — — WPUE3 — — — ---- 1--- ---- 1--- Unimplemented — — Unimplemented — — Unimplemented — — Bank 5 28Ch — — 29Fh Bank 6 30Ch — — 31Fh Legend: Note 1: 2: x = unknown, u = unchanged, q = value depends on condition, - = unimplemented, read as ‘0’, r = reserved. Shaded locations are unimplemented, read as ‘0’. These registers can be addressed from any bank. Unimplemented, read as ‘1’.  2011-2016 Microchip Technology Inc. DS40001455F-page 23 PIC16LF1902/3 TABLE 3-5: Addr SPECIAL FUNCTION REGISTER SUMMARY (CONTINUED) Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on POR, BOR Value on all other Resets — — Bank 7 38Ch — — 393h Unimplemented 394h IOCBP IOCBP7 IOCBP6 IOCBP5 IOCBP4 IOCBP3 IOCBP2 IOCBP1 IOCBP0 0000 0000 0000 0000 395h IOCBN IOCBN7 IOCBN6 IOCBN5 IOCBN4 IOCBN3 IOCBN2 IOCBN1 IOCBN0 0000 0000 0000 0000 396h IOCBF IOCBF7 IOCBF6 IOCBF5 IOCBF4 IOCBF3 IOCBF2 IOCBF1 IOCBF0 0000 0000 0000 0000 397h — — 39Fh Unimplemented — — Unimplemented — — Unimplemented — — Bank 8-14 x0Ch or x8Ch to — x1Fh or x9Fh Bank 15 78Ch — — 790h LCDEN SLPEN WERR — CS1 CS0 LMUX1 LMUX0 000- 0011 000- 0011 WFT BIASMD LCDA WA LP3 LP2 LP1 LP0 0000 0000 0000 0000 793h LCDREF LCDIRE — LCDIRI — VLCD3PE VLCD2PE VLCD1PE — 0-0- 000- 0-0- 000- 794h LCDCST — — — — — LCDCST2 LCDCST1 LCDCST0 ---- -000 ---- -000 LRLAP1 LRLAP0 LRLBP1 LRLBP0 — LRLAT2 791h LCDCON 792h LCDPS 795h LCDRL LRLAT1 LRLAT0 0000 -000 0000 -000 796h — Unimplemented — — 797h — Unimplemented — — 798h LCDSE0 799h LCDSE1 79Ah — SE7 SE6 SE5 SE4 SE3 SE2 SE1 SE0 0000 0000 uuuu uuuu SE15 SE14 SE13 SE12 SE11 SE10 SE9 SE8 0000 0000 uuuu uuuu — — — SE26 SE25 SE24 ---- -000 ---- -uuu Unimplemented 79Bh LCDSE3 79Dh — — 79Fh — — — Unimplemented — — — 7A0h LCDDATA0 SEG7 COM0 SEG6 COM0 SEG5 COM0 SEG4 COM0 SEG3 COM0 SEG2 COM0 SEG1 COM0 SEG0 COM0 xxxx xxxx uuuu uuuu 7A1h LCDDATA1 SEG15 COM0 SEG14 COM0 SEG13 COM0 SEG12 COM0 SEG11 COM0 SEG10 COM0 SEG9 COM0 SEG8 COM0 xxxx xxxx uuuu uuuu 7A2h — Unimplemented — — 7A3h LCDDATA3 SEG7 COM1 SEG6 COM1 SEG5 COM1 SEG4 COM1 SEG3 COM1 SEG2 COM1 SEG1 COM1 SEG0 COM1 xxxx xxxx uuuu uuuu 7A4h LCDDATA4 SEG15 COM1 SEG14 COM1 SEG13 COM1 SEG12 COM1 SEG11 COM1 SEG10 COM1 SEG9 COM1 SEG8 COM1 xxxx xxxx uuuu uuuu 7A5h — Unimplemented — — 7A6h LCDDATA6 SEG7 COM2 SEG6 COM2 SEG5 COM2 SEG4 COM2 SEG3 COM2 SEG2 COM2 SEG1 COM2 SEG0 COM2 xxxx xxxx uuuu uuuu 7A7h LCDDATA7 SEG15 COM2 SEG14 COM2 SEG13 COM2 SEG12 COM2 SEG11 COM2 SEG10 COM2 SEG9 COM2 SEG8 COM2 xxxx xxxx uuuu uuuu 7A8h — Unimplemented — — 7A9h LCDDATA9 SEG7 COM3 SEG6 COM3 SEG5 COM3 SEG4 COM3 SEG3 COM3 SEG2 COM3 SEG1 COM3 SEG0 COM3 xxxx xxxx uuuu uuuu 7AAh LCDDATA10 SEG15 COM3 SEG14 COM3 SEG13 COM3 SEG12 COM3 SEG11 COM3 SEG10 COM3 SEG9 COM3 SEG8 COM3 xxxx xxxx uuuu uuuu Legend: Note 1: 2: x = unknown, u = unchanged, q = value depends on condition, - = unimplemented, read as ‘0’, r = reserved. Shaded locations are unimplemented, read as ‘0’. These registers can be addressed from any bank. Unimplemented, read as ‘1’. DS40001455F-page 24  2011-2016 Microchip Technology Inc. PIC16LF1902/3 TABLE 3-5: Addr SPECIAL FUNCTION REGISTER SUMMARY (CONTINUED) Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 — — — — SEG26 COM0 SEG25 COM0 SEG24 COM0 Value on POR, BOR Value on all other Resets — — Bank 15 (Continued) 7ABh — Unimplemented 7ACh LCDDATA12 — ---- -xxx ---- -uuu 7ADh — Unimplemented — — 7AEh — Unimplemented — — 7AFh LCDDATA15 — — — — — SEG26 COM1 SEG25 COM1 SEG24 COM1 ---- -xxx ---- -uuu 7B0h — Unimplemented — — 7B1h — Unimplemented — — 7B2h LCDDATA18 — — — — — SEG26 COM2 SEG25 COM2 SEG24 COM2 ---- -xxx ---- -uuu 7B3h — Unimplemented — — 7B4h — Unimplemented — — 7B5h LCDDATA21 7B6h — — 7EFh — — — — — SEG26 COM3 SEG25 COM3 SEG24 COM3 ---- -xxx ---- -uuu Unimplemented — — Unimplemented — — Unimplemented — — Bank 16-30 x0Ch or x8Ch to — x1Fh or x9Fh Bank 31 F8Ch — — FE3h FE4h STATUS_SHAD FE5h WREG_SHAD FE6h BSR_SHAD FE7h PCLATH_SHAD — — — — — Z_SHAD DC_SHAD C_SHAD ---- -xxx ---- -uuu Working Register Normal (Non-ICD) Shadow — — — — Bank Select Register Normal (Non-ICD) Shadow Program Counter Latch High Register Normal (Non-ICD) Shadow xxxx xxxx uuuu uuuu ---x xxxx ---u uuuu -xxx xxxx uuuu uuuu FE8h FSR0L_SHAD Indirect Data Memory Address 0 Low Pointer Normal (Non-ICD) Shadow xxxx xxxx uuuu uuuu FE9h FSR0H_SHAD Indirect Data Memory Address 0 High Pointer Normal (Non-ICD) Shadow xxxx xxxx uuuu uuuu FEAh FSR1L_SHAD Indirect Data Memory Address 1 Low Pointer Normal (Non-ICD) Shadow xxxx xxxx uuuu uuuu FEBh FSR1H_SHAD Indirect Data Memory Address 1 High Pointer Normal (Non-ICD) Shadow xxxx xxxx uuuu uuuu FECh — Unimplemented FEDh STKPTR FEEh TOSL FEFh TOSH Legend: Note 1: 2: — — — — Current Stack Pointer Top of Stack Low byte — Top of Stack High byte — ---1 1111 ---1 1111 xxxx xxxx uuuu uuuu -xxx xxxx -uuu uuuu x = unknown, u = unchanged, q = value depends on condition, - = unimplemented, read as ‘0’, r = reserved. Shaded locations are unimplemented, read as ‘0’. These registers can be addressed from any bank. Unimplemented, read as ‘1’.  2011-2016 Microchip Technology Inc. DS40001455F-page 25 PIC16LF1902/3 3.3 3.3.3 PCL and PCLATH COMPUTED FUNCTION CALLS The Program Counter (PC) is 15 bits wide. The low byte comes from the PCL register, which is a readable and writable register. The high byte (PC) is not directly readable or writable and comes from PCLATH. On any Reset, the PC is cleared. Figure 3-4 shows the five situations for the loading of the PC. A computed function CALL allows programs to maintain tables of functions and provide another way to execute state machines or look-up tables. When performing a table read using a computed function CALL, care should be exercised if the table location crosses a PCL memory boundary (each 256-byte block). FIGURE 3-4: If using the CALL instruction, the PCH and PCL registers are loaded with the operand of the CALL instruction. PCH is loaded with PCLATH. PC LOADING OF PC IN DIFFERENT SITUATIONS 14 PCH 6 7 14 PCH PCL 0 PCLATH PC 8 ALU Result PCL 0 4 0 11 OPCODE PC 14 PCH PCL 0 CALLW 6 PCLATH PC Instruction with PCL as Destination GOTO, CALL 6 PCLATH 0 14 7 0 PCH 8 W PCL 0 BRW 14 PCH 3.3.4 BRANCHING The branching instructions add an offset to the PC. This allows relocatable code and code that crosses page boundaries. There are two forms of branching, BRW and BRA. The PC will have incremented to fetch the next instruction in both cases. When using either branching instruction, a PCL memory boundary may be crossed. If using BRW, load the W register with the desired unsigned address and execute BRW. The entire PC will be loaded with the address PC + 1 + W. If using BRA, the entire PC will be loaded with PC + 1 +, the signed value of the operand of the BRA instruction. 15 PC + W PC The CALLW instruction enables computed calls by combining PCLATH and W to form the destination address. A computed CALLW is accomplished by loading the W register with the desired address and executing CALLW. The PCL register is loaded with the value of W and PCH is loaded with PCLATH. PCL 0 BRA 15 PC + OPCODE 3.3.1 MODIFYING PCL Executing any instruction with the PCL register as the destination simultaneously causes the Program Counter PC bits (PCH) to be replaced by the contents of the PCLATH register. This allows the entire contents of the program counter to be changed by writing the desired upper seven bits to the PCLATH register. When the lower eight bits are written to the PCL register, all 15 bits of the program counter will change to the values contained in the PCLATH register and those being written to the PCL register. 3.3.2 COMPUTED GOTO A computed GOTO is accomplished by adding an offset to the program counter (ADDWF PCL). When performing a table read using a computed GOTO method, care should be exercised if the table location crosses a PCL memory boundary (each 256-byte block). Refer to the Application Note AN556, “Implementing a Table Read” (DS00556). DS40001455F-page 26  2011-2016 Microchip Technology Inc. PIC16LF1902/3 3.4 3.4.1 Stack The stack is available through the TOSH, TOSL and STKPTR registers. STKPTR is the current value of the Stack Pointer. TOSH:TOSL register pair points to the TOP of the stack. Both registers are read/writable. TOS is split into TOSH and TOSL due to the 15-bit size of the PC. To access the stack, adjust the value of STKPTR, which will position TOSH:TOSL, then read/write to TOSH:TOSL. STKPTR is five bits to allow detection of overflow and underflow. All devices have a 16-level x 15-bit wide hardware stack (refer to Figures 3-3 and 3-3). The stack space is not part of either program or data space. The PC is PUSHed onto the stack when CALL or CALLW instructions are executed or an interrupt causes a branch. The stack is POPed in the event of a RETURN, RETLW or a RETFIE instruction execution. PCLATH is not affected by a PUSH or POP operation. The stack operates as a circular buffer if the STVREN bit is programmed to ‘0‘ (Configuration Word 2). This means that after the stack has been PUSHed sixteen times, the seventeenth PUSH overwrites the value that was stored from the first PUSH. The eighteenth PUSH overwrites the second PUSH (and so on). The STKOVF and STKUNF flag bits will be set on an Overflow/Underflow, regardless of whether the Reset is enabled. Note: Note: Care should be taken when modifying the STKPTR while interrupts are enabled. During normal program operation, CALL, CALLW and Interrupts will increment STKPTR while RETLW, RETURN, and RETFIE will decrement STKPTR. At any time STKPTR can be inspected to see how much stack is left. The STKPTR always points at the currently used place on the stack. Therefore, a CALL or CALLW will increment the STKPTR and then write the PC, and a return will unload the PC and then decrement the STKPTR. There are no instructions/mnemonics called PUSH or POP. These are actions that occur from the execution of the CALL, CALLW, RETURN, RETLW and RETFIE instructions or the vectoring to an interrupt address. FIGURE 3-5: ACCESSING THE STACK Reference Figure 3-5 through Figure 3-8 for examples of accessing the stack. ACCESSING THE STACK EXAMPLE 1 TOSH:TOSL 0x0F STKPTR = 0x1F Stack Reset Disabled (STVREN = 0) 0x0E 0x0D 0x0C 0x0B 0x0A Initial Stack Configuration: 0x09 After Reset, the stack is empty. The empty stack is initialized so the Stack Pointer is pointing at 0x1F. If the Stack Overflow/Underflow Reset is enabled, the TOSH/TOSL registers will return ‘0’. If the Stack Overflow/Underflow Reset is disabled, the TOSH/TOSL registers will return the contents of stack address 0x0F. 0x08 0x07 0x06 0x05 0x04 0x03 0x02 0x01 0x00 TOSH:TOSL  2011-2016 Microchip Technology Inc. 0x1F 0x0000 STKPTR = 0x1F Stack Reset Enabled (STVREN = 1) DS40001455F-page 27 PIC16LF1902/3 FIGURE 3-6: ACCESSING THE STACK EXAMPLE 2 0x0F 0x0E 0x0D 0x0C 0x0B 0x0A 0x09 This figure shows the stack configuration after the first CALL or a single interrupt. If a RETURN instruction is executed, the return address will be placed in the Program Counter and the Stack Pointer decremented to the empty state (0x1F). 0x08 0x07 0x06 0x05 0x04 0x03 0x02 0x01 TOSH:TOSL FIGURE 3-7: 0x00 Return Address STKPTR = 0x00 ACCESSING THE STACK EXAMPLE 3 0x0F 0x0E 0x0D 0x0C After seven CALLs or six CALLs and an interrupt, the stack looks like the figure on the left. A series of RETURN instructions will repeatedly place the return addresses into the Program Counter and pop the stack. 0x0B 0x0A 0x09 0x08 0x07 TOSH:TOSL DS40001455F-page 28 0x06 Return Address 0x05 Return Address 0x04 Return Address 0x03 Return Address 0x02 Return Address 0x01 Return Address 0x00 Return Address STKPTR = 0x06  2011-2016 Microchip Technology Inc. PIC16LF1902/3 FIGURE 3-8: ACCESSING THE STACK EXAMPLE 4 TOSH:TOSL 3.4.2 0x0F Return Address 0x0E Return Address 0x0D Return Address 0x0C Return Address 0x0B Return Address 0x0A Return Address 0x09 Return Address 0x08 Return Address 0x07 Return Address 0x06 Return Address 0x05 Return Address 0x04 Return Address 0x03 Return Address 0x02 Return Address 0x01 Return Address 0x00 Return Address When the stack is full, the next CALL or an interrupt will set the Stack Pointer to 0x10. This is identical to address 0x00 so the stack will wrap and overwrite the return address at 0x00. If the Stack Overflow/Underflow Reset is enabled, a Reset will occur and location 0x00 will not be overwritten. STKPTR = 0x10 OVERFLOW/UNDERFLOW RESET If the STVREN bit in Configuration Word 2 is programmed to ‘1’, the device will be reset if the stack is PUSHed beyond the sixteenth level or POPed beyond the first level, setting the appropriate bits (STKOVF or STKUNF, respectively) in the PCON register. 3.5 Indirect Addressing The INDFn registers are not physical registers. Any instruction that accesses an INDFn register actually accesses the register at the address specified by the File Select Registers (FSR). If the FSRn address specifies one of the two INDFn registers, the read will return ‘0’ and the write will not occur (though Status bits may be affected). The FSRn register value is created by the pair FSRnH and FSRnL. The FSR registers form a 16-bit address that allows an addressing space with 65536 locations. These locations are divided into three memory regions: • Traditional Data Memory • Linear Data Memory • Program Flash Memory  2011-2016 Microchip Technology Inc. DS40001455F-page 29 PIC16LF1902/3 FIGURE 3-9: INDIRECT ADDRESSING 0x0000 0x0000 Traditional Data Memory 0x0FFF 0x1000 0x1FFF 0x0FFF Reserved 0x2000 Linear Data Memory 0x29AF 0x29B0 FSR Address Range 0x7FFF 0x8000 Reserved 0x0000 Program Flash Memory 0xFFFF Note: 0x7FFF Not all memory regions are completely implemented. Consult device memory tables for memory limits. DS40001455F-page 30  2011-2016 Microchip Technology Inc. PIC16LF1902/3 3.5.1 TRADITIONAL DATA MEMORY The traditional data memory is a region from FSR address 0x000 to FSR address 0xFFF. The addresses correspond to the absolute addresses of all SFR, GPR and common registers. FIGURE 3-10: TRADITIONAL DATA MEMORY MAP Direct Addressing 4 BSR 0 6 Indirect Addressing From Opcode 0 7 0 Bank Select Location Select FSRxH 0 0 0 7 FSRxL 0 0 Bank Select 00000 00001 00010 11111 Bank 0 Bank 1 Bank 2 Bank 31 Location Select 0x00 0x7F  2011-2016 Microchip Technology Inc. DS40001455F-page 31 PIC16LF1902/3 3.5.2 3.5.3 LINEAR DATA MEMORY The linear data memory is the region from FSR address 0x2000 to FSR address 0x29AF. This region is a virtual region that points back to the 80-byte blocks of GPR memory in all the banks. Unimplemented memory reads as 0x00. Use of the linear data memory region allows buffers to be larger than 80 bytes because incrementing the FSR beyond one bank will go directly to the GPR memory of the next bank. The 16 bytes of common memory are not included in the linear data memory region. FIGURE 3-11: LINEAR DATA MEMORY MAP To make constant data access easier, the entire program Flash memory is mapped to the upper half of the FSR address space. When the MSB of FSRnH is set, the lower 15 bits are the address in program memory which will be accessed through INDF. Only the lower eight bits of each memory location is accessible via INDF. Writing to the program Flash memory cannot be accomplished via the FSR/INDF interface. All instructions that access program Flash memory via the FSR/INDF interface will require one additional instruction cycle to complete. FIGURE 3-12: 7 7 FSRnH 0 7 FSRnL 0 PROGRAM FLASH MEMORY FSRnH PROGRAM FLASH MEMORY MAP 0 7 FSRnL 0 1 0 0 1 Location Select Location Select 0x2000 0x8000 0x0000 0x020 Bank 0 0x06F 0x0A0 Bank 1 0x0EF 0x120 Program Flash Memory (low 8 bits) Bank 2 0x16F 0xF20 Bank 30 0x29AF DS40001455F-page 32 0xF6F 0xFFFF 0x7FFF  2011-2016 Microchip Technology Inc. PIC16LF1902/3 4.0 DEVICE CONFIGURATION Device Configuration consists of Configuration Word 1 and Configuration Word 2, Code Protection and Device ID. 4.1 Configuration Words There are several Configuration Word bits that allow different oscillator and memory protection options. These are implemented as Configuration Word 1 at 8007h and Configuration Word 2 at 8008h. Note: The DEBUG bit in Configuration Words is managed automatically by device development tools including debuggers and programmers. For normal device operation, this bit should be maintained as a ‘1’.  2011-2016 Microchip Technology Inc. DS40001455F-page 33 PIC16LF1902/3 REGISTER 4-1: CONFIGURATION WORD 1 U-1 U-1 R/P-1 — — CLKOUTEN R/P-1 R/P-1 U-1 BOREN — bit 13 R/P-1 R/P-1 R/P-1 CP MCLRE PWRTE bit 8 R/P-1 R/P-1 WDTE U-1 R/P-1 — R/P-1 FOSC bit 7 bit 0 Legend: R = Readable bit P = Programmable bit U = Unimplemented bit, read as ‘1’ ‘0’ = Bit is cleared ‘1’ = Bit is set -n = Value when blank or after Bulk Erase bit 13-12 Unimplemented: Read as ‘1’ bit 11 CLKOUTEN: Clock Out Enable bit 1 = CLKOUT function is disabled. I/O function on the CLKOUT pin. 0 = CLKOUT function is enabled on the CLKOUT pin bit 10-9 BOREN: Brown-out Reset Enable bits 11 = BOR enabled 10 = BOR enabled during operation and disabled in Sleep 01 = BOR controlled by SBOREN bit of the BORCON register 00 = BOR disabled bit 8 Unimplemented: Read as ‘1’ bit 7 CP: Code Protection bit 1 = Program memory code protection is disabled 0 = Program memory code protection is enabled bit 6 MCLRE: MCLR/VPP Pin Function Select bit If LVP bit = 1: This bit is ignored. If LVP bit = 0: 1 = MCLR/VPP pin function is MCLR; Weak pull-up enabled. 0 = MCLR/VPP pin function is digital input; MCLR internally disabled; Weak pull-up under control of WPUE3 bit. bit 5 PWRTE: Power-up Timer Enable bit 1 = PWRT disabled 0 = PWRT enabled bit 4-3 WDTE: Watchdog Timer Enable bit 11 = WDT enabled 10 = WDT enabled while running and disabled in Sleep 01 = WDT controlled by the SWDTEN bit in the WDTCON register 00 = WDT disabled bit 2 Unimplemented: Read as ‘1’ bit 1-0 FOSC: Oscillator Selection bits 00 = INTOSC oscillator: I/O function on CLKIN pin 01 = ECL: External Clock, Low-Power mode (0-0.5 MHz): device clock supplied to CLKIN pin 10 = ECM: External Clock, Medium-Power mode (0.5-4 MHz): device clock supplied to CLKIN pin 11 = ECH: External Clock, High-Power mode (4-32 MHz): device clock supplied to CLKIN pin DS40001455F-page 34  2011-2016 Microchip Technology Inc. PIC16LF1902/3 REGISTER 4-2: CONFIGURATION WORD 2 R/P-1 (1) LVP R/P-1 DEBUG R/P-1 (2) LPBOR R/P-1 (3) BORV R/P-1 U-1 STVREN — bit 13 bit 8 U-1 U-1 U-1 U-1 U-1 U-1 — — — — — — R/P-1 R/P-1 WRT bit 7 bit 0 Legend: R = Readable bit P = Programmable bit U = Unimplemented bit, read as ‘1’ ‘0’ = Bit is cleared ‘1’ = Bit is set -n = Value when blank or after Bulk Erase bit 13 LVP: Low-Voltage Programming Enable bit(1) 1 = Low-voltage programming enabled 0 = High-voltage on MCLR must be used for programming bit 12 DEBUG: In-Circuit Debugger Mode bit(2) 1 = In-Circuit Debugger disabled, ICSPCLK and ICSPDAT are general purpose I/O pins 0 = In-Circuit Debugger enabled, ICSPCLK and ICSPDAT are dedicated to the debugger bit 11 LPBOR: Low-Power BOR bit 1 = Low-Power BOR is disabled 0 = Low-Power BOR is enabled bit 10 BORV: Brown-out Reset Voltage Selection bit(3) 1 = Brown-out Reset voltage (VBOR), low trip point selected 0 = Brown-out Reset voltage (VBOR) high trip point selected bit 9 STVREN: Stack Overflow/Underflow Reset Enable bit 1 = Stack Overflow or Underflow will cause a Reset 0 = Stack Overflow or Underflow will not cause a Reset bit 8-2 Unimplemented: Read as ‘1’ bit 1-0 WRT: Flash Memory Self-Write Protection bits 2 kW Flash memory (PIC16LF1902 only): 11 = Write protection off 10 = 000h to 1FFh write-protected, 200h to 7FFh may be modified by PMCON control 01 = 000h to 3FFh write-protected, 400h to 7FFh may be modified by PMCON control 00 = 000h to 7FFh write-protected, no addresses may be modified by PMCON control 4 kW Flash memory (PIC16LF1903 only): 11 = Write protection off 10 = 000h to 1FFh write-protected, 200h to FFFh may be modified by PMCON control 01 = 000h to 7FFh write-protected, 800h to FFFh may be modified by PMCON control 00 = 000h to FFFh write-protected, no addresses may be modified by PMCON control Note 1: 2: 3: The LVP bit cannot be programmed to ‘0’ when Programming mode is entered via LVP. The DEBUG bit in Configuration Words is managed automatically by device development tools including debuggers and programmers. For normal device operation, this bit should be maintained as a ‘1’. See VBOR parameter for specific trip point voltages.  2011-2016 Microchip Technology Inc. DS40001455F-page 35 PIC16LF1902/3 4.2 Code Protection Code protection allows the device to be protected from unauthorized access. Program memory protection is controlled independently. Internal access to the program memory is unaffected by any code protection setting. 4.2.1 PROGRAM MEMORY PROTECTION The entire program memory space is protected from external reads and writes by the CP bit in Configuration Word 1. When CP = 0, external reads and writes of program memory are inhibited and a read will return all ‘0’s. The CPU can continue to read program memory, regardless of the protection bit settings. Writing the program memory is dependent upon the write protection setting. See Section 4.3 “Write Protection” for more information. 4.3 Write Protection Write protection allows the device to be protected from unintended self-writes. Applications, such as boot loader software, can be protected while allowing other regions of the program memory to be modified. The WRT bits in Configuration Word 2 define the size of the program memory block that is protected. 4.4 User ID Four memory locations (8000h-8003h) are designated as ID locations where the user can store checksum or other code identification numbers. These locations are readable and writable during normal execution. See Section 10.4 “User ID, Device ID and Configuration Word Access” for more information on accessing these memory locations. For more information on checksum calculation, see the “PIC16F193X/LF193X/PIC16F194X/LF194X/PIC16LF 190X Memory Programming Specification” (DS41397). DS40001455F-page 36  2011-2016 Microchip Technology Inc. PIC16LF1902/3 4.5 Device ID and Revision ID The memory location 8006h is where the Device ID and Revision ID are stored. The upper nine bits hold the Device ID. The lower five bits hold the Revision ID. See Section 10.4 “User ID, Device ID and Configuration Word Access” for more information on accessing these memory locations. Development tools, such as device programmers and debuggers, may be used to read the Device ID and Revision ID. REGISTER 4-3: DEVICEID: DEVICE ID REGISTER R R R R R R DEV bit 13 R R bit 8 R R R DEV R R R REV bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘1’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared P = Programmable bit bit 13-5 DEV: Device ID bits DEVICEID Values Device bit 4-0 DEV REV PIC16LF1902 01 1100 001 x xxxx PIC16LF1903 01 1100 000 x xxxx REV: Revision ID bits These bits are used to identify the revision (see Table under DEV above).  2011-2016 Microchip Technology Inc. DS40001455F-page 37 PIC16LF1902/3 5.0 A simplified block diagram of the On-Chip Reset Circuit is shown in Figure 5-1. RESETS There are multiple ways to reset this device: • • • • • • • • • Power-on Reset (POR) Brown-out Reset (BOR) Low-Power Brown-out Reset (LPBOR) MCLR Reset WDT Reset RESET instruction Stack Overflow Stack Underflow Programming mode exit To allow VDD to stabilize, an optional power-up timer can be enabled to extend the Reset time after a BOR or POR event. FIGURE 5-1: SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT Rev. 10-000006A 8/14/2013 ICSP™ Programming Mode Exit RESET Instruction Stack Underflow Stack Overlfow MCLRE VPP/MCLR Sleep WDT Time-out Device Reset Power-on Reset VDD BOR Active(1) Brown-out Reset LPBOR Reset Note 1: R LFINTOSC Power-up Timer PWRTE See Table 5-1 for BOR active conditions. DS40001455F-page 38  2011-2016 Microchip Technology Inc. PIC16LF1902/3 5.1 Power-on Reset (POR) 5.2 Brown-Out Reset (BOR) The POR circuit holds the device in Reset until VDD has reached an acceptable level for minimum operation. Slow rising VDD, fast operating speeds or analog performance may require greater than minimum VDD. The PWRT, BOR or MCLR features can be used to extend the start-up period until all device operation conditions have been met. The BOR circuit holds the device in Reset when VDD reaches a selectable minimum level. Between the POR and BOR, complete voltage range coverage for execution protection can be implemented. 5.1.1 • • • • POWER-UP TIMER (PWRT) The Power-up Timer provides a nominal 64 ms time-out on POR or Brown-out Reset. The device is held in Reset as long as PWRT is active. The PWRT delay allows additional time for the VDD to rise to an acceptable level. The Power-up Timer is enabled by clearing the PWRTE bit in Configuration Word 1. The Power-up Timer starts after the release of the POR and BOR. For additional information, refer to Application Note AN607, “Power-up Trouble Shooting” (DS00607). TABLE 5-1: The Brown-out Reset module has four operating modes controlled by the BOREN bits in Configuration Word 1. The four operating modes are: BOR is always on BOR is off when in Sleep BOR is controlled by software BOR is always off Refer to Table 5-1 for more information. The Brown-out Reset voltage level is selectable by configuring the BORV bit in Configuration Word 2. A VDD noise rejection filter prevents the BOR from triggering on small events. If VDD falls below VBOR for a duration greater than parameter TBORDC, the device will reset. See Figure 5-2 for more information. BOR OPERATING MODES BOREN SBOREN Device Mode BOR Mode Device Operation Device Operation upon wake- up from upon release of POR Sleep 11 X X Active Waits for BOR ready(1) Awake Active 10 X Sleep Disabled 1 X Active Waits for BOR ready(1) 0 X Disabled Begins immediately X X Disabled Begins immediately 01 00 Waits for BOR ready Note 1: In these specific cases, “Release of POR” and “Wake-up from Sleep”, there is no delay in start-up. The BOR ready flag, (BORRDY = 1), will be set before the CPU is ready to execute instructions because the BOR circuit is forced on by the BOREN bits. 5.2.1 BOR IS ALWAYS ON 5.2.3 BOR CONTROLLED BY SOFTWARE When the BOREN bits of Configuration Word 1 are set to ‘11’, the BOR is always on. The device start-up will be delayed until the BOR is ready and VDD is higher than the BOR threshold. When the BOREN bits of Configuration Word 1 are set to ‘01’, the BOR is controlled by the SBOREN bit of the BORCON register. The device start-up is not delayed by the BOR ready condition or the VDD level. BOR protection is active during Sleep. The BOR does not delay wake-up from Sleep. BOR protection begins as soon as the BOR circuit is ready. The status of the BOR circuit is reflected in the BORRDY bit of the BORCON register. 5.2.2 BOR IS OFF IN SLEEP BOR protection is unchanged by Sleep. When the BOREN bits of Configuration Word 1 are set to ‘10’, the BOR is on, except in Sleep. The device start-up will be delayed until the BOR is ready and VDD is higher than the BOR threshold. BOR protection is not active during Sleep. The device wake-up will be delayed until the BOR is ready.  2011-2016 Microchip Technology Inc. DS40001455F-page 39 PIC16LF1902/3 FIGURE 5-2: BROWN-OUT SITUATIONS VDD VBOR Internal Reset TPWRT(1) VDD VBOR Internal Reset < TPWRT TPWRT(1) VDD VBOR Internal Reset Note 1: TPWRT(1) TPWRT delay only if PWRTE bit is programmed to ‘0’. REGISTER 5-1: BORCON: BROWN-OUT RESET CONTROL REGISTER R/W-1/u R/W-0/u U-0 U-0 U-0 U-0 U-0 R-q/u SBOREN BORFS — — — — — BORRDY bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared q = Value depends on condition bit 7 SBOREN: Software Brown-out Reset Enable bit If BOREN in Configuration Word 1  01: SBOREN is read/write, but has no effect on the BOR. If BOREN in Configuration Word 1 = 01: 1 = BOR Enabled 0 = BOR Disabled bit 6 BORFS: Brown-out Reset Fast Start bit(1) If BOREN = 11 (Always on) or BOREN = 00 (Always off) BORFS is Read/Write, but has no effect. If BOREN = 10 (Disabled in Sleep) or BOREN = 01 (Under software control): 1 = Band gap is forced on always (covers sleep/wake-up/operating cases) 0 = Band gap operates normally, and may turn off bit 5-1 Unimplemented: Read as ‘0’ bit 0 BORRDY: Brown-out Reset Circuit Ready Status bit 1 = The Brown-out Reset circuit is active 0 = The Brown-out Reset circuit is inactive DS40001455F-page 40  2011-2016 Microchip Technology Inc. PIC16LF1902/3 5.3 Low-Power Brown-out Reset (LPBOR) The Low-Power Brown-Out Reset (LPBOR) is an essential part of the Reset subsystem. Refer to Figure 5-1 to see how the BOR interacts with other modules. The LPBOR is used to monitor the external VDD pin. When too low of a voltage is detected, the device is held in Reset. When this occurs, a register bit (BOR) is changed to indicate that a BOR Reset has occurred. The same bit is set for both the BOR and the LPBOR. Refer to Register 5-2. 5.3.1 ENABLING LPBOR The LPBOR is controlled by the LPBOR bit of Configuration Word 2. When the device is erased, the LPBOR module defaults to disabled. 5.3.1.1 LPBOR Module Output The output of the LPBOR module is a signal indicating whether or not a Reset is to be asserted. This signal is to be OR’d together with the Reset signal of the BOR module to provide the generic BOR signal which goes to the PCON register and to the power control block. 5.4 MCLR 5.5 Watchdog Timer (WDT) Reset The Watchdog Timer generates a Reset if the firmware does not issue a CLRWDT instruction within the time-out period. The TO and PD bits in the STATUS register are changed to indicate the WDT Reset. See Section 9.0 “Watchdog Timer” for more information. 5.6 RESET Instruction A RESET instruction will cause a device Reset. The RI bit in the PCON register will be set to ‘0’. See Table 5-4 for default conditions after a RESET instruction has occurred. 5.7 Stack Overflow/Underflow Reset The device can reset when the Stack Overflows or Underflows. The STKOVF or STKUNF bits of the PCON register indicate the Reset condition. These Resets are enabled by setting the STVREN bit in Configuration Word 2. See Section 5.7 “Stack Overflow/Underflow Reset” for more information. 5.8 Programming Mode Exit Upon exit of Programming mode, the device will behave as if a POR had just occurred. The MCLR is an optional external input that can reset the device. The MCLR function is controlled by the MCLRE bit of Configuration Word 1 and the LVP bit of Configuration Word 2 (Table 5-2). 5.9 TABLE 5-2: The Power-up Timer is controlled by the PWRTE bit of Configuration Word 1. MCLR CONFIGURATION MCLRE LVP MCLR 0 0 Disabled 1 0 Enabled x 1 Enabled 5.4.1 MCLR ENABLED When MCLR is enabled and the pin is held low, the device is held in Reset. The MCLR pin is connected to VDD through an internal weak pull-up. The device has a noise filter in the MCLR Reset path. The filter will detect and ignore small pulses. Note: 5.4.2 A Reset does not drive the MCLR pin low. MCLR DISABLED When MCLR is disabled, the pin functions as a general purpose input and the internal weak pull-up is under software control. See Section 11.4 “PORTE Registers” for more information.  2011-2016 Microchip Technology Inc. Power-Up Timer The Power-up Timer optionally delays device execution after a BOR or POR event. This timer is typically used to allow VDD to stabilize before allowing the device to start running. 5.10 Start-up Sequence Upon the release of a POR or BOR, the following must occur before the device will begin executing: 1. 2. 3. Power-up Timer runs to completion (if enabled). Oscillator start-up timer runs to completion (if required for oscillator source). MCLR must be released (if enabled). The total time-out will vary based on oscillator configuration and Power-up Timer configuration. See Section 6.0 “Oscillator Module” for more information. The Power-up Timer and oscillator start-up timer run independently of MCLR Reset. If MCLR is kept low long enough, the Power-up Timer and oscillator start-up timer will expire. Upon bringing MCLR high, the device will begin execution immediately (see Figure 5-3). This is useful for testing purposes or to synchronize more than one device operating in parallel. DS40001455F-page 41 PIC16LF1902/3 FIGURE 5-3: RESET START-UP SEQUENCE VDD Internal POR TPWRT Power-Up Timer MCLR TMCLR Internal RESET Oscillator Modes External Crystal TOST Oscillator Start-Up Timer Oscillator FOSC Internal Oscillator Oscillator FOSC External Clock (EC) CLKIN FOSC DS40001455F-page 42  2011-2016 Microchip Technology Inc. PIC16LF1902/3 5.11 Determining the Cause of a Reset Upon any Reset, multiple bits in the STATUS and PCON register are updated to indicate the cause of the Reset. Table 5-3 and Table 5-4 show the Reset conditions of these registers. TABLE 5-3: RESET STATUS BITS AND THEIR SIGNIFICANCE STKOVF STKUNF RWDT RMCLR RI POR BOR TO PD Condition 0 0 1 1 1 0 x 1 1 Power-on Reset 0 0 1 1 1 0 x 0 x Illegal, TO is set on POR 0 0 1 1 1 0 x x 0 Illegal, PD is set on POR 0 0 u 1 1 u 0 1 1 Brown-out Reset u u 0 u u u u 0 u WDT Reset u u u u u u u 0 0 WDT Wake-up from Sleep u u u u u u u 1 0 Interrupt Wake-up from Sleep u u u 0 u u u u u MCLR Reset during normal operation u u u 0 u u u 1 0 MCLR Reset during Sleep u u u u 0 u u u u RESET Instruction Executed 1 u u u u u u u u Stack Overflow Reset (STVREN = 1) u 1 u u u u u u u Stack Underflow Reset (STVREN = 1) TABLE 5-4: RESET CONDITION FOR SPECIAL REGISTERS(2) Program Counter STATUS Register PCON Register Power-on Reset 0000h ---1 1000 00-1 110x MCLR Reset during normal operation 0000h ---u uuuu uu-u 0uuu MCLR Reset during Sleep 0000h ---1 0uuu uu-u 0uuu WDT Reset 0000h ---0 uuuu uu-0 uuuu WDT Wake-up from Sleep PC + 1 ---0 0uuu uu-u uuuu Brown-out Reset 0000h ---1 1uuu 00-1 11u0 ---1 0uuu uu-u uuuu ---u uuuu uu-u u0uu Condition Interrupt Wake-up from Sleep RESET Instruction Executed PC + 1 (1) 0000h Stack Overflow Reset (STVREN = 1) 0000h ---u uuuu 1u-u uuuu Stack Underflow Reset (STVREN = 1) 0000h ---u uuuu u1-u uuuu Legend: u = unchanged, x = unknown, - = unimplemented bit, reads as ‘0’. Note 1: When the wake-up is due to an interrupt and Global Enable bit (GIE) is set, the return address is pushed on the stack and PC is loaded with the interrupt vector (0004h) after execution of PC + 1. 2: If a Status bit is not implemented, that bit will be read as ‘0’.  2011-2016 Microchip Technology Inc. DS40001455F-page 43 PIC16LF1902/3 5.12 Power Control (PCON) Register The PCON register bits are shown in Register 5-2. The Power Control (PCON) register contains flag bits to differentiate between a: • • • • • • • Power-on Reset (POR) Brown-out Reset (BOR) Reset Instruction Reset (RI) MCLR Reset (RMCLR) Watchdog Timer Reset (RWDT) Stack Underflow Reset (STKUNF) Stack Overflow Reset (STKOVF) REGISTER 5-2: PCON: POWER CONTROL REGISTER R/W/HS-0/q R/W/HS-0/q U-0 STKOVF STKUNF — R/W/HC-1/q R/W/HC-1/q RWDT RMCLR R/W/HC-1/q R/W/HC-q/u R/W/HC-q/u RI POR BOR bit 7 bit 0 Legend: HC = Bit is cleared by hardware HS = Bit is set by hardware R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -m/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared q = Value depends on condition bit 7 STKOVF: Stack Overflow Flag bit 1 = A Stack Overflow occurred 0 = A Stack Overflow has not occurred or set to ‘0’ by firmware bit 6 STKUNF: Stack Underflow Flag bit 1 = A Stack Underflow occurred 0 = A Stack Underflow has not occurred or set to ‘0’ by firmware bit 5 Unimplemented: Read as ‘0’ bit 4 RWDT: Watchdog Timer Reset Flag bit 1 = A Watchdog Timer Reset has not occurred or set to ‘1’ by firmware 0 = A Watchdog Timer Reset has occurred (set to ‘0’ in hardware when a Watchdog Timer Reset) bit 3 RMCLR: MCLR Reset Flag bit 1 = A MCLR Reset has not occurred or set to ‘1’ by firmware 0 = A MCLR Reset has occurred (set to ‘0’ in hardware when a MCLR Reset occurs) bit 2 RI: RESET Instruction Flag bit 1 = A RESET instruction has not been executed or set to ‘1’ by firmware 0 = A RESET instruction has been executed (set to ‘0’ in hardware upon executing a RESET instruction) bit 1 POR: Power-on Reset Status bit 1 = No Power-on Reset occurred 0 = A Power-on Reset occurred (must be set in software after a Power-on Reset occurs) bit 0 BOR: Brown-out Reset Status bit 1 = No Brown-out Reset occurred 0 = A Brown-out Reset occurred (must be set in software after a Power-on Reset or Brown-out Reset occurs) DS40001455F-page 44  2011-2016 Microchip Technology Inc. PIC16LF1902/3 TABLE 5-5: SUMMARY OF REGISTERS ASSOCIATED WITH RESETS Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Register on Page BORCON SBOREN BORFS — — — — — BORRDY 40 PCON STKOVF STKUNF — RWDT RMCLR RI POR BOR 44 STATUS — — — TO PD Z DC C 16 WDTCON — — SWDTEN 70 WDTPS Legend: — = unimplemented location, read as ‘0’. Shaded cells are not used by Resets.  2011-2016 Microchip Technology Inc. DS40001455F-page 45 PIC16LF1902/3 6.0 OSCILLATOR MODULE 6.1 Overview The oscillator module has a wide variety of clock sources and selection features that allow it to be used in a wide range of applications while maximizing performance and minimizing power consumption. Figure 6-1 illustrates a block diagram of the oscillator module. Clock sources can be supplied from external clock circuits. In addition, the system clock source can be supplied from one of two internal oscillators, with a choice of speeds selectable via software. Additional clock features include: • Selectable system clock source between external or internal sources via software. • Fast start-up oscillator allows internal circuits to power up and stabilize before switching to the 16 MHz HFINTOSC The oscillator module can be configured in one of the following Clock modes: 1. 2. 3. 4. ECL – External Clock Low-Power mode (0 MHz to 0.5 MHz) ECM – External Clock Medium-Power mode (0.5 MHz to 4 MHz) ECH – External Clock High-Power mode (4 MHz to 32 MHz) INTOSC – Internal oscillator (31 kHz to 16 MHz). Clock Source modes are selected by the FOSC bits in the Configuration Word 1. The FOSC bits determine the type of oscillator that will be used when the device is first powered. The EC Clock mode relies on an external logic level signal as the device clock source. The INTOSC internal oscillator block produces a low and high frequency clock source, designated LFINTOSC and HFINTOSC. (see Internal Oscillator Block, Figure 6-1). A wide selection of device clock frequencies may be derived from these two clock sources. DS40001455F-page 46  2011-2016 Microchip Technology Inc. PIC16LF1902/3 SIMPLIFIED PIC® MCU CLOCK SOURCE BLOCK DIAGRAM FIGURE 6-1: Low-Power Mode Event Switch (SCS) CLKIN EC 2 CLKIN Primary Clock 00 T1CKI/ T1OSO T1OSI Secondary Oscillator (T1OSC) Secondary Clock INTOSC 01 1x Clock Switch MUX Secondary Oscillator Internal Oscillator IRCF 4 Start-Up Osc LF-INTOSC (31 kHz)  2011-2016 Microchip Technology Inc. INTOSC Divide Circuit 16 MHz Primary Osc /1 /2 /4 /8 /16 HF-16 MHz /32 HF-500 kHz /64 HF-250 kHz HF-8 MHz HF-4 MHz HF-2 MHz HF-1 MHz /128 HF-125 kHz /256 HF-62.5 kHz /512 HF-31.25 kHz LF-31 kHz 1111 1110 1101 1100 1011 1010/ 0111 1001/ 0110 1000/ 0101 0100 0011 0010 0001 0000 Internal Oscillator MUX Start-up Control Logic 4 DS40001455F-page 47 PIC16LF1902/3 6.2 Clock Source Types Clock sources can be classified as external or internal. External clock sources rely on external circuitry for the clock source to function. An example is: oscillator module (EC mode) circuit. Internal clock sources are contained internally within the oscillator module. The internal oscillator block has two internal oscillators that are used to generate the internal system clock sources: the 16 MHz High-Frequency Internal Oscillator and the 31 kHz Low-Frequency Internal Oscillator (LFINTOSC). The system clock can be selected between external or internal clock sources via the System Clock Select (SCS) bits in the OSCCON register. See Section 6.3 “Clock Switching” for additional information. 6.2.1 EXTERNAL CLOCK SOURCES An external clock source can be used as the device system clock by performing one of the following actions: There is no delay in operation after a Power-on Reset (POR) or wake-up from Sleep. Because the PIC® MCU design is fully static, stopping the external clock input will have the effect of halting the device while leaving all data intact. Upon restarting the external clock, the device will resume operation as if no time had elapsed. FIGURE 6-2: EXTERNAL CLOCK (EC) MODE OPERATION CLKIN Clock from Ext. System PIC® MCU FOSC/4 or I/O(1) Note 1: CLKOUT Output depends upon CLKOUTEN bit of the Configuration Word 1. • Program the FOSC bits in the Configuration Word 1 to select an external clock source that will be used as the default system clock upon a device Reset. • Write the SCS bits in the OSCCON register to switch the system clock source to: - Secondary oscillator during run-time, or - An external clock source determined by the value of the FOSC bits. See Section 6.3 “Clock Switching”for more information. 6.2.1.1 EC Mode The External Clock (EC) mode allows an externally generated logic level signal to be the system clock source. When operating in this mode, an external clock source is connected to the CLKIN input. CLKOUT is available for general purpose I/O or CLKOUT. Figure 6-2 shows the pin connections for EC mode. EC mode has three power modes to select from through Configuration Word 1: • High power, 4-20 MHz (FOSC = 11) • Medium power, 0.5-4 MHz (FOSC = 10) • Low power, 0-0.5 MHz (FOSC = 01) DS40001455F-page 48  2011-2016 Microchip Technology Inc. PIC16LF1902/3 6.2.1.2 6.2.2 Secondary Oscillator The secondary oscillator is a separate crystal oscillator that is associated with the Timer1 peripheral. It is optimized for timekeeping operations with a 32.768 kHz crystal connected between the T1CKI/T1OSO and T1OSI device pins. The secondary oscillator can be used as an alternate system clock source and can be selected during run-time using clock switching. Refer to Section 6.3 “Clock Switching” for more information. FIGURE 6-3: QUARTZ CRYSTAL OPERATION (SECONDARY OSCILLATOR) PIC® The device may be configured to use the internal oscillator block as the system clock by performing one of the following actions: • Program the FOSC bits in Configuration Word 1 to select the INTOSC clock source, which will be used as the default system clock upon a device Reset. • Write the SCS bits in the OSCCON register to switch the system clock source to the internal oscillator during run-time. See Section 6.3 “Clock Switching”for more information. In INTOSC mode, CLKIN is available for general purpose I/O. CLKOUT is available for general purpose I/O or CLKOUT. The function of the CLKOUT pin is determined by the state of the CLKOUTEN bit in Configuration Word 1. MCU T1CKI/T1OSO C1 To Internal Logic 32.768 kHz Quartz Crystal The internal oscillator block has two independent oscillators that provides the internal system clock source. 1. 2. C2 T1OSI The HFINTOSC (High-Frequency Internal Oscillator) is factory calibrated and operates at 16 MHz. The LFINTOSC (Low-Frequency Internal Oscillator) is uncalibrated and operates at 31 kHz. 6.2.2.1 Note 1: Quartz crystal characteristics vary according to type, package and manufacturer. The user should consult the manufacturer data sheets for specifications and recommended application. 2: Always verify oscillator performance over the VDD and temperature range that is expected for the application. 3: For oscillator design assistance, reference the following Microchip Applications Notes: • AN826, “Crystal Oscillator Basics and Crystal Selection for rfPIC® and PIC® Devices” (DS00826) • AN849, “Basic PIC® Oscillator Design” (DS00849) • AN943, “Practical PIC® Oscillator Analysis and Design” (DS00943) • AN949, “Making Your Oscillator Work” (DS00949) • TB097, “Interfacing a Micro Crystal MS1V-T1K 32.768 kHz Tuning Fork Crystal to a PIC16F690/SS” (DS91097) • AN1288, “Design Practices for Low-Power External Oscillators” (DS01288)  2011-2016 Microchip Technology Inc. INTERNAL CLOCK SOURCES HFINTOSC The High-Frequency Internal Oscillator (HFINTOSC) is a factory calibrated 16 MHz internal clock source. The output of the HFINTOSC connects to a postscaler and multiplexer (see Figure 6-1). The frequency derived from the HFINTOSC can be selected via software using the IRCF bits of the OSCCON register. See Section 6.2.2.4 “Internal Oscillator Clock Switch Timing” for more information. The HFINTOSC is enabled by: • Configure the IRCF bits of the OSCCON register for the desired HF frequency, and • FOSC = 11, or • Set the System Clock Source (SCS) bits of the OSCCON register to ‘1x’. The High-Frequency Internal Oscillator Ready bit (HFIOFR) of the OSCSTAT register indicates when the HFINTOSC is running and can be utilized. The High-Frequency Internal Oscillator Status Stable bit (HFIOFS) of the OSCSTAT register indicates when the HFINTOSC is running within 0.5% of its final value. DS40001455F-page 49 PIC16LF1902/3 6.2.2.2 LFINTOSC The Low-Frequency Internal Oscillator (LFINTOSC) is an uncalibrated 31 kHz internal clock source. The output of the LFINTOSC connects to a multiplexer (see Figure 6-1). Select 31 kHz, via software, using the IRCF bits of the OSCCON register. See Section 6.2.2.4 “Internal Oscillator Clock Switch Timing” for more information. The LFINTOSC is also the frequency for the Power-up Timer (PWRT) and Watchdog Timer (WDT). The LFINTOSC is enabled by selecting 31 kHz (IRCF bits of the OSCCON register = 000) as the system clock source (SCS bits of the OSCCON register = 1x), or when any of the following are enabled: • Configure the IRCF bits of the OSCCON register for the desired LF frequency, and • FOSC = 01, or • Set the System Clock Source (SCS) bits of the OSCCON register to ‘1x’ Peripherals that use the LFINTOSC are: • Power-up Timer (PWRT) • Watchdog Timer (WDT) The Low-Frequency Internal Oscillator Ready bit (LFIOFR) of the OSCSTAT register indicates when the LFINTOSC is running and can be utilized. 6.2.2.3 Internal Oscillator Frequency Selection The system clock speed can be selected via software using the Internal Oscillator Frequency Select bits IRCF of the OSCCON register. The output of the 16 MHz HFINTOSC and 31 kHz LFINTOSC connects to a postscaler and multiplexer (see Figure 6-1). The Internal Oscillator Frequency Select bits IRCF of the OSCCON register select the frequency output of the internal oscillators. One of the following frequencies can be selected via software: • • • • • • • • • • • 16 MHz 8 MHz 4 MHz 2 MHz 1 MHz 500 kHz (Default after Reset) 250 kHz 125 kHz 62.5 kHz 31.25 kHz 31 kHz (LFINTOSC) DS40001455F-page 50 Note: Following any Reset, the IRCF bits of the OSCCON register are set to ‘0111’ and the frequency selection is set to 500 kHz. The user can modify the IRCF bits to select a different frequency. The IRCF bits of the OSCCON register allow duplicate selections for some frequencies. These duplicate choices can offer system design trade-offs. Lower power consumption can be obtained when changing oscillator sources for a given frequency. Faster transition times can be obtained between frequency changes that use the same oscillator source. 6.2.2.4 Internal Oscillator Clock Switch Timing When switching between the HFINTOSC and the LFINTOSC, the new oscillator may already be shut down to save power (see Figure 6-4). If this is the case, there is a delay after the IRCF bits of the OSCCON register are modified before the frequency selection takes place. The OSCSTAT register will reflect the current active status of the HFINTOSC and LFINTOSC oscillators. The sequence of a frequency selection is as follows: 1. 2. 3. 4. 5. 6. 7. IRCF bits of the OSCCON register are modified. If the new clock is shut down, a clock start-up delay is started. Clock switch circuitry waits for a falling edge of the current clock. The current clock is held low and the clock switch circuitry waits for a rising edge in the new clock. The new clock is now active. The OSCSTAT register is updated as required. Clock switch is complete. See Figure 6-4 for more details. If the internal oscillator speed is switched between two clocks of the same source, there is no start-up delay before the new frequency is selected. Clock switching time delays are shown in Table 6-2. Start-up delay specifications are located in the oscillator tables of Section 21.0 “Electrical Specifications”  2011-2016 Microchip Technology Inc. PIC16LF1902/3 FIGURE 6-4: INTERNAL OSCILLATOR SWITCH TIMING HFINTOSC LFINTOSC (WDT disabled) HFINTOSC Oscillator Delay(1) 2-cycle Sync Running LFINTOSC IRCF 0 0 System Clock LFINTOSC (WDT enabled) HFINTOSC HFINTOSC 2-cycle Sync Running LFINTOSC 0 IRCF 0 System Clock LFINTOSC HFINTOSC LFINTOSC turns off unless WDT is enabled LFINTOSC Oscillator Delay(1) 2-cycle Sync Running HFINTOSC IRCF 0 =0 System Clock Note 1: See Table 6-1 for more information. TABLE 6-1: Switch From Any clock source OSCILLATOR SWITCHING DELAYS Switch To Oscillator Delay LFINTOSC 1 cycle of each clock source HFINTOSC 2 s (approx.) ECH, ECM, ECL 2 cycles Secondary Oscillator 1024 Secondary Oscillator Cycles  2011-2016 Microchip Technology Inc. DS40001455F-page 51 PIC16LF1902/3 6.3 Clock Switching 6.3.3 SECONDARY OSCILLATOR The system clock source can be switched between external and internal clock sources via software using the System Clock Select (SCS) bits of the OSCCON register. The following clock sources can be selected using the SCS bits: The secondary oscillator is a separate crystal oscillator associated with the Timer1 peripheral. It is optimized for timekeeping operations with a 32.768 kHz crystal connected between the T1OSI and T1CKI/T1OSO device pins. • Default system oscillator determined by FOSC bits in Configuration Word 1 • Secondary oscillator 32 kHz crystal • Internal Oscillator Block (INTOSC) The secondary oscillator is enabled using the T1OSCEN control bit in the T1CON register. See Section 17.0 “Timer1 Module with Gate Control” for more information about the Timer1 peripheral. 6.3.1 SYSTEM CLOCK SELECT (SCS) BITS The System Clock Select (SCS) bits of the OSCCON register selects the system clock source that is used for the CPU and peripherals. • When the SCS bits of the OSCCON register = 00, the system clock source is determined by value of the FOSC bits in the Configuration Word 1. • When the SCS bits of the OSCCON register = 01, the system clock source is the secondary oscillator. • When the SCS bits of the OSCCON register = 1x, the system clock source is chosen by the internal oscillator frequency selected by the IRCF bits of the OSCCON register. After a Reset, the SCS bits of the OSCCON register are always cleared. 6.3.4 SECONDARY OSCILLATOR READY (T1OSCR) BIT The user must ensure that the secondary oscillator is ready to be used before it is selected as a system clock source. The Secondary Oscillator Ready (T1OSCR) bit of the OSCSTAT register indicates whether the secondary oscillator is ready to be used. After the T1OSCR bit is set, the SCS bits can be configured to select the secondary oscillator. When switching between clock sources, a delay is required to allow the new clock to stabilize. These oscillator delays are shown in Table 6-2. 6.3.2 OSCILLATOR START-UP TIME-OUT STATUS (OSTS) BIT The Oscillator Start-up Time-out Status (OSTS) bit of the OSCSTAT register indicates whether the system clock is running from the external clock source, as defined by the FOSC bits in the Configuration Word 1, or from the internal clock source. DS40001455F-page 52  2011-2016 Microchip Technology Inc. PIC16LF1902/3 6.4 Oscillator Control Registers REGISTER 6-1: U-0 OSCCON: OSCILLATOR CONTROL REGISTER R/W-0/0 R/W-1/1 R/W-1/1 R/W-1/1 IRCF — U-0 R/W-0/0 — bit 7 R/W-0/0 SCS bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7 Unimplemented: Read as ‘0’ bit 6-3 IRCF: Internal Oscillator Frequency Select bits 000x = 31 kHz LF 001x = 31.25 kHz 0100 = 62.5 kHz 0101 = 125 kHz 0110 = 250 kHz 0111 = 500 kHz (default upon Reset) 1000 = 125 kHz(1) 1001 = 250 kHz(1) 1010 = 500 kHz(1) 1011 = 1 MHz 1100 = 2 MHz 1101 = 4 MHz 1110 = 8 MHz 1111 = 16 MHz bit 2 Unimplemented: Read as ‘0’ bit 1-0 SCS: System Clock Select bits 1x = Internal oscillator block 01 = Secondary oscillator 00 = Clock determined by FOSC in Configuration Word 1. Note 1: Duplicate frequency derived from HFINTOSC.  2011-2016 Microchip Technology Inc. DS40001455F-page 53 PIC16LF1902/3 REGISTER 6-2: OSCSTAT: OSCILLATOR STATUS REGISTER R-1/q U-0 R-q/q R-0/q U-0 U-0 R-0/0 R-0/q T1OSCR — OSTS HFIOFR — — LFIOFR HFIOFS bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared q = Conditional bit 7 T1OSCR: Timer1 Oscillator Ready bit If T1OSCEN = 1: 1 = Timer1 oscillator is ready 0 = Timer1 oscillator is not ready If T1OSCEN = 0: 1 = Timer1 clock source is always ready bit 6 Unimplemented: Read as ‘0’ bit 5 OSTS: Oscillator Start-up Time-out Status bit 1 = Running from the external clock source (EC) 0 = Running from an internal oscillator (FOSC = 00) bit 4 HFIOFR: High-Frequency Internal Oscillator Ready bit 1 = HFINTOSC is ready 0 = HFINTOSC is not ready bit 3-2 Unimplemented: Read as ‘0’ bit 1 LFIOFR: Low-Frequency Internal Oscillator Ready bit 1 = LFINTOSC is ready 0 = LFINTOSC is not ready bit 0 HFIOFS: High-Frequency Internal Oscillator Stable bit 1 = HFINTOSC 16 MHz oscillator is stable and is driving the INTOSC 0 = HFINTOSC 16 MHz oscillator is not stable, the Start-up Oscillator is driving INTOSC TABLE 6-2: SUMMARY OF REGISTERS ASSOCIATED WITH CLOCK SOURCES Name Bit 7 Bit 6 OSCCON — OSCSTAT T1OSCR T1CON Legend: CONFIG1 Legend: Bit 4 Bit 3 IRCF — OSTS TMR1CS Bit 2 Bit 1 — HFIOFR T1CKPS Bit 0 SCS Register on Page 53 — — LFIOFR HFIOFS 54 T1OSCEN T1SYNC — TMR1ON 130 — = unimplemented location, read as ‘0’. Shaded cells are not used by clock sources. TABLE 6-3: Name Bit 5 Bits SUMMARY OF CONFIGURATION WORD WITH CLOCK SOURCES Bit -/7 Bit -/6 Bit 13/5 Bit 12/4 Bit 11/3 — CLKOUTEN 13:8 — — — 7:0 CP MCLRE PWRTE WDTE Bit 10/2 Bit 9/1 BOREN — Bit 8/0 — FOSC Register on Page 34 — = unimplemented location, read as ‘0’. Shaded cells are not used by clock sources. DS40001455F-page 54  2011-2016 Microchip Technology Inc. PIC16LF1902/3 7.0 A block diagram of the interrupt logic is shown in Figure 7.1 and Figure 7.1. INTERRUPTS The interrupt feature allows certain events to preempt normal program flow. Firmware is used to determine the source of the interrupt and act accordingly. Some interrupts can be configured to wake the MCU from Sleep mode. This chapter contains the following information for Interrupts: • • • • • Operation Interrupt Latency Interrupts During Sleep INT Pin Automatic Context Saving Many peripherals produce Interrupts. Refer to the corresponding chapters for details. FIGURE 7-1: INTERRUPT LOGIC TMR0IF TMR0IE Peripheral Interrupts (TMR1IF) PIR1 (TMR1IF) PIR1 Wake-up (If in Sleep mode) INTF INTE IOCIF IOCIE Interrupt to CPU PEIE PIRn PIEn  2011-2016 Microchip Technology Inc. GIE DS40001455F-page 55 PIC16LF1902/3 7.1 Operation Interrupts are disabled upon any device Reset. They are enabled by setting the following bits: • GIE bit of the INTCON register • Interrupt Enable bit(s) for the specific interrupt event(s) • PEIE bit of the INTCON register (if the Interrupt Enable bit of the interrupt event is contained in the PIE1 and PIE2 registers) 7.2 Interrupt Latency Interrupt latency is defined as the time from when the interrupt event occurs to the time code execution at the interrupt vector begins. The latency for synchronous interrupts is three or four instruction cycles. For asynchronous interrupts, the latency is three to five instruction cycles, depending on when the interrupt occurs. See Figure 7-2 and Figure 7.3 for more details. The INTCON, PIR1 and PIR2 registers record individual interrupts via interrupt flag bits. Interrupt flag bits will be set, regardless of the status of the GIE, PEIE and individual interrupt enable bits. The following events happen when an interrupt event occurs while the GIE bit is set: • Current prefetched instruction is flushed • GIE bit is cleared • Current Program Counter (PC) is pushed onto the stack • Critical registers are automatically saved to the shadow registers (See Section 7.5 “Automatic Context Saving”) • PC is loaded with the interrupt vector 0004h The firmware within the Interrupt Service Routine (ISR) should determine the source of the interrupt by polling the interrupt flag bits. The interrupt flag bits must be cleared before exiting the ISR to avoid repeated interrupts. Because the GIE bit is cleared, any interrupt that occurs while executing the ISR will be recorded through its interrupt flag, but will not cause the processor to redirect to the interrupt vector. The RETFIE instruction exits the ISR by popping the previous address from the stack, restoring the saved context from the shadow registers and setting the GIE bit. For additional information on a specific interrupt’s operation, refer to its peripheral chapter. Note 1: Individual interrupt flag bits are set, regardless of the state of any other enable bits. 2: All interrupts will be ignored while the GIE bit is cleared. Any interrupt occurring while the GIE bit is clear will be serviced when the GIE bit is set again. DS40001455F-page 56  2011-2016 Microchip Technology Inc. PIC16LF1902/3 FIGURE 7-2: INTERRUPT LATENCY CLKIN Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 CLKOUT Interrupt Sampled during Q1 Interrupt GIE PC Execute PC-1 PC 1 Cycle Instruction at PC PC+1 0004h 0005h Inst(PC) NOP NOP Inst(0004h) PC+1/FSR ADDR New PC/ PC+1 0004h 0005h Inst(PC) NOP NOP Inst(0004h) FSR ADDR PC+1 PC+2 0004h 0005h INST(PC) NOP NOP NOP Inst(0004h) Inst(0005h) FSR ADDR PC+1 0004h 0005h INST(PC) NOP NOP Inst(0004h) Interrupt GIE PC Execute PC-1 PC 2 Cycle Instruction at PC Interrupt GIE PC Execute PC-1 PC 3 Cycle Instruction at PC Interrupt GIE PC Execute PC-1 PC 3 Cycle Instruction at PC  2011-2016 Microchip Technology Inc. PC+2 NOP NOP DS40001455F-page 57 PIC16LF1902/3 FIGURE 7-3: INT PIN INTERRUPT TIMING Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 CLKIN CLKOUT (3) (4) INT pin (1) (1) INTF Interrupt Latency (2) (5) GIE INSTRUCTION FLOW PC Instruction Fetched Instruction Executed Note 1: PC Inst (PC) Inst (PC – 1) PC + 1 Inst (PC + 1) Inst (PC) PC + 1 — Dummy Cycle 0004h 0005h Inst (0004h) Inst (0005h) Dummy Cycle Inst (0004h) INTF flag is sampled here (every Q1). 2: Asynchronous interrupt latency = 3-5 TCY. Synchronous latency = 3-4 TCY, where TCY = instruction cycle time. Latency is the same whether Inst (PC) is a single cycle or a 2-cycle instruction. 3: CLKOUT not available in all Oscillator modes. 4: For minimum width of INT pulse, refer to AC specifications in Section 21.0 “Electrical Specifications”. 5: INTF is enabled to be set any time during the Q4-Q1 cycles. DS40001455F-page 58  2011-2016 Microchip Technology Inc. PIC16LF1902/3 7.3 Interrupts During Sleep Some interrupts can be used to wake from Sleep. To wake from Sleep, the peripheral must be able to operate without the system clock. The interrupt source must have the appropriate Interrupt Enable bit(s) set prior to entering Sleep. On waking from Sleep, if the GIE bit is also set, the processor will branch to the interrupt vector. Otherwise, the processor will continue executing instructions after the SLEEP instruction. The instruction directly after the SLEEP instruction will always be executed before branching to the ISR. Refer to the Section 8.0 “Power-Down Mode (Sleep)” for more details. 7.4 INT Pin The INT pin can be used to generate an asynchronous edge-triggered interrupt. This interrupt is enabled by setting the INTE bit of the INTCON register. The INTEDG bit of the OPTION_REG register determines on which edge the interrupt will occur. When the INTEDG bit is set, the rising edge will cause the interrupt. When the INTEDG bit is clear, the falling edge will cause the interrupt. The INTF bit of the INTCON register will be set when a valid edge appears on the INT pin. If the GIE and INTE bits are also set, the processor will redirect program execution to the interrupt vector. 7.5 Automatic Context Saving Upon entering an interrupt, the return PC address is saved on the stack. Additionally, the following registers are automatically saved in the Shadow registers: • • • • • W register STATUS register (except for TO and PD) BSR register FSR registers PCLATH register Upon exiting the Interrupt Service Routine, these registers are automatically restored. Any modifications to these registers during the ISR will be lost. If modifications to any of these registers are desired, the corresponding Shadow register should be modified and the value will be restored when exiting the ISR. The Shadow registers are available in Bank 31 and are readable and writable. Depending on the user’s application, other registers may also need to be saved.  2011-2016 Microchip Technology Inc. DS40001455F-page 59 PIC16LF1902/3 7.6 Interrupt Control Registers Note: 7.6.1 INTCON REGISTER The INTCON register is a readable and writable register, which contains the various enable and flag bits for TMR0 register overflow, interrupt-on-change and external INT pin interrupts. REGISTER 7-1: Interrupt flag bits are set when an interrupt condition occurs, regardless of the state of its corresponding enable bit or the Global Enable bit, GIE of the INTCON register. User software should ensure the appropriate interrupt flag bits are clear prior to enabling an interrupt. INTCON: INTERRUPT CONTROL REGISTER R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 R-0/0 GIE PEIE TMR0IE INTE IOCIE TMR0IF INTF IOCIF bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7 GIE: Global Interrupt Enable bit 1 = Enables all active interrupts 0 = Disables all interrupts bit 6 PEIE: Peripheral Interrupt Enable bit 1 = Enables all active peripheral interrupts 0 = Disables all peripheral interrupts bit 5 TMR0IE: Timer0 Overflow Interrupt Enable bit 1 = Enables the Timer0 interrupt 0 = Disables the Timer0 interrupt bit 4 INTE: INT External Interrupt Enable bit 1 = Enables the INT external interrupt 0 = Disables the INT external interrupt bit 3 IOCIE: Interrupt-on-Change Interrupt Enable bit 1 = Enables the interrupt-on-change interrupt 0 = Disables the interrupt-on-change interrupt bit 2 TMR0IF: Timer0 Overflow Interrupt Flag bit 1 = TMR0 register has overflowed 0 = TMR0 register did not overflow bit 1 INTF: INT External Interrupt Flag bit 1 = The INT external interrupt occurred 0 = The INT external interrupt did not occur bit 0 IOCIF: Interrupt-on-Change Interrupt Flag bit 1 = When at least one of the interrupt-on-change pins changed state 0 = None of the interrupt-on-change pins have changed state DS40001455F-page 60  2011-2016 Microchip Technology Inc. PIC16LF1902/3 7.6.2 PIE1 REGISTER The PIE1 register contains the interrupt enable bits, as shown in Register 7-2. REGISTER 7-2: R/W-0/0 TMR1GIE Note: Bit PEIE of the INTCON register must be set to enable any peripheral interrupt. PIE1: PERIPHERAL INTERRUPT ENABLE REGISTER 1 R/W-0/0 U-0 U-0 U-0 U-0 U-0 R/W-0/0 ADIE — — — — — TMR1IE bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7 TMR1GIE: Timer1 Gate Interrupt Enable bit 1 = Enables the Timer1 Gate Acquisition interrupt 0 = Disables the Timer1 Gate Acquisition interrupt bit 6 ADIE: A/D Converter (ADC) Interrupt Enable bit 1 = Enables the ADC interrupt 0 = Disables the ADC interrupt bit 5-1 Unimplemented: Read as ‘0’ bit 0 TMR1IE: Timer1 Overflow Interrupt Enable bit 1 = Enables the Timer1 overflow interrupt 0 = Disables the Timer1 overflow interrupt  2011-2016 Microchip Technology Inc. DS40001455F-page 61 PIC16LF1902/3 7.6.3 PIE2 REGISTER The PIE2 register contains the interrupt enable bits, as shown in Register 7-3. REGISTER 7-3: Note: Bit PEIE of the INTCON register must be set to enable any peripheral interrupt. PIE2: PERIPHERAL INTERRUPT ENABLE REGISTER 2 U-0 U-0 U-0 U-0 U-0 R/W-0/0 U-0 U-0 — — — — — LCDIE — — bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-3 Unimplemented: Read as ‘0’ bit 2 LCDIE: LCD Module Interrupt Enable bit 1 = Enables the LCD module interrupt 0 = Disables the LCD module interrupt bit 1-0 Unimplemented: Read as ‘0’ DS40001455F-page 62  2011-2016 Microchip Technology Inc. PIC16LF1902/3 7.6.4 PIR1 REGISTER The PIR1 register contains the interrupt flag bits, as shown in Register 7-4. REGISTER 7-4: Note: Interrupt flag bits are set when an interrupt condition occurs, regardless of the state of its corresponding enable bit or the Global Enable bit, GIE, of the INTCON register. User software should ensure the appropriate interrupt flag bits are clear prior to enabling an interrupt. PIR1: PERIPHERAL INTERRUPT REQUEST REGISTER 1 R/W-0/0 R/W-0/0 U-0 U-0 U-0 U-0 U-0 R/W-0/0 TMR1GIF ADIF — — — — — TMR1IF bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7 TMR1GIF: Timer1 Gate Interrupt Flag bit 1 = Interrupt is pending 0 = Interrupt is not pending bit 6 ADIF: A/D Converter Interrupt Flag bit 1 = Interrupt is pending 0 = Interrupt is not pending bit 5-1 Unimplemented: Read as ‘0’ bit 0 TMR1IF: Timer1 Overflow Interrupt Flag bit 1 = Interrupt is pending 0 = Interrupt is not pending  2011-2016 Microchip Technology Inc. DS40001455F-page 63 PIC16LF1902/3 7.6.5 PIR2 REGISTER The PIR2 register contains the interrupt flag bits, as shown in Register 7-5. REGISTER 7-5: Note: Interrupt flag bits are set when an interrupt condition occurs, regardless of the state of its corresponding enable bit or the Global Enable bit, GIE, of the INTCON register. User software should ensure the appropriate interrupt flag bits are clear prior to enabling an interrupt. PIR2: PERIPHERAL INTERRUPT REQUEST REGISTER 2 U-0 U-0 U-0 U-0 U-0 R/W-0/0 U-0 U-0 — — — — — LCDIF — — bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-3 Unimplemented: Read as ‘0’ bit 2 LCDIF: LCD Module Interrupt Flag bit 1 = Interrupt is pending 0 = Interrupt is not pending bit 1-0 Unimplemented: Read as ‘0’ DS40001455F-page 64  2011-2016 Microchip Technology Inc. PIC16LF1902/3 TABLE 7-1: Name INTCON SUMMARY OF REGISTERS ASSOCIATED WITH INTERRUPTS Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Register on Page GIE PEIE TMR0IE INTE IOCIE TMR0IF INTF IOCIF 60 OPTION_REG WPUEN PIE1 TMR1GIE INTEDG TMR0CS TMR0SE PSA PS ADIE — — — — — 121 TMR1IE 61 PIE2 — — — — — LCDIE — — 62 PIR1 TMR1GIF ADIF — — — — — TMR1IF 63 PIR2 — — — — — LCDIF — — 64 Legend: — = unimplemented location, read as ‘0’. Shaded cells are not used by interrupts.  2011-2016 Microchip Technology Inc. DS40001455F-page 65 PIC16LF1902/3 8.0 POWER-DOWN MODE (SLEEP) 8.1 Wake-up from Sleep The Power-Down mode is entered by executing a SLEEP instruction. The device can wake-up from Sleep through one of the following events: Upon entering Sleep mode, the following conditions exist: 1. 2. 3. 4. 5. 6. 1. WDT will be cleared but keeps running, if enabled for operation during Sleep. 2. PD bit of the STATUS register is cleared. 3. TO bit of the STATUS register is set. 4. CPU clock is disabled. 5. 31 kHz LFINTOSC is unaffected and peripherals that operate from it may continue operation in Sleep. 6. Secondary oscillator is unaffected and peripherals that operate from it may continue operation in Sleep. 7. ADC is unaffected, if the dedicated FRC clock is selected. 8. Capacitive Sensing oscillator is unaffected. 9. I/O ports maintain the status they had before SLEEP was executed (driving high, low or high-impedance). 10. Resets other than WDT are not affected by Sleep mode. Refer to individual chapters for more details on peripheral operation during Sleep. To minimize current consumption, the following conditions should be considered: • • • • • • I/O pins should not be floating External circuitry sinking current from I/O pins Internal circuitry sourcing current from I/O pins Current draw from pins with internal weak pull-ups Modules using 31 kHz LFINTOSC Modules using Secondary oscillator External Reset input on MCLR pin, if enabled BOR Reset, if enabled POR Reset Watchdog Timer, if enabled Any external interrupt Interrupts by peripherals capable of running during Sleep (see individual peripheral for more information) The first three events will cause a device Reset. The last three events are considered a continuation of program execution. To determine whether a device Reset or wake-up event occurred, refer to Section 5.11, Determining the Cause of a Reset. When the SLEEP instruction is being executed, the next instruction (PC + 1) is prefetched. For the device to wake-up through an interrupt event, the corresponding interrupt enable bit must be enabled. Wake-up will occur regardless of the state of the GIE bit. If the GIE bit is disabled, the device continues execution at the instruction after the SLEEP instruction. If the GIE bit is enabled, the device executes the instruction after the SLEEP instruction, the device will then call the Interrupt Service Routine. In cases where the execution of the instruction following SLEEP is not desirable, the user should have a NOP after the SLEEP instruction. The WDT is cleared when the device wakes up from Sleep, regardless of the source of wake-up. I/O pins that are high-impedance inputs should be pulled to VDD or VSS externally to avoid switching currents caused by floating inputs. Examples of internal circuitry that might be sourcing current include the FVR module. See 13.0 “Fixed Voltage Reference (FVR)” for more information. DS40001455F-page 66  2011-2016 Microchip Technology Inc. PIC16LF1902/3 8.1.1 WAKE-UP USING INTERRUPTS When global interrupts are disabled (GIE cleared) and any interrupt source has both its interrupt enable bit and interrupt flag bit set, one of the following will occur: • If the interrupt occurs before the execution of a SLEEP instruction - SLEEP instruction will execute as a NOP. - WDT and WDT prescaler will not be cleared - TO bit of the STATUS register will not be set - PD bit of the STATUS register will not be cleared. FIGURE 8-1: • If the interrupt occurs during or after the execution of a SLEEP instruction - SLEEP instruction will be completely executed - Device will immediately wake-up from Sleep - WDT and WDT prescaler will be cleared - TO bit of the STATUS register will be set - PD bit of the STATUS register will be cleared. Even if the flag bits were checked before executing a SLEEP instruction, it may be possible for flag bits to become set before the SLEEP instruction completes. To determine whether a SLEEP instruction executed, test the PD bit. If the PD bit is set, the SLEEP instruction was executed as a NOP. WAKE-UP FROM SLEEP THROUGH INTERRUPT Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 CLKIN(1) CLKOUT(2) Interrupt flag Interrupt Latency (1) GIE bit (INTCON reg.) Processor in Sleep Instruction Flow PC PC Instruction Fetched Instruction Executed Note 1: PC + 1 Inst(PC) = Sleep Inst(PC - 1) PC + 2 PC + 2 PC + 2 Inst(PC + 1) Inst(PC + 2) Sleep Inst(PC + 1) Dummy Cycle 0004h 0005h Inst(0004h) Inst(0005h) Dummy Cycle Inst(0004h) GIE = 1 assumed. In this case after wake-up, the processor calls the ISR at 0004h. If GIE = 0, execution will continue in-line. TABLE 8-1: SUMMARY OF REGISTERS ASSOCIATED WITH POWER-DOWN MODE Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Register on Page INTCON GIE PEIE TMR0IE INTE IOCIE TMR0IF INTF IOCIF 60 IOCBF IOCBF7 IOCBF6 IOCBF5 IOCBF4 IOCBF3 IOCBF2 IOCBF1 IOCBF0 101 IOCBN IOCBN7 IOCBN6 IOCBN5 IOCBN4 IOCBN3 IOCBN2 IOCBN1 IOCBN0 101 IOCBP7 IOCBP6 IOCBP5 IOCBP4 IOCBP3 IOCBP2 IOCBP1 IOCBP0 101 TMR1GIE ADIE — — — — — TMR1IE 61 IOCBP PIE1 PIE2 — — — — — LCDIE — — 62 PIR1 TMR1GIF ADIF — — — — — TMR1IF 63 PIR2 — — — — — LCDIF — — 64 STATUS — — — TO PD Z DC C 16 — — SWDTEN 70 WDTCON Legend: WDTPS — = unimplemented location, read as ‘0’. Shaded cells are not used in Power-Down mode.  2011-2016 Microchip Technology Inc. DS40001455F-page 67 PIC16LF1902/3 9.0 WATCHDOG TIMER The Watchdog Timer is a system timer that generates a Reset if the firmware does not issue a CLRWDT instruction within the time-out period. The Watchdog Timer is typically used to recover the system from unexpected events. The WDT has the following features: • Independent clock source • Multiple operating modes - WDT is always on - WDT is off when in Sleep - WDT is controlled by software - WDT is always off • Configurable time-out period is from 1 ms to 256 seconds (typical) • Multiple Reset conditions • Operation during Sleep FIGURE 9-1: WATCHDOG TIMER BLOCK DIAGRAM WDTE = 01 SWDTEN WDTE = 11 LFINTOSC 23-bit Programmable Prescaler WDT WDT Time-out WDTE = 10 Sleep DS40001455F-page 68 WDTPS  2011-2016 Microchip Technology Inc. PIC16LF1902/3 9.1 Independent Clock Source 9.3 The WDT derives its time base from the 31 kHz LFINTOSC internal oscillator. Time intervals in this chapter are based on a nominal interval of 1 ms. See Section 21.0 “Electrical Specifications” for the LFINTOSC tolerances. The WDTPS bits of the WDTCON register set the time-out period from 1 ms to 256 seconds (nominal). After a Reset, the default time-out period is two seconds. 9.4 9.2 WDT Operating Modes The Watchdog Timer module has four operating modes controlled by the WDTE bits in Configuration Word 1. See Table 9-1. 9.2.1 WDT IS ALWAYS ON When the WDTE bits of Configuration Word 1 are set to ‘11’, the WDT is always on. WDT protection is active during Sleep. 9.2.2 WDT protection is not active during Sleep. WDT CONTROLLED BY SOFTWARE When the WDTE bits of Configuration Word 1 are set to ‘01’, the WDT is controlled by the SWDTEN bit of the WDTCON register. WDT protection is unchanged by Sleep. See Table 9-1 for more details. TABLE 9-1: WDT OPERATING MODES WDTE SWDTEN Device Mode WDT Mode 11 X X Active Awake Active 10 X Sleep Disabled 1 X 01 0 00 TABLE 9-2: X X Clearing the WDT The WDT is cleared when any of the following conditions occur: • • • • • • Any Reset CLRWDT instruction is executed Device enters Sleep Device wakes up from Sleep Oscillator fail event WDT is disabled See Table 9-2 for more information. WDT IS OFF IN SLEEP When the WDTE bits of Configuration Word 1 are set to ‘10’, the WDT is on, except in Sleep. 9.2.3 Time-Out Period 9.5 Operation During Sleep When the device enters Sleep, the WDT is cleared. If the WDT is enabled during Sleep, the WDT resumes counting. When the device exits Sleep, the WDT is cleared again. When a WDT time-out occurs while the device is in Sleep, no Reset is generated. Instead, the device wakes up and resumes operation. The TO and PD bits in the STATUS register are changed to indicate the event. See Section 3.0 “Memory Organization” and STATUS register (Register 3-1) for more information. Active Disabled Disabled WDT CLEARING CONDITIONS Conditions WDT WDTE = 00 WDTE = 01 and SWDTEN = 0 WDTE = 10 and enter Sleep CLRWDT Command Cleared Oscillator Fail Detected Exit Sleep + System Clock = T1OSC, EXTRC, INTOSC, EXTCLK Change INTOSC divider (IRCF bits)  2011-2016 Microchip Technology Inc. Unaffected DS40001455F-page 69 PIC16LF1902/3 9.6 Watchdog Control Register REGISTER 9-1: WDTCON: WATCHDOG TIMER CONTROL REGISTER U-0 U-0 — — R/W-0/0 R/W-1/1 R/W-0/0 R/W-1/1 R/W-1/1 WDTPS R/W-0/0 SWDTEN bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -m/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-6 Unimplemented: Read as ‘0’ bit 5-1 WDTPS: Watchdog Timer Period Select bits(1) Bit Value = Prescale Rate 00000 = 1:32 (Interval 1 ms nominal) 00001 = 1:64 (Interval 2 ms nominal) 00010 = 1:128 (Interval 4 ms nominal) 00011 = 1:256 (Interval 8 ms nominal) 00100 = 1:512 (Interval 16 ms nominal) 00101 = 1:1024 (Interval 32 ms nominal) 00110 = 1:2048 (Interval 64 ms nominal) 00111 = 1:4096 (Interval 128 ms nominal) 01000 = 1:8192 (Interval 256 ms nominal) 01001 = 1:16384 (Interval 512 ms nominal) 01010 = 1:32768 (Interval 1s nominal) 01011 = 1:65536 (Interval 2s nominal) (Reset value) 01100 = 1:131072 (217) (Interval 4s nominal) 01101 = 1:262144 (218) (Interval 8s nominal) 01110 = 1:524288 (219) (Interval 16s nominal) 01111 = 1:1048576 (220) (Interval 32s nominal) 10000 = 1:2097152 (221) (Interval 64s nominal) 10001 = 1:4194304 (222) (Interval 128s nominal) 10010 = 1:8388608 (223) (Interval 256s nominal) 10011 = Reserved. Results in minimum interval (1:32) • • • 11111 = Reserved. Results in minimum interval (1:32) bit 0 Note 1: SWDTEN: Software Enable/Disable for Watchdog Timer bit If WDTE = 00: This bit is ignored. If WDTE = 01: 1 = WDT is turned on 0 = WDT is turned off If WDTE = 1x: This bit is ignored. Times are approximate. WDT time is based on 31 kHz LFINTOSC. DS40001455F-page 70  2011-2016 Microchip Technology Inc. PIC16LF1902/3 TABLE 9-3: Name SUMMARY OF REGISTERS ASSOCIATED WITH WATCHDOG TIMER Bit 7 Bit 6 OSCCON — STATUS — — — — WDTCON Legend: CONFIG1 Legend: Bit 4 Bit 3 IRCF — Bit 2 — TO PD Bit 1 Bit 0 SCS Z DC WDTPS Register on Page 53 C 16 SWDTEN 70 x = unknown, u = unchanged, – = unimplemented locations read as ‘0’. Shaded cells are not used by Watchdog Timer. TABLE 9-4: Name Bit 5 SUMMARY OF CONFIGURATION WORD WITH WATCHDOG TIMER Bits Bit -/7 Bit -/6 Bit 13/5 Bit 12/4 Bit 11/3 13:8 — — — — CLKOUTEN 7:0 CP MCLRE PWRTE WDTE Bit 10/2 Bit 9/1 BOREN — Bit 8/0 — FOSC Register on Page 34 — = unimplemented location, read as ‘0’. Shaded cells are not used by Watchdog Timer.  2011-2016 Microchip Technology Inc. DS40001455F-page 71 PIC16LF1902/3 10.0 FLASH PROGRAM MEMORY CONTROL The Flash program memory is readable and writable during normal operation over the full VDD range. Program memory is indirectly addressed using Special Function Registers (SFRs). The SFRs used to access program memory are: • • • • • • PMCON1 PMCON2 PMDATL PMDATH PMADRL PMADRH When accessing the program memory, the PMDATH:PMDATL register pair forms a 2-byte word that holds the 14-bit data for read/write, and the PMADRH:PMADRL register pair forms a 2-byte word that holds the 15-bit address of the program memory location being read. The write time is controlled by an on-chip timer. The write/erase voltages are generated by an on-chip charge pump rated to operate over the operating voltage range of the device. The Flash Program Memory can be protected in two ways; by code protection (CP bit in Configuration Word 1) and write protection (WRT bits in Configuration Word 2). Code protection (CP = 0)(1), disables access, reading and writing, to the Flash Program Memory via external device programmers. Code protection does not affect the self-write and erase functionality. Code protection can only be reset by a device programmer performing a Bulk Erase to the device, clearing all Flash Program Memory, Configuration bits and User IDs. Write protection prohibits self-write and erase to a portion or all of the Flash Program Memory as defined by the bits WRT. Write protection does not affect a device programmers ability to read, write or erase the device. Note 1: Code protection of the entire Flash Program Memory array is enabled by clearing the CP bit of Configuration Word 1. 10.1 PMADRL and PMADRH Registers The PMADRH:PMADRL register pair can address up to a maximum of 32K words of program memory. When selecting a program address value, the MSB of the address is written to the PMADRH register and the LSB is written to the PMADRL register. DS40001455F-page 72 10.1.1 PMCON1 AND PMCON2 REGISTERS PMCON1 is the control register for Flash Program Memory accesses. Control bits RD and WR initiate read and write, respectively. These bits cannot be cleared, only set, in software. They are cleared by hardware at completion of the read or write operation. The inability to clear the WR bit in software prevents the accidental, premature termination of a write operation. The WREN bit, when set, will allow a write operation to occur. On power-up, the WREN bit is clear. The WRERR bit is set when a write operation is interrupted by a Reset during normal operation. In these situations, following Reset, the user can check the WRERR bit and execute the appropriate error handling routine. The PMCON2 register is a write-only register. Attempting to read the PMCON2 register will return all ‘0’s. To enable writes to the program memory, a specific pattern (the unlock sequence), must be written to the PMCON2 register. The required unlock sequence prevents inadvertent writes to the program memory write latches and Flash Program Memory. 10.2 Flash Program Memory Overview It is important to understand the Flash Program Memory structure for erase and programming operations. Flash Program Memory is arranged in rows. A row consists of a fixed number of 14-bit program memory words. A row is the minimum size that can be erased by user software. After a row has been erased, the user can reprogram all or a portion of this row. Data to be written into the program memory row is written to 14-bit wide data write latches. These write latches are not directly accessible to the user, but may be loaded via sequential writes to the PMDATH:PMDATL register pair. Note: If the user wants to modify only a portion of a previously programmed row, then the contents of the entire row must be read and saved in RAM prior to the erase. Then, new data and retained data can be written into the write latches to reprogram the row of Flash Program Memory. However, any unprogrammed locations can be written without first erasing the row. In this case, it is not necessary to save and rewrite the other previously programmed locations. See Table 10-1 for Erase Row size and the number of write latches for Flash Program Memory.  2011-2016 Microchip Technology Inc. PIC16LF1902/3 TABLE 10-1: Device PIC16(L)F1902 PIC16(L)F1903 10.2.1 FLASH MEMORY ORGANIZATION BY DEVICE Row Erase (words) Write Latches (words) 32 32 READING THE FLASH PROGRAM MEMORY FIGURE 10-1: FLASH PROGRAM MEMORY READ FLOWCHART Start Read Operation Select Program or Configuration Memory (CFGS) To read a program memory location, the user must: 1. 2. 3. Write the desired address to the PMADRH:PMADRL register pair. Clear the CFGS bit of the PMCON1 register. Then, set control bit RD of the PMCON1 register. Once the read control bit is set, the program memory Flash controller will use the second instruction cycle to read the data. This causes the second instruction immediately following the “BSF PMCON1,RD” instruction to be ignored. The data is available in the very next cycle, in the PMDATH:PMDATL register pair; therefore, it can be read as two bytes in the following instructions. PMDATH:PMDATL register pair will hold this value until another read or until it is written to by the user. Note: The two instructions following a program memory read are required to be NOPs. This prevents the user from executing a 2-cycle instruction on the next instruction after the RD bit is set. Select Word Address (PMADRH:PMADRL) Initiate Read Operation (RD = 1) Instruction Fetched ignored NOP execution forced Instruction Fetched ignored NOP execution forced Data read now in PMDATH:PMDATL End Read Operation  2011-2016 Microchip Technology Inc. DS40001455F-page 73 PIC16LF1902/3 FIGURE 10-2: FLASH PROGRAM MEMORY READ CYCLE EXECUTION Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 PC Flash ADDR Flash Data PC + 1 INSTR (PC) INSTR(PC - 1) executed here PC +3 PC+3 PMADRH,PMADRL INSTR (PC + 1) BSF PMCON1,RD executed here PMDATH,PMDATL INSTR(PC + 1) instruction ignored Forced NOP executed here PC + 4 INSTR (PC + 3) INSTR(PC + 2) instruction ignored Forced NOP executed here PC + 5 INSTR (PC + 4) INSTR(PC + 3) executed here INSTR(PC + 4) executed here RD bit PMDATH PMDATL Register EXAMPLE 10-1: FLASH PROGRAM MEMORY READ * This code block will read 1 word of program * memory at the memory address: PROG_ADDR_HI : PROG_ADDR_LO * data will be returned in the variables; * PROG_DATA_HI, PROG_DATA_LO BANKSEL MOVLW MOVWF MOVLW MOVWL PMADRL PROG_ADDR_LO PMADRL PROG_ADDR_HI PMADRH ; Select Bank for PMCON registers ; ; Store LSB of address ; ; Store MSB of address BCF BSF NOP NOP PMCON1,CFGS PMCON1,RD ; ; ; ; Do not select Configuration Space Initiate read Ignored (Figure 10-2) Ignored (Figure 10-2) MOVF MOVWF MOVF MOVWF PMDATL,W PROG_DATA_LO PMDATH,W PROG_DATA_HI ; ; ; ; Get LSB of word Store in user location Get MSB of word Store in user location DS40001455F-page 74  2011-2016 Microchip Technology Inc. PIC16LF1902/3 10.2.2 FLASH MEMORY UNLOCK SEQUENCE The unlock sequence is a mechanism that protects the Flash Program Memory from unintended self-write programming or erasing. The sequence must be executed and completed without interruption to successfully complete any of the following operations: • Row Erase • Load program memory write latches • Write of program memory write latches to program memory • Write of program memory write latches to User IDs The unlock sequence consists of the following steps: FIGURE 10-3: FLASH PROGRAM MEMORY UNLOCK SEQUENCE FLOWCHART Start Unlock Sequence Write 055h to PMCON2 Write 0AAh to PMCON2 1. Write 55h to PMCON2 2. Write AAh to PMCON2 3. Set the WR bit in PMCON1 Initiate Write or Erase Operation (WR = 1) 4. NOP instruction 5. NOP instruction Once the WR bit is set, the processor will always force two NOP instructions. When an Erase Row or Program Row operation is being performed, the processor will stall internal operations (typical 2 ms), until the operation is complete and then resume with the next instruction. When the operation is loading the program memory write latches, the processor will always force the two NOP instructions and continue uninterrupted with the next instruction. Instruction Fetched ignored NOP execution forced Instruction Fetched ignored NOP execution forced End Unlock Sequence Since the unlock sequence must not be interrupted, global interrupts should be disabled prior to the unlock sequence and re-enabled after the unlock sequence is completed.  2011-2016 Microchip Technology Inc. DS40001455F-page 75 PIC16LF1902/3 10.2.3 ERASING FLASH PROGRAM MEMORY While executing code, program memory can only be erased by rows. To erase a row: 1. 2. 3. 4. 5. Load the PMADRH:PMADRL register pair with any address within the row to be erased. Clear the CFGS bit of the PMCON1 register. Set the FREE and WREN bits of the PMCON1 register. Write 55h, then AAh, to PMCON2 (Flash programming unlock sequence). Set control bit WR of the PMCON1 register to begin the erase operation. See Example 10-2. After the “BSF PMCON1,WR” instruction, the processor requires two cycles to set up the erase operation. The user must place two NOP instructions after the WR bit is set. The processor will halt internal operations for the typical 2 ms erase time. This is not Sleep mode as the clocks and peripherals will continue to run. After the erase cycle, the processor will resume operation with the third instruction after the PMCON1 WRITE instruction. FIGURE 10-4: FLASH PROGRAM MEMORY ERASE FLOWCHART Start Erase Operation Disable Interrupts (GIE = 0) Select Program or Configuration Memory (CFGS) Select Row Address (PMADRH:PMADRL) Select Erase Operation (FREE = 1) Enable Write/Erase Operation (WREN = 1) Unlock Sequence Figure 10-3 (FIGURE x-x) CPU stalls while Erase operation completes (2ms typical) Disable Write/Erase Operation (WREN = 0) Re-enable Interrupts (GIE = 1) End Erase Operation DS40001455F-page 76  2011-2016 Microchip Technology Inc. PIC16LF1902/3 EXAMPLE 10-2: ERASING ONE ROW OF PROGRAM MEMORY Required Sequence ; This row erase routine assumes the following: ; 1. A valid address within the erase row is loaded in ADDRH:ADDRL ; 2. ADDRH and ADDRL are located in shared data memory 0x70 - 0x7F (common RAM) BCF BANKSEL MOVF MOVWF MOVF MOVWF BCF BSF BSF INTCON,GIE PMADRL ADDRL,W PMADRL ADDRH,W PMADRH PMCON1,CFGS PMCON1,FREE PMCON1,WREN MOVLW MOVWF MOVLW MOVWF BSF NOP NOP 55h PMCON2 0AAh PMCON2 PMCON1,WR BCF BSF PMCON1,WREN INTCON,GIE  2011-2016 Microchip Technology Inc. ; Disable ints so required sequences will execute properly ; Load lower 8 bits of erase address boundary ; Load upper 6 bits of erase address boundary ; Not configuration space ; Specify an erase operation ; Enable writes ; ; ; ; ; ; ; ; ; ; Start of required sequence to initiate erase Write 55h Write AAh Set WR bit to begin erase NOP instructions are forced as processor starts row erase of program memory. The processor stalls until the erase process is complete after erase processor continues with 3rd instruction ; Disable writes ; Enable interrupts DS40001455F-page 77 PIC16LF1902/3 10.2.4 WRITING TO FLASH PROGRAM MEMORY Program memory is programmed using the following steps: 1. 2. 3. 4. Load the address in PMADRH:PMADRL of the row to be programmed. Load each write latch with data. Initiate a programming operation. Repeat steps 1 through 3 until all data is written. The following steps should be completed to load the write latches and program a row of program memory. These steps are divided into two parts. First, each write latch is loaded with data from the PMDATH:PMDATL using the unlock sequence with LWLO = 1. When the last word to be loaded into the write latch is ready, the LWLO bit is cleared and the unlock sequence executed. This initiates the programming operation, writing all the latches into Flash Program Memory. Note: Before writing to program memory, the word(s) to be written must be erased or previously unwritten. Program memory can only be erased one row at a time. No automatic erase occurs upon the initiation of the write. Program memory can be written one or more words at a time. The maximum number of words written at one time is equal to the number of write latches. See Figure 10-5 (row writes to program memory with 32 write latches) for more details. The write latches are aligned to the Flash row address boundary defined by the upper ten bits of PMADRH:PMADRL, (PMADRH:PMADRL) with the lower five bits of PMADRL, (PMADRL) determining the write latch being loaded. Write operations do not cross these boundaries. At the completion of a program memory write operation, the data in the write latches is reset to contain 0x3FFF. The special unlock sequence is required to load a write latch with data or initiate a Flash programming operation. If the unlock sequence is interrupted, writing to the latches or program memory will not be initiated. 1. 2. 3. Set the WREN bit of the PMCON1 register. Clear the CFGS bit of the PMCON1 register. Set the LWLO bit of the PMCON1 register. When the LWLO bit of the PMCON1 register is ‘1’, the write sequence will only load the write latches and will not initiate the write to Flash Program Memory. 4. Load the PMADRH:PMADRL register pair with the address of the location to be written. 5. Load the PMDATH:PMDATL register pair with the program memory data to be written. 6. Execute the unlock sequence (Section 10.2.2 “Flash Memory Unlock Sequence”). The write latch is now loaded. 7. Increment the PMADRH:PMADRL register pair to point to the next location. 8. Repeat steps 5 through 7 until all but the last write latch has been loaded. 9. Clear the LWLO bit of the PMCON1 register. When the LWLO bit of the PMCON1 register is ‘0’, the write sequence will initiate the write to Flash Program Memory. 10. Load the PMDATH:PMDATL register pair with the program memory data to be written. 11. Execute the unlock sequence (Section 10.2.2 “Flash Memory Unlock Sequence”). The entire program memory latch content is now written to Flash Program Memory. Note: The program memory write latches are reset to the blank state (0x3FFF) at the completion of every write or erase operation. As a result, it is not necessary to load all the program memory write latches. Unloaded latches will remain in the blank state. An example of the complete write sequence is shown in Example 10-3. The initial address is loaded into the PMADRH:PMADRL register pair; the data is loaded using indirect addressing. DS40001455F-page 78  2011-2016 Microchip Technology Inc. 7 BLOCK WRITES TO FLASH PROGRAM MEMORY WITH 32 WRITE LATCHES 6 0 7 5 4 PMADRH - r9 r8 r7 r6 r5 7 0 PMADRL r4 r3 r2 r1 r0 c4 c3 c2 c1 c0 5 - 0 7 PMDATH 6 0 PMDATL 8 14 10 Program Memory Write Latches 5 14 Write Latch #0 00h PMADRL 14 CFGS = 0  2011-2016 Microchip Technology Inc. PMADRH :PMADRL Row Address Decode 14 14 Write Latch #1 01h 14 Write Latch #30 Write Latch #31 1Eh 1Fh 14 14 14 Row Addr Addr Addr Addr 000h 0000h 0001h 001Eh 001Fh 001h 0020h 0021h 003Eh 003Fh 002h 0040h 0041h 005Eh 005Fh 3FEh 7FC0h 7FC1h 7FDEh 7FDFh 3FFh 7FE0h 7FE1h 7FFEh 7FFFh Flash Program Memory 400h CFGS = 1 8000h - 8003h 8004h - 8005h 8006h 8007h – 8008h 8009h - 801Fh USER ID 0 - 3 reserved DEVICEID REVID Configuration Words reserved Configuration Memory PIC16LF1902/3 DS40001455F-page 79 FIGURE 10-5: PIC16LF1902/3 FIGURE 10-6: FLASH PROGRAM MEMORY WRITE FLOWCHART Start Write Operation Determine number of words to be written into Program or Configuration Memory. The number of words cannot exceed the number of words per row. (word_cnt) Disable Interrupts (GIE = 0) Select Program or Config. Memory (CFGS) Select Row Address (PMADRH:PMADRL) Enable Write/Erase Operation (WREN = 1) Load the value to write (PMDATH:PMDATL) Update the word counter (word_cnt--) Last word to write ? Yes No Unlock Sequence (Figure10-3 x-x) Figure Select Write Operation (FREE = 0) No delay when writing to Program Memory Latches Load Write Latches Only (LWLO = 1) Increment Address (PMADRH:PMADRL++) Write Latches to Flash (LWLO = 0) Unlock Sequence (Figure10-3 x-x) Figure CPU stalls while Write operation completes (2 ms typical) Disable Write/Erase Operation (WREN = 0) Re-enable Interrupts (GIE = 1) End Erase Operation DS40001455F-page 80  2011-2016 Microchip Technology Inc. PIC16LF1902/3 EXAMPLE 10-3: ; ; ; ; ; ; ; WRITING TO FLASH PROGRAM MEMORY This write routine assumes the following: 1. 64 bytes of data are loaded, starting at the address in DATA_ADDR 2. Each word of data to be written is made up of two adjacent bytes in DATA_ADDR, stored in little endian format 3. A valid starting address (the least significant bits = 00000) is loaded in ADDRH:ADDRL 4. ADDRH and ADDRL are located in shared data memory 0x70 - 0x7F (common RAM) BCF BANKSEL MOVF MOVWF MOVF MOVWF MOVLW MOVWF MOVLW MOVWF BCF BSF BSF INTCON,GIE PMADRH ADDRH,W PMADRH ADDRL,W PMADRL LOW DATA_ADDR FSR0L HIGH DATA_ADDR FSR0H PMCON1,CFGS PMCON1,WREN PMCON1,LWLO ; ; ; ; ; ; ; ; ; ; ; ; ; Disable ints so required sequences will execute properly Bank 3 Load initial address MOVIW MOVWF MOVIW MOVWF FSR0++ PMDATL FSR0++ PMDATH ; Load first data byte into lower ; ; Load second data byte into upper ; MOVF XORLW ANDLW BTFSC GOTO PMADRL,W 0x1F 0x1F STATUS,Z START_WRITE ; Check if lower bits of address are '00000' ; Check if we're on the last of 32 addresses ; ; Exit if last of 32 words, ; MOVLW MOVWF MOVLW MOVWF BSF NOP 55h PMCON2 0AAh PMCON2 PMCON1,WR ; ; ; ; ; ; ; ; PMADRL,F LOOP ; Still loading latches Increment address ; Write next latches PMCON1,LWLO ; No more loading latches - Actually start Flash program ; memory write 55h PMCON2 0AAh PMCON2 PMCON1,WR ; ; ; ; ; ; ; ; ; ; ; ; ; Load initial data address Load initial data address Not configuration space Enable writes Only Load Write Latches Required Sequence LOOP NOP INCF GOTO Required Sequence START_WRITE BCF MOVLW MOVWF MOVLW MOVWF BSF NOP NOP BCF BSF PMCON1,WREN INTCON,GIE  2011-2016 Microchip Technology Inc. Start of required write sequence: Write 55h Write AAh Set WR bit to begin write NOP instructions are forced as processor loads program memory write latches Start of required write sequence: Write 55h Write AAh Set WR bit to begin write NOP instructions are forced as processor writes all the program memory write latches simultaneously to program memory. After NOPs, the processor stalls until the self-write process in complete after write processor continues with 3rd instruction Disable writes Enable interrupts DS40001455F-page 81 PIC16LF1902/3 10.3 Modifying Flash Program Memory When modifying existing data in a program memory row, and data within that row must be preserved, it must first be read and saved in a RAM image. Program memory is modified using the following steps: 1. 2. 3. 4. 5. 6. 7. Load the starting address of the row to be modified. Read the existing data from the row into a RAM image. Modify the RAM image to contain the new data to be written into program memory. Load the starting address of the row to be rewritten. Erase the program memory row. Load the write latches with data from the RAM image. Initiate a programming operation. FIGURE 10-7: FLASH PROGRAM MEMORY MODIFY FLOWCHART Start Modify Operation Read Operation (Figure10-2 x.x) Figure An image of the entire row read must be stored in RAM Modify Image The words to be modified are changed in the RAM image Erase Operation (Figure10-4 x.x) Figure Write Operation use RAM image (Figure10-5 x.x) Figure End Modify Operation DS40001455F-page 82  2011-2016 Microchip Technology Inc. PIC16LF1902/3 10.4 User ID, Device ID and Configuration Word Access Instead of accessing program memory, the User ID’s, Device ID/Revision ID and Configuration Words can be accessed when CFGS = 1 in the PMCON1 register. This is the region that would be pointed to by PC = 1, but not all addresses are accessible. Different access may exist for reads and writes. Refer to Table 10-2. When read access is initiated on an address outside the parameters listed in Table 10-2, the PMDATH:PMDATL register pair is cleared, reading back ‘0’s. TABLE 10-2: USER ID, DEVICE ID AND CONFIGURATION WORD ACCESS (CFGS = 1) Address Function Read Access Write Access 8000h-8003h 8006h 8007h-8008h User IDs Device ID/Revision ID Configuration Words 1 and 2 Yes Yes Yes Yes No No EXAMPLE 10-4: CONFIGURATION WORD AND DEVICE ID ACCESS * This code block will read 1 word of program memory at the memory address: * PROG_ADDR_LO (must be 00h-08h) data will be returned in the variables; * PROG_DATA_HI, PROG_DATA_LO BANKSEL MOVLW MOVWF CLRF PMADRL PROG_ADDR_LO PMADRL PMADRH ; Select correct Bank ; ; Store LSB of address ; Clear MSB of address BSF BCF BSF NOP NOP BSF PMCON1,CFGS INTCON,GIE PMCON1,RD INTCON,GIE ; ; ; ; ; ; Select Configuration Space Disable interrupts Initiate read Executed (See Figure 10-2) Ignored (See Figure 10-2) Restore interrupts MOVF MOVWF MOVF MOVWF PMDATL,W PROG_DATA_LO PMDATH,W PROG_DATA_HI ; ; ; ; Get LSB of word Store in user location Get MSB of word Store in user location  2011-2016 Microchip Technology Inc. DS40001455F-page 83 PIC16LF1902/3 10.5 Write Verify It is considered good programming practice to verify that program memory writes agree with the intended value. Since program memory is stored as a full page then the stored program memory contents are compared with the intended data stored in RAM after the last write is complete. FIGURE 10-8: FLASH PROGRAM MEMORY VERIFY FLOWCHART Start Verify Operation This routine assumes that the last row of data written was from an image saved in RAM. This image will be used to verify the data currently stored in Flash Program Memory. Read Operation (Figure x.x) Figure 10-2 PMDAT = RAM image ? Yes No No Fail Verify Operation Last Word ? Yes End Verify Operation DS40001455F-page 84  2011-2016 Microchip Technology Inc. PIC16LF1902/3 10.6 Flash Program Memory Control Registers REGISTER 10-1: R/W-x/u PMDATL: PROGRAM MEMORY DATA LOW BYTE REGISTER R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u PMDAT bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-0 PMDAT: Read/write value for Least Significant bits of program memory REGISTER 10-2: PMDATH: PROGRAM MEMORY DATA HIGH BYTE REGISTER U-0 U-0 — — R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u PMDAT bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-6 Unimplemented: Read as ‘0’ bit 5-0 PMDAT: Read/write value for Most Significant bits of program memory REGISTER 10-3: R/W-0/0 PMADRL: PROGRAM MEMORY ADDRESS LOW BYTE REGISTER R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 PMADR bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-0 PMADR: Specifies the Least Significant bits for program memory address REGISTER 10-4: U-1 PMADRH: PROGRAM MEMORY ADDRESS HIGH BYTE REGISTER R/W-0/0 R/W-0/0 — R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 PMADR bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7 Unimplemented: Read as ‘1’ bit 6-0 PMADR: Specifies the Most Significant bits for program memory address  2011-2016 Microchip Technology Inc. DS40001455F-page 85 PIC16LF1902/3 REGISTER 10-5: PMCON1: PROGRAM MEMORY CONTROL 1 REGISTER U-1(1) R/W-0/0 R/W-0/0 R/W/HC-0/0 R/W/HC-x/q(2) R/W-0/0 R/S/HC-0/0 R/S/HC-0/0 — CFGS LWLO FREE WRERR WREN WR RD bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ S = Bit can only be set x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared HC = Bit is cleared by hardware bit 7 Unimplemented: Read as ‘1’ bit 6 CFGS: Configuration Select bit 1 = Access configuration, User ID and Device ID registers 0 = Access Flash Program Memory bit 5 LWLO: Load Write Latches Only bit(3) 1 = Only the addressed program memory write latch is loaded/updated on the next WR command 0 = The addressed program memory write latch is loaded/updated and a write of all program memory write latches will be initiated on the next WR command bit 4 FREE: Program Flash Erase Enable bit 1 = Performs an erase operation on the next WR command (hardware cleared upon completion) 0 = Performs an write operation on the next WR command bit 3 WRERR: Program/Erase Error Flag bit 1 = Condition indicates an improper program or erase sequence attempt or termination (bit is set automatically on any set attempt (write ‘1’) of the WR bit). 0 = The program or erase operation completed normally. bit 2 WREN: Program/Erase Enable bit 1 = Allows program/erase cycles 0 = Inhibits programming/erasing of program Flash bit 1 WR: Write Control bit 1 = Initiates a program Flash program/erase operation. The operation is self-timed and the bit is cleared by hardware once operation is complete. The WR bit can only be set (not cleared) in software. 0 = Program/erase operation to the Flash is complete and inactive. bit 0 RD: Read Control bit 1 = Initiates a program Flash read. Read takes one cycle. RD is cleared in hardware. The RD bit can only be set (not cleared) in software. 0 = Does not initiate a program Flash read. Note 1: 2: 3: Unimplemented bit, read as ‘1’. The WRERR bit is automatically set by hardware when a program memory write or erase operation is started (WR = 1). The LWLO bit is ignored during a program memory erase operation (FREE = 1). DS40001455F-page 86  2011-2016 Microchip Technology Inc. PIC16LF1902/3 REGISTER 10-6: W-0/0 PMCON2: PROGRAM MEMORY CONTROL 2 REGISTER W-0/0 W-0/0 W-0/0 W-0/0 W-0/0 W-0/0 W-0/0 Program Memory Control Register 2 bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ S = Bit can only be set x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-0 Flash Memory Unlock Pattern bits To unlock writes, a 55h must be written first, followed by an AAh, before setting the WR bit of the PMCON1 register. The value written to this register is used to unlock the writes. There are specific timing requirements on these writes. TABLE 10-3: Name PMCON1 SUMMARY OF REGISTERS ASSOCIATED WITH FLASH PROGRAM MEMORY Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Register on Page —(1) CFGS LWLO FREE WRERR WREN WR RD 86 PMCON2 Program Memory Control Register 2 PMADRL PMADRL —(1) PMADRH INTCON — GIE PEIE CONFIG2 Legend: 85 PMDATH TMR0IE INTE IOCIE 85 TMR0IF INTF IOCIF 60 — = unimplemented location, read as ‘0’. Shaded cells are not used by Flash Program Memory module. Unimplemented, read as ‘1’. TABLE 10-4: CONFIG1 85 PMDATL — PMDATH Name 85 PMADRH PMDATL Legend: Note 1: 87 SUMMARY OF CONFIGURATION WORD WITH FLASH PROGRAM MEMORY Bits Bit -/7 Bit -/6 Bit 13/5 Bit 12/4 Bit 11/3 13:8 — — — — CLKOUTEN 7:0 CP MCLRE PWRTE 13:8 — — LVP DEBUG LPBOR BORV 7:0 — — — — — — WDTE Bit 10/2 Bit 9/1 Bit 8/0 — BOREN — FOSC STVREN — WRT Register on Page 34 35 — = unimplemented location, read as ‘0’. Shaded cells are not used by clock sources.  2011-2016 Microchip Technology Inc. DS40001455F-page 87 PIC16LF1902/3 11.0 I/O PORTS FIGURE 11-1: GENERIC I/O PORT OPERATION In general, when a peripheral is enabled on a port pin, that pin cannot be used as a general purpose output. However, the pin can still be read. Each port has three standard registers for its operation. These registers are: • TRISx registers (data direction) • PORTx registers (reads the levels on the pins of the device) • LATx registers (output latch) Some ports may have one or more of the following additional registers. These registers are: D Write LATx Write PORTx Q CK VDD Data Register Data Bus Read PORTx To peripherals ANSELx Device PORTA PORTB PORTC PORTE PORT AVAILABILITY PER DEVICE PIC16LF1902/3 ● ● ● ● The Data Latch (LATA register) is useful for read-modify-write operations on the value that the I/O pins are driving. A write operation to the LATA register has the same effect as a write to the corresponding PORTA register. A read of the LATA register reads of the values held in the I/O PORT latches, while a read of the PORTA register reads the actual I/O pin value. Ports that support analog inputs have an associated ANSELx register. When an ANSEL bit is set, the digital input buffer associated with that bit is disabled. Disabling the input buffer prevents analog signal levels on the pin between a logic high and low from causing excessive current in the logic input circuitry. A simplified model of a generic I/O port, without the interfaces to other peripherals, is shown in Figure 11-1. DS40001455F-page 88 TRISx I/O pin • ANSELx (analog select) • WPUx (weak pull-up) TABLE 11-1: Read LATx EXAMPLE 11-1: ; ; ; ; VSS INITIALIZING PORTA This code example illustrates initializing the PORTA register. The other ports are initialized in the same manner. BANKSEL CLRF BANKSEL CLRF BANKSEL CLRF BANKSEL MOVLW MOVWF PORTA PORTA LATA LATA ANSELA ANSELA TRISA B'00111000' TRISA ; ;Init PORTA ;Data Latch ; ; ;digital I/O ; ;Set RA as inputs ;and set RA as ;outputs  2011-2016 Microchip Technology Inc. PIC16LF1902/3 11.1 PORTA Registers PORTA is an 8-bit wide, bidirectional port. The corresponding data direction register is TRISA (Register 11-2). Setting a TRISA bit (= 1) will make the corresponding PORTA pin an input (i.e., disable the output driver). Clearing a TRISA bit (= 0) will make the corresponding PORTA pin an output (i.e., enables output driver and puts the contents of the output latch on the selected pin). The exception is RA3, which is input only and its TRIS bit will always read as ‘1’. Example 11-1 shows how to initialize PORTA. Reading the PORTA register (Register 11-1) reads the status of the pins, whereas writing to it will write to the PORT latch. All write operations are read-modify-write operations. Therefore, a write to a port implies that the port pins are read, this value is modified and then written to the PORT data latch (LATA). 11.1.2 PORTA FUNCTIONS AND OUTPUT PRIORITIES Each PORTA pin is multiplexed with other functions. The pins, their combined functions and their output priorities are shown in Table 11-2. When multiple outputs are enabled, the actual pin control goes to the peripheral with the highest priority. Analog input functions, such as ADC, comparator and CapSense inputs, are not shown in the priority lists. These inputs are active when the I/O pin is set for Analog mode using the ANSELx registers. Digital output functions may control the pin when it is in Analog mode with the priority shown in Table 11-2. TABLE 11-2: Pin Name PORTA OUTPUT PRIORITY Function Priority(1) The TRISA register (Register 11-2) controls the PORTA pin output drivers, even when they are being used as analog inputs. The user should ensure the bits in the TRISA register are maintained set when using them as analog inputs. I/O pins configured as analog input always read ‘0’. RA0 SEG12 (LCD) AN0 RA0 RA1 SEG7 AN1 RA1 11.1.1 RA2 COM2 AN2 RA2 RA3 VREF+ COM3 SEG15 AN3 RA3 RA4 SEG4 T0CKI RA4 RA5 SEG6 AN5 RA5 RA6 CLKOUT SEG1 RA6 RA7 CLKIN SEG2 RA7 ANSELA REGISTER The ANSELA register (Register 11-4) is used to configure the Input mode of an I/O pin to analog. Setting the appropriate ANSELA bit high will cause all digital reads on the pin to be read as ‘0’ and allow analog functions on the pin to operate correctly. The state of the ANSELA bits has no effect on digital output functions. A pin with TRIS clear and ANSEL set will still operate as a digital output, but the Input mode will be analog. This can cause unexpected behavior when executing read-modify-write instructions on the affected port. Note: The ANSELA bits default to the Analog mode after Reset. To use any pins as digital general purpose or peripheral inputs, the corresponding ANSEL bits must be initialized to ‘0’ by user software. Note 1:  2011-2016 Microchip Technology Inc. Priority listed from highest to lowest. DS40001455F-page 89 PIC16LF1902/3 REGISTER 11-1: PORTA: PORTA REGISTER R/W-x/x R/W-x/x R/W-x/x R/W-x/x R-x/x R/W-x/x R/W-x/x R/W-x/x RA7 RA6 RA5 RA4 RA3 RA2 RA1 RA0 bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared RA: PORTA I/O Value bits(1) 1 = Port pin is > VIH 0 = Port pin is < VIL bit 7-0 Note 1: Writes to PORTA are actually written to corresponding LATA register. Reads from PORTA register is return of actual I/O pin values. REGISTER 11-2: TRISA: PORTA TRI-STATE REGISTER R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1 R-1/1 R/W-1/1 R/W-1/1 R/W-1/1 TRISA7 TRISA6 TRISA5 TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-4 TRISA: PORTA Tri-State Control bits 1 = PORTA pin configured as an input (tri-stated) 0 = PORTA pin configured as an output bit 3 TRISA3: RA3 Port Tri-State Control bit This bit is always ‘1’ as RA3 is an input only bit 2-0 TRISA: PORTA Tri-State Control bits 1 = PORTA pin configured as an input (tri-stated) 0 = PORTA pin configured as an output REGISTER 11-3: LATA: PORTA DATA LATCH REGISTER R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u LATA7 LATA6 LATA5 LATA4 LATA3 LATA2 LATA1 LATA0 bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-4 Note 1: LATA: PORTA Output Latch Value bits(1) Writes to PORTA are actually written to corresponding LATA register. Reads from PORTA register is return of actual I/O pin values. DS40001455F-page 90  2011-2016 Microchip Technology Inc. PIC16LF1902/3 REGISTER 11-4: ANSELA: PORTA ANALOG SELECT REGISTER U-0 U-0 R/W-1/1 U-0 R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1 — — ANSA5 — ANSA3 ANSA2 ANSA1 ANSA0 bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-6 Unimplemented: Read as ‘0’ bit 5 ANSA5: Analog Select between Analog or Digital Function on pins RA5, respectively 0 = Digital I/O. Pin is assigned to port or digital special function. 1 = Analog input. Pin is assigned as analog input(1). Digital input buffer disabled. bit 4 Unimplemented: Read as ‘0’ bit 3-0 ANSA: Analog Select between Analog or Digital Function on pins RA, respectively 0 = Digital I/O. Pin is assigned to port or digital special function. 1 = Analog input. Pin is assigned as analog input(1). Digital input buffer disabled. Note 1: When setting a pin to an analog input, the corresponding TRIS bit must be set to Input mode in order to allow external control of the voltage on the pin. TABLE 11-3: Name ANSELA LATA OPTION_REG SUMMARY OF REGISTERS ASSOCIATED WITH PORTA Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Register on Page — — ANSA5 — ANSA3 ANSA2 ANSA1 ANSA0 91 LATA2 LATA1 LATA0 LATA7 LATA6 LATA5 LATA4 LATA3 WPUEN INTEDG TMR0CS TMR0SE PSA 90 PS 121 PORTA RA7 RA6 RA5 RA4 RA3 RA2 RA1 RA0 90 TRISA TRISA7 TRISA6 TRISA5 TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 90 Legend: x = unknown, u = unchanged, – = unimplemented locations read as ‘0’. Shaded cells are not used by PORTA. TABLE 11-4: Name CONFIG1 Legend: Bits SUMMARY OF CONFIGURATION WORD WITH PORTA Bit -/7 Bit -/6 Bit 13/5 Bit 12/4 Bit 11/3 — CLKOUTEN 13:8 — — — 7:0 CP MCLRE PWRTE Bit 10/2 WDTE Bit 9/1 BOREN — Bit 8/0 — FOSC Register on Page 34 — = unimplemented location, read as ‘0’. Shaded cells are not used by PORTA.  2011-2016 Microchip Technology Inc. DS40001455F-page 91 PIC16LF1902/3 11.2 PORTB Registers PORTB is an 8-bit wide, bidirectional port. The corresponding data direction register is TRISB (Register 11-6). Setting a TRISB bit (= 1) will make the corresponding PORTB pin an input (i.e., put the corresponding output driver in a High-Impedance mode). Clearing a TRISB bit (= 0) will make the corresponding PORTB pin an output (i.e., enable the output driver and put the contents of the output latch on the selected pin). Example 11-1 shows how to initialize an I/O port. Reading the PORTB register (Register 11-5) reads the status of the pins, whereas writing to it will write to the PORT latch. All write operations are read-modify-write operations. Therefore, a write to a port implies that the port pins are read, this value is modified and then written to the PORT data latch (LATB). 11.2.2 Each PORTB pin is multiplexed with other functions. The pins, their combined functions and their output priorities are shown in Table 11-5. When multiple outputs are enabled, the actual pin control goes to the peripheral with the highest priority. Analog input and some digital input functions are not included in the list below. These input functions can remain active when the pin is configured as an output. Certain digital input functions override other port functions and are included in Table 11-5. TABLE 11-5: Pin Name The TRISB register (Register 11-6) controls the PORTB pin output drivers, even when they are being used as analog inputs. The user should ensure the bits in the TRISB register are maintained set when using them as analog inputs. I/O pins configured as analog input always read ‘0’. 11.2.1 The state of the ANSELB bits has no effect on digital output functions. A pin with TRIS clear and ANSELB set will still operate as a digital output, but the Input mode will be analog. This can cause unexpected behavior when executing read-modify-write instructions on the affected port. The ANSELB bits default to the Analog mode after Reset. To use any pins as digital general purpose or peripheral inputs, the corresponding ANSEL bits must be initialized to ‘0’ by user software. Note 1: DS40001455F-page 92 PORTB OUTPUT PRIORITY Function Priority(1) RB0 SEG0 AN12 INT IOC RB0 RB1 SEG24 AN10 VLCD1 IOC RB1 RB2 SEG25 AN8 VLCD2 IOC RB2 RB3 SEG26 AN9 VLCD3 IOC RB3 RB4 COM0 AN11 IOC RB4 RB5 COM1 AN13 IOC RB5 RB6 SEG14 IOC RB6 RB7 SEG13 IOC RB7 ANSELB REGISTER The ANSELB register (Register 11-8) is used to configure the Input mode of an I/O pin to analog. Setting the appropriate ANSELB bit high will cause all digital reads on the pin to be read as ‘0’ and allow analog functions on the pin to operate correctly. Note: PORTB FUNCTIONS AND OUTPUT PRIORITIES Priority listed from highest to lowest.  2011-2016 Microchip Technology Inc. PIC16LF1902/3 REGISTER 11-5: PORTB: PORTB REGISTER R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u RB7 RB6 RB5 RB4 RB3 RB2 RB1 RB0 bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared RB: PORTB General Purpose I/O Pin bits(1) 1 = Port pin is > VIH 0 = Port pin is < VIL bit 7-0 Note 1: Writes to PORTB are actually written to corresponding LATB register. Reads from PORTB register is return of actual I/O pin values. REGISTER 11-6: TRISB: PORTB TRI-STATE REGISTER R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1 TRISB7 TRISB6 TRISB5 TRISB4 TRISB3 TRISB2 TRISB1 TRISB0 bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-0 TRISB: PORTB Tri-State Control bits 1 = PORTB pin configured as an input (tri-stated) 0 = PORTB pin configured as an output REGISTER 11-7: LATB: PORTB DATA LATCH REGISTER R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u LATB7 LATB6 LATB5 LATB4 LATB3 LATB2 LATB1 LATB0 bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-0 Note 1: LATB: PORTB Output Latch Value bits(1) Writes to PORTB are actually written to corresponding LATB register. Reads from PORTB register is return of actual I/O pin values.  2011-2016 Microchip Technology Inc. DS40001455F-page 93 PIC16LF1902/3 REGISTER 11-8: ANSELB: PORTB ANALOG SELECT REGISTER U-0 U-0 R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1 — — ANSB5 ANSB4 ANSB3 ANSB2 ANSB1 ANSB0 bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-6 Unimplemented: Read as ‘0’ bit 5-0 ANSB: Analog Select between Analog or Digital Function on pins RB, respectively 0 = Digital I/O. Pin is assigned to port or digital special function. 1 = Analog input. Pin is assigned as analog input(1). Digital input buffer disabled. Note 1: When setting a pin to an analog input, the corresponding TRIS bit must be set to Input mode in order to allow external control of the voltage on the pin. REGISTER 11-9: WPUB: WEAK PULL-UP PORTB REGISTER R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1 WPUB7 WPUB6 WPUB5 WPUB4 WPUB3 WPUB2 WPUB1 WPUB0 bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared WPUB: Weak Pull-up Register bits 1 = Pull-up enabled 0 = Pull-up disabled bit 7-0 Note 1: 2: Global WPUEN bit of the OPTION_REG register must be cleared for individual pull-ups to be enabled. The weak pull-up device is automatically disabled if the pin is in configured as an output. TABLE 11-6: Name ANSELB LATB PORTB SUMMARY OF REGISTERS ASSOCIATED WITH PORTB Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Register on Page — — ANSB5 ANSB4 ANSB3 ANSB2 ANSB1 ANSB0 94 LATB7 LATB6 LATB5 LATB4 LATB3 LATB2 LATB1 LATB0 93 RB7 RB6 RB5 RB4 RB3 RB2 RB1 RB0 93 TRISB TRISB7 TRISB6 TRISB5 TRISB4 TRISB3 TRISB2 TRISB1 TRISB0 93 WPUB WPUB7 WPUB6 WPUB5 WPUB4 WPUB3 WPUB2 WPUB1 WPUB0 94 Legend: x = unknown, u = unchanged, - = unimplemented locations read as ‘0’. Shaded cells are not used by PORTB. DS40001455F-page 94  2011-2016 Microchip Technology Inc. PIC16LF1902/3 11.3 PORTC Registers PORTC is an 8-bit wide bidirectional port. The corresponding data direction register is TRISC (Register 11-6). Setting a TRISC bit (= 1) will make the corresponding PORTC pin an input (i.e., put the corresponding output driver in a High-Impedance mode). Clearing a TRISC bit (= 0) will make the corresponding PORTC pin an output (i.e., enable the output driver and put the contents of the output latch on the selected pin). Example 11-1 shows how to initialize an I/O port. Reading the PORTC register (Register 11-5) reads the status of the pins, whereas writing to it will write to the PORT latch. All write operations are read-modify-write operations. Therefore, a write to a port implies that the port pins are read, this value is modified and then written to the PORT data latch (LATC). The TRISC register (Register 11-6) controls the PORTC pin output drivers, even when they are being used as analog inputs. The user should ensure the bits in the TRISC register are maintained set when using them as analog inputs. I/O pins configured as analog input always read ‘0’. 11.3.1 PORTC FUNCTIONS AND OUTPUT PRIORITIES Each PORTC pin is multiplexed with other functions. The pins, their combined functions and their output priorities are shown in Table 11-7. When multiple outputs are enabled, the actual pin control goes to the peripheral with the highest priority. Analog input and some digital input functions are not included in the list below. These input functions can remain active when the pin is configured as an output. Certain digital input functions override other port functions and are included in Table 11-7. TABLE 11-7: Pin Name Function Priority(1) RC0 SOSCO (T1OSCO) T1CKI RC0 RC1 SOSC1 (T1OSCI) RC1 RC2 SEG2 RC2 RC3 SEG6 RC3 RC4 SEG11 T1G RC4 RC5 SEG10 RC5 RC6 SEG9 RC6 RC7 SEG8 RC7 Note 1:  2011-2016 Microchip Technology Inc. PORTC OUTPUT PRIORITY Priority listed from highest to lowest. DS40001455F-page 95 PIC16LF1902/3 REGISTER 11-10: PORTC: PORTC REGISTER R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u RC7 RC6 RC5 RC4 RC3 RC2 RC1 RC0 bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared RC: PORTC General Purpose I/O Pin bits(1) 1 = Port pin is > VIH 0 = Port pin is < VIL bit 7-0 Note 1: Writes to PORTC are actually written to corresponding LATC register. Reads from PORTC register is return of actual I/O pin values. REGISTER 11-11: TRISC: PORTC TRI-STATE REGISTER R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1 TRISC7 TRISC6 TRISC5 TRISC4 TRISC3 TRISC2 TRISC1 TRISC0 bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared TRISC: PORTC Tri-State Control bits(1) 1 = PORTC pin configured as an input (tri-stated) 0 = PORTC pin configured as an output bit 7-0 REGISTER 11-12: LATC: PORTC DATA LATCH REGISTER R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u LATC7 LATC6 LATC5 LATC4 LATC3 LATC2 LATC1 LATC0 bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-0 Note 1: LATC: PORTC Output Latch Value bits(1) Writes to PORTC are actually written to corresponding LATC register. Reads from PORTC register is return of actual I/O pin values. DS40001455F-page 96  2011-2016 Microchip Technology Inc. PIC16LF1902/3 TABLE 11-8: Name LATC SUMMARY OF REGISTERS ASSOCIATED WITH PORTC Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Register on Page LATC7 LATC6 LATC5 LATC4 LATC3 LATC2 LATC1 LATC0 93 PORTC RC7 RC6 RC5 RC4 RC3 RC2 RC1 RC0 93 TRISC TRISC7 TRISC6 TRISC5 TRISC4 TRISC3 TRISC2 TRISC1 TRISC0 93 Legend: x = unknown, u = unchanged, - = unimplemented locations read as ‘0’. Shaded cells are not used by PORTC.  2011-2016 Microchip Technology Inc. DS40001455F-page 97 PIC16LF1902/3 11.4 11.4.1 PORTE Registers RE3 is input only, and also functions as MCLR. The MCLR feature can be disabled via a configuration fuse. RE3 also supplies the programming voltage. The TRIS bit for RE3 (TRISE3) always reads ‘1’. PORTE FUNCTIONS AND OUTPUT PRIORITIES No output priorities, RE3 is an input only pin. REGISTER 11-13: PORTE: PORTE REGISTER U-0 U-0 U-0 U-0 R-x/u U-0 U-0 U-0 — — — — RE3 — — — bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-4 Unimplemented: Read as ‘0’ bit 3 RE3: PORTE Input Pin bit 1 = Port pin is > VIH 0 = Port pin is < VIL bit 2-0 Unimplemented: Read as ‘0’ REGISTER 11-14: TRISE: PORTE TRI-STATE REGISTER U-0 U-0 U-0 U-0 U-1(1) U-0 U-0 U-0 — — — — — — — — bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-4 Unimplemented: Read as ‘0’ bit 3 Unimplemented: Read as ‘1’ bit 2-0 Unimplemented: Read as ‘0’ Note 1: Unimplemented, read as ‘1’. DS40001455F-page 98  2011-2016 Microchip Technology Inc. PIC16LF1902/3 REGISTER 11-15: WPUE: WEAK PULL-UP PORTE REGISTER U-0 U-0 U-0 U-0 R/W-1/1 U-0 U-0 U-0 — — — — WPUE3 — — — bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-4 Unimplemented: Read as ‘0’ bit 3 WPUE: Weak Pull-up Register bit 1 = Pull-up enabled 0 = Pull-up disabled bit 2-0 Unimplemented: Read as ‘0’ Note 1: 2: Global WPUEN bit of the OPTION_REG register must be cleared for individual pull-ups to be enabled. The weak pull-up device is automatically disabled if the pin is in configured as an output. TABLE 11-9: Name SUMMARY OF REGISTERS ASSOCIATED WITH PORTE Bit 7 ADCON0 — PORTE — Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 CHS — — Bit 1 Bit 0 Register on Page GO/DONE ADON 112 — RE3 — — — 98 — — — 98 — — — 99 TRISE — — — — —(1) WPUE — — — — WPUE3 Legend: x = unknown, u = unchanged, – = unimplemented locations read as ‘0’. Shaded cells are not used by PORTE. Note 1: Unimplemented, read as ‘1’.  2011-2016 Microchip Technology Inc. DS40001455F-page 99 PIC16LF1902/3 12.0 INTERRUPT-ON-CHANGE The PORTB pins can be configured to operate as Interrupt-on-Change (IOC) pins. An interrupt can be generated by detecting a signal that has either a rising edge or a falling edge. Any individual PORTB pin, or combination of PORTB pins, can be configured to generate an interrupt. The interrupt-on-change module has the following features: • • • • Interrupt-on-Change enable (Master Switch) Individual pin configuration Rising and falling edge detection Individual pin interrupt flags Figure 12-1 is a block diagram of the IOC module. 12.1 Enabling the Module To allow individual PORTB pins to generate an interrupt, the IOCIE bit of the INTCON register must be set. If the IOCIE bit is disabled, the edge detection on the pin will still occur, but an interrupt will not be generated. 12.3 Interrupt Flags The IOCBFx bits located in the IOCBF register are status flags that correspond to the interrupt-on-change pins of PORTB. If an expected edge is detected on an appropriately enabled pin, then the status flag for that pin will be set, and an interrupt will be generated if the IOCIE bit is set. The IOCIF bit of the INTCON register reflects the status of all IOCBFx bits. 12.4 Clearing Interrupt Flags The individual status flags, (IOCBFx bits), can be cleared by resetting them to zero. If another edge is detected during this clearing operation, the associated status flag will be set at the end of the sequence, regardless of the value actually being written. In order to ensure that no detected edge is lost while clearing flags, only AND operations masking out known changed bits should be performed. The following sequence is an example of what should be performed. EXAMPLE 12-1: 12.2 Individual Pin Configuration For each PORTB pin, a rising edge detector and a falling edge detector are present. To enable a pin to detect a rising edge, the associated IOCBPx bit of the IOCBP register is set. To enable a pin to detect a falling edge, the associated IOCBNx bit of the IOCBN register is set. A pin can be configured to detect rising and falling edges simultaneously by setting both the IOCBPx bit and the IOCBNx bit of the IOCBP and IOCBN registers, respectively. FIGURE 12-1: MOVLW XORWF ANDWF 12.5 0xff IOCBF, W IOCBF, F Operation in Sleep The interrupt-on-change interrupt sequence will wake the device from Sleep mode, if the IOCIE bit is set. If an edge is detected while in Sleep mode, the IOCBF register will be updated prior to the first instruction executed out of Sleep. INTERRUPT-ON-CHANGE BLOCK DIAGRAM IOCIE IOCBNx D Q IOCBFx From all other IOCBFx individual pin detectors CK R IOC Interrupt to CPU Core RBx IOCBPx D Q CK R Q2 Clock Cycle DS40001455F-page 100  2011-2016 Microchip Technology Inc. PIC16LF1902/3 REGISTER 12-1: IOCBP: INTERRUPT-ON-CHANGE POSITIVE EDGE REGISTER R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 IOCBP7 IOCBP6 IOCBP5 IOCBP4 IOCBP3 IOCBP2 IOCBP1 IOCBP0 bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-0 IOCBP: Interrupt-on-Change Positive Edge Enable bits 1 = Interrupt-on-Change enabled on the pin for a positive going edge. Associated Status bit and interrupt flag will be set upon detecting an edge. 0 = Interrupt-on-Change disabled for the associated pin. REGISTER 12-2: IOCBN: INTERRUPT-ON-CHANGE NEGATIVE EDGE REGISTER R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 IOCBN7 IOCBN6 IOCBN5 IOCBN4 IOCBN3 IOCBN2 IOCBN1 IOCBN0 bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-0 IOCBN: Interrupt-on-Change Negative Edge Enable bits 1 = Interrupt-on-Change enabled on the pin for a negative going edge. Associated Status bit and interrupt flag will be set upon detecting an edge. 0 = Interrupt-on-Change disabled for the associated pin. REGISTER 12-3: IOCBF: INTERRUPT-ON-CHANGE FLAG REGISTER R/W/HS-0/0 R/W/HS-0/0 IOCBF7 IOCBF6 R/W/HS-0/0 R/W/HS-0/0 R/W/HS-0/0 IOCBF5 IOCBF4 IOCBF3 R/W/HS-0/0 R/W/HS-0/0 R/W/HS-0/0 IOCBF2 IOCBF1 IOCBF0 bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared HS - Bit is set in hardware bit 7-0 IOCBF: Interrupt-on-Change Flag bits 1 = An enabled change was detected on the associated pin. Set when IOCBPx = 1 and a rising edge was detected on RBx, or when IOCBNx = 1 and a falling edge was detected on RBx. 0 = No change was detected, or the user cleared the detected change.  2011-2016 Microchip Technology Inc. DS40001455F-page 101 PIC16LF1902/3 TABLE 12-1: SUMMARY OF REGISTERS ASSOCIATED WITH INTERRUPT-ON-CHANGE Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Register on Page ANSELB — — ANSB5 ANSB4 ANSB3 ANSB2 ANSB1 ANSB0 94 INTCON GIE PEIE TMR0IE INTE IOCIE TMR0IF INTF IOCIF 60 Name IOCBF IOCBF7 IOCBF6 IOCBF5 IOCBF4 IOCBF3 IOCBF2 IOCBF1 IOCBF0 101 IOCBN IOCBN7 IOCBN6 IOCBN5 IOCBN4 IOCBN3 IOCBN2 IOCBN1 IOCBN0 101 IOCBP IOCBP7 IOCBP6 IOCBP5 IOCBP4 IOCBP3 IOCBP2 IOCBP1 IOCBP0 101 TRISB TRISB7 TRISB6 TRISB5 TRISB4 TRISB3 TRISB2 TRISB1 TRISB0 93 Legend: — = unimplemented location, read as ‘0’. Shaded cells are not used by interrupt-on-change. DS40001455F-page 102  2011-2016 Microchip Technology Inc. PIC16LF1902/3 13.0 FIXED VOLTAGE REFERENCE (FVR) 13.1 Independent Gain Amplifiers The output of the FVR supplied to the ADC is routed through two independent programmable gain amplifiers. Each amplifier can be configured to amplify the reference voltage by 1x or 2x, to produce the two possible voltage levels. The Fixed Voltage Reference, or FVR, is a stable voltage reference, independent of VDD, with 1.024V or 2.048V selectable output levels. The output of the FVR can be configured as the FVR input channel on the ADC. The ADFVR bits of the FVRCON register are used to enable and configure the gain amplifier settings for the reference supplied to the ADC module. Reference Section 15.0 “Analog-to-Digital Converter (ADC) Module” for additional information. The FVR can be enabled by setting the FVREN bit of the FVRCON register. 13.2 FVR Stabilization Period When the Fixed Voltage Reference module is enabled, it requires time for the reference and amplifier circuits to stabilize. Once the circuits stabilize and are ready for use, the FVRRDY bit of the FVRCON register will be set. See Section 21.0 “Electrical Specifications” for the minimum delay requirement. FIGURE 13-1: VOLTAGE REFERENCE BLOCK DIAGRAM ADFVR 2 x1 x2 FVR BUFFER1 (To ADC Module) 1.024V Fixed Reference + FVREN FVRRDY - Any peripheral requiring the Fixed Reference (See Table 13-1) TABLE 13-1: PERIPHERALS REQUIRING THE FIXED VOLTAGE REFERENCE (FVR) Peripheral Conditions Description HFINTOSC FOSC = 100 and IRCF = 000x BOREN = 11 BOR always enabled. BOR BOREN = 10 and BORFS = 1 BOR disabled in Sleep mode, BOR Fast Start enabled. BOREN = 01 and BORFS = 1 BOR under software control, BOR Fast Start enabled.  Microchip Technology Inc. INTOSC is active and device is not in Sleep. DS40001455F-page 1032011-2016 PIC16LF1902/3 13.3 FVR Control Registers REGISTER 13-1: FVRCON: FIXED VOLTAGE REFERENCE CONTROL REGISTER R/W-0/0 R-q/q R/W-0/0 R/W-0/0 U-0 U-0 FVREN FVRRDY(1) TSEN TSRNG — — R/W-0/0 R/W-0/0 ADFVR bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared q = Value depends on condition bit 7 FVREN: Fixed Voltage Reference Enable bit 0 = Fixed Voltage Reference is disabled 1 = Fixed Voltage Reference is enabled bit 6 FVRRDY: Fixed Voltage Reference Ready Flag bit(1) 0 = Fixed Voltage Reference output is not ready or not enabled 1 = Fixed Voltage Reference output is ready for use bit 5 TSEN: Temperature Indicator Enable bit 0 = Temperature Indicator is disabled 1 = Temperature Indicator is enabled bit 4 TSRNG: Temperature Indicator Range Selection bit 0 = VOUT = VDD - 2VT (Low Range) 1 = VOUT = VDD - 4VT (High Range) bit 3-2 Unimplemented: Read as ‘0’ bit 1-0 ADFVR: ADC Fixed Voltage Reference Selection bit 00 = ADC Fixed Voltage Reference Peripheral output is off. 01 = ADC Fixed Voltage Reference Peripheral output is 1x (1.024V) 10 = ADC Fixed Voltage Reference Peripheral output is 2x (2.048V)(2) 11 = Reserved Note 1: 2: FVRRDY will output the true state of the band gap. Fixed Voltage Reference output cannot exceed VDD. TABLE 13-2: Name FVRCON Legend: SUMMARY OF REGISTERS ASSOCIATED WITH FIXED VOLTAGE REFERENCE Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Register on page FVREN FVRRDY TSEN TSRNG — — ADFVR1 ADFVR0 104 Shaded cells are not used with the Fixed Voltage Reference. DS40001455F-page 104  2011-2016 Microchip Technology Inc. PIC16LF1902/3 14.0 TEMPERATURE INDICATOR MODULE FIGURE 14-1: This family of devices is equipped with a temperature circuit designed to measure the operating temperature of the silicon die. The circuit’s range of operating temperature falls between of -40°C and +85°C. The output is a voltage that is proportional to the device temperature. The output of the temperature indicator is internally connected to the device ADC. VDD TSEN TSRNG The circuit may be used as a temperature threshold detector or a more accurate temperature indicator, depending on the level of calibration performed. A onepoint calibration allows the circuit to indicate a temperature closely surrounding that point. A two-point calibration allows the circuit to sense the entire range of temperature more accurately. Reference Application Note AN1333, “Use and Calibration of the Internal Temperature Indicator” (DS01333) for more details regarding the calibration process. 14.1 TEMPERATURE CIRCUIT DIAGRAM VOUT ADC MUX ADC n CHS bits (ADCON0 register) Circuit Operation Figure 14-1 shows a simplified block diagram of the temperature circuit. The proportional voltage output is achieved by measuring the forward voltage drop across multiple silicon junctions. Equation 14-1 describes the output characteristics of the temperature indicator. EQUATION 14-1: VOUT RANGES High Range: VOUT = VDD - 4VT Low Range: VOUT = VDD - 2VT 14.2 Minimum Operating VDD vs. Minimum Sensing Temperature When the temperature circuit is operated in low range, the device may be operated at any operating voltage that is within specifications. When the temperature circuit is operated in high range, the device operating voltage, VDD, must be high enough to ensure that the temperature circuit is correctly biased. Table 14-1 shows the recommended minimum VDD vs. range setting. TABLE 14-1: The temperature sense circuit is integrated with the Fixed Voltage Reference (FVR) module. See Section 13.0 “Fixed Voltage Reference (FVR)” for more information. The circuit is enabled by setting the TSEN bit of the FVRCON register. When disabled, the circuit draws no current. The circuit operates in either high or low range. The high range, selected by setting the TSRNG bit of the FVRCON register, provides a wider output voltage. This provides more resolution over the temperature range, but may be less consistent from part to part. This range requires a higher bias voltage to operate and thus, a higher VDD is needed. The low range is selected by clearing the TSRNG bit of the FVRCON register. The low range generates a lower voltage drop and thus, a lower bias voltage is needed to operate the circuit. The low range is provided for low voltage operation.  2011-2016 Microchip Technology Inc. RECOMMENDED VDD VS. RANGE Min. VDD, TSRNG = 1 Min. VDD, TSRNG = 0 3.6V 1.8V 14.3 Temperature Output The output of the circuit is measured using the internal Analog-to-Digital converter. A channel is reserved for the temperature circuit output. Refer to Section 15.0 “Analog-to-Digital Converter (ADC) Module” for detailed information. 14.4 ADC Acquisition Time To ensure accurate temperature measurements, the user must wait at least 200 s after the ADC input multiplexer is connected to the temperature indicator output before the conversion is performed. In addition, the user must wait 200 s between sequential conversions of the temperature indicator output. DS40001455F-page 105 PIC16LF1902/3 15.0 The ADC can generate an interrupt upon completion of a conversion. This interrupt can be used to wake-up the device from Sleep. ANALOG-TO-DIGITAL CONVERTER (ADC) MODULE The Analog-to-Digital Converter (ADC) allows conversion of an analog input signal to a 10-bit binary representation of that signal. This device uses analog inputs, which are multiplexed into a single sample and hold circuit. The output of the sample and hold is connected to the input of the converter. The converter generates a 10-bit binary result via successive approximation and stores the conversion result into the ADC result registers (ADRESH:ADRESL register pair). Figure 15-1 shows the block diagram of the ADC. The ADC voltage reference is software selectable to be either internally generated or externally supplied. FIGURE 15-1: ADC BLOCK DIAGRAM VDD ADPREF = 00 VREF+ AN0 00000 AN1 00001 AN2 00010 VREF+/AN3 00011 AN4 00100 Reserved 00101 Reserved 00110 Reserved 00111 AN8 01000 AN9 01001 AN10 01010 AN11 01011 AN12 01100 AN13 01101 ADPREF = 10 ADC 10 GO/DONE ADFM ADON(1) 16 VSS Temperature Indicator 11101 Reserved 11110 FVR Buffer1 11111 0 = Left Justify 1 = Right Justify ADRESH ADRESL CHS(2) Note 1: 2: When ADON = 0, all multiplexer inputs are disconnected. See ADCON0 register (Example 15-1) for detailed analog channel selection per device. DS40001455F-page 106  2011-2016 Microchip Technology Inc. PIC16LF1902/3 15.1 ADC Configuration When configuring and using the ADC the following functions must be considered: • • • • • • Port configuration Channel selection ADC voltage reference selection ADC conversion clock source Interrupt control Result formatting 15.1.1 PORT CONFIGURATION The ADC can be used to convert both analog and digital signals. When converting analog signals, the I/O pin should be configured for analog by setting the associated TRIS and ANSEL bits. Refer to Section 11.0 “I/O Ports” for more information. Note: 15.1.2 Analog voltages on any pin that is defined as a digital input may cause the input buffer to conduct excess current. CHANNEL SELECTION There are up to 11 channel selections available: • AN pins • Temperature Indicator • FVR (Fixed Voltage Reference) Output 15.1.4 CONVERSION CLOCK The source of the conversion clock is software selectable via the ADCS bits of the ADCON1 register. There are seven possible clock options: • • • • • • • FOSC/2 FOSC/4 FOSC/8 FOSC/16 FOSC/32 FOSC/64 FRC (dedicated internal oscillator) The time to complete one bit conversion is defined as TAD. One full 10-bit conversion requires 11.5 TAD periods as shown in Figure 15-2. For correct conversion, the appropriate TAD specification must be met. Refer to the A/D conversion requirements in Section 21.0 “Electrical Specifications” for more information. Table 15-1 gives examples of appropriate ADC clock selections. Note: Unless using the FRC, any changes in the system clock frequency will change the ADC clock frequency, which may adversely affect the ADC result. Refer to Section 13.0 “Fixed Voltage Reference (FVR)” and Section 14.0 “Temperature Indicator Module” for more information on these channel selections. The CHS bits of the ADCON0 register determine which channel is connected to the sample and hold circuit. When changing channels, a delay is required before starting the next conversion. Refer to Section 15.2 “ADC Operation” for more information. 15.1.3 ADC VOLTAGE REFERENCE The ADPREF bits of the ADCON1 register provides control of the positive voltage reference. The positive voltage reference can be: • VREF+ pin • VDD  2011-2016 Microchip Technology Inc. DS40001455F-page 107 PIC16LF1902/3 TABLE 15-1: ADC CLOCK PERIOD (TAD) VS. DEVICE OPERATING FREQUENCIES ADC Clock Period (TAD) Device Frequency (FOSC) ADC Clock Source ADCS 20 MHz 16 MHz 8 MHz 4 MHz 1 MHz FOSC/2 000 100 ns(2) 125 ns(2) 250 ns(2) 500 ns(2) 2.0 s FOSC/4 100 (2) 200 ns (2) 250 ns (2) FOSC/8 001 400 ns(2) 0.5 s(2) FOSC/16 101 800 ns 010 FOSC/64 FRC FOSC/32 Legend: Note 1: 2: 3: 4: 1.0 s 4.0 s 1.0 s 2.0 s 8.0 s(3) 1.0 s 2.0 s 4.0 s 16.0 s(3) 1.6 s 2.0 s 4.0 s 110 3.2 s 4.0 s x11 1.0-6.0 s(1,4) 1.0-6.0 s(1,4) 500 ns 8.0 s (3) 8.0 s 16.0 s (3) (3) 1.0-6.0 s(1,4) 1.0-6.0 s(1,4) 32.0 s(3) 64.0 s(3) 1.0-6.0 s(1,4) Shaded cells are outside of recommended range. The FRC source has a typical TAD time of 1.6 s for VDD. These values violate the minimum required TAD time. For faster conversion times, the selection of another clock source is recommended. The ADC clock period (TAD) and total ADC conversion time can be minimized when the ADC clock is derived from the system clock FOSC. However, the FRC clock source must be used when conversions are to be performed with the device in Sleep mode. FIGURE 15-2: ANALOG-TO-DIGITAL CONVERSION TAD CYCLES TCY - TAD TAD1 TAD2 TAD3 TAD4 TAD5 TAD6 TAD7 TAD8 TAD9 TAD10 TAD11 b4 b1 b0 b6 b7 b2 b9 b8 b3 b5 Conversion starts Holding capacitor is disconnected from analog input (typically 100 ns) Set GO bit On the following cycle: ADRESH:ADRESL is loaded, GO bit is cleared, ADIF bit is set, holding capacitor is connected to analog input. DS40001455F-page 108  2011-2016 Microchip Technology Inc. PIC16LF1902/3 15.1.5 INTERRUPTS 15.1.6 The ADC module allows for the ability to generate an interrupt upon completion of an Analog-to-Digital conversion. The ADC Interrupt Flag is the ADIF bit in the PIR1 register. The ADC Interrupt Enable is the ADIE bit in the PIE1 register. The ADIF bit must be cleared in software. RESULT FORMATTING The 10-bit A/D conversion result can be supplied in two formats, left justified or right justified. The ADFM bit of the ADCON1 register controls the output format. Figure 15-3 shows the two output formats. Note 1: The ADIF bit is set at the completion of every conversion, regardless of whether or not the ADC interrupt is enabled. 2: The ADC operates during Sleep only when the FRC oscillator is selected. This interrupt can be generated while the device is operating or while in Sleep. If the device is in Sleep, the interrupt will wake-up the device. Upon waking from Sleep, the next instruction following the SLEEP instruction is always executed. If the user is attempting to wake-up from Sleep and resume in-line code execution, the GIE and PEIE bits of the INTCON register must be disabled. If the GIE and PEIE bits of the INTCON register are enabled, execution will switch to the Interrupt Service Routine. FIGURE 15-3: 10-BIT A/D CONVERSION RESULT FORMAT ADRESH (ADFM = 0) ADRESL MSB LSB bit 7 bit 0 bit 7 Unimplemented: Read as ‘0’ 10-bit A/D Result (ADFM = 1) bit 0 MSB bit 7 Unimplemented: Read as ‘0’  2011-2016 Microchip Technology Inc. LSB bit 0 bit 7 bit 0 10-bit A/D Result DS40001455F-page 109 PIC16LF1902/3 15.2 15.2.1 ADC Operation STARTING A CONVERSION To enable the ADC module, the ADON bit of the ADCON0 register must be set to a ‘1’. Setting the GO/DONE bit of the ADCON0 register to a ‘1’ will start the Analog-to-Digital conversion. Note: 15.2.2 The GO/DONE bit should not be set in the same instruction that turns on the ADC. Refer to Section 15.2.5 “A/D Conversion Procedure”. COMPLETION OF A CONVERSION When the conversion is complete, the ADC module will: • Clear the GO/DONE bit • Set the ADIF Interrupt Flag bit • Update the ADRESH and ADRESL registers with new conversion result 15.2.3 15.2.4 ADC OPERATION DURING SLEEP The ADC module can operate during Sleep. This requires the ADC clock source to be set to the FRC option. When the FRC clock source is selected, the ADC waits one additional instruction before starting the conversion. This allows the SLEEP instruction to be executed, which can reduce system noise during the conversion. If the ADC interrupt is enabled, the device will wake-up from Sleep when the conversion completes. If the ADC interrupt is disabled, the ADC module is turned off after the conversion completes, although the ADON bit remains set. When the ADC clock source is something other than FRC, a SLEEP instruction causes the present conversion to be aborted and the ADC module is turned off, although the ADON bit remains set. TERMINATING A CONVERSION If a conversion must be terminated before completion, the GO/DONE bit can be cleared in software. The ADRESH and ADRESL registers will be updated with the partially complete Analog-to-Digital conversion sample. Incomplete bits will match the last bit converted. Note: A device Reset forces all registers to their Reset state. Thus, the ADC module is turned off and any pending conversion is terminated. DS40001455F-page 110  2011-2016 Microchip Technology Inc. PIC16LF1902/3 15.2.5 A/D CONVERSION PROCEDURE This is an example procedure for using the ADC to perform an Analog-to-Digital conversion: 1. 2. 3. 4. 5. 6. 7. 8. Configure Port: • Disable pin output driver (Refer to the TRIS register) • Configure pin as analog (Refer to the ANSEL register) Configure the ADC module: • Select ADC conversion clock • Configure voltage reference • Select ADC input channel • Turn on ADC module Configure ADC interrupt (optional): • Clear ADC interrupt flag • Enable ADC interrupt • Enable peripheral interrupt • Enable global interrupt(1) Wait the required acquisition time(2). Start conversion by setting the GO/DONE bit. Wait for ADC conversion to complete by one of the following: • Polling the GO/DONE bit • Waiting for the ADC interrupt (interrupts enabled) Read ADC Result. Clear the ADC interrupt flag (required if interrupt is enabled). EXAMPLE 15-1: A/D CONVERSION ;This code block configures the ADC ;for polling, Vdd and Vss references, Frc ;clock and AN0 input. ; ;Conversion start & polling for completion ; are included. ; BANKSEL ADCON1 ; MOVLW B’11110000’ ;Right justify, Frc ;clock MOVWF ADCON1 ;Vdd and Vss Vref BANKSEL TRISA ; BSF TRISA,0 ;Set RA0 to input BANKSEL ANSEL ; BSF ANSEL,0 ;Set RA0 to analog BANKSEL ADCON0 ; MOVLW B’00000001’ ;Select channel AN0 MOVWF ADCON0 ;Turn ADC On CALL SampleTime ;Acquisiton delay BSF ADCON0,ADGO ;Start conversion BTFSC ADCON0,ADGO ;Is conversion done? GOTO $-1 ;No, test again BANKSEL ADRESH ; MOVF ADRESH,W ;Read upper 2 bits MOVWF RESULTHI ;store in GPR space BANKSEL ADRESL ; MOVF ADRESL,W ;Read lower 8 bits MOVWF RESULTLO ;Store in GPR space Note 1: The global interrupt can be disabled if the user is attempting to wake-up from Sleep and resume in-line code execution. 2: Refer to Section 15.3 “A/D Acquisition Requirements”.  2011-2016 Microchip Technology Inc. DS40001455F-page 111 PIC16LF1902/3 15.2.6 ADC REGISTER DEFINITIONS The following registers are used to control the operation of the ADC. REGISTER 15-1: U-0 ADCON0: A/D CONTROL REGISTER 0 R/W-0/0 R/W-0/0 — R/W-0/0 R/W-0/0 R/W-0/0 CHS R/W-0/0 R/W-0/0 GO/DONE ADON bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7 Unimplemented: Read as ‘0’ bit 6-2 CHS: Analog Channel Select bits 00000 = AN0 00001 = AN1 00010 = AN2 00011 = AN3 00100 = AN4 00101 = Reserved. No channel connected. 00110 = Reserved. No channel connected. 00111 = Reserved. No channel connected. 01000 = AN8 01001 = AN9 01010 = AN10 01011 = AN11 01100 = AN12 01101 = AN13 01110 = Reserved. No channel connected. • • • 11100 = Reserved. No channel connected. 11101 = Temperature Indicator(2) 11110 = Reserved. No channel connected. 11111 = FVR (Fixed Voltage Reference) Buffer 1 Output(1) bit 1 GO/DONE: A/D Conversion Status bit 1 = A/D conversion cycle in progress. Setting this bit starts an A/D conversion cycle. This bit is automatically cleared by hardware when the A/D conversion has completed. 0 = A/D conversion completed/not in progress bit 0 ADON: ADC Enable bit 1 = ADC is enabled 0 = ADC is disabled and consumes no operating current Note 1: 2: See Section 13.0 “Fixed Voltage Reference (FVR)” for more information. See Section 14.0 “Temperature Indicator Module” for more information. DS40001455F-page 112  2011-2016 Microchip Technology Inc. PIC16LF1902/3 REGISTER 15-2: R/W-0/0 ADCON1: A/D CONTROL REGISTER 1 R/W-0/0 ADFM R/W-0/0 R/W-0/0 ADCS U-0 U-0 — — R/W-0/0 R/W-0/0 ADPREF bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7 ADFM: A/D Result Format Select bit 1 = Right justified. Six Most Significant bits of ADRESH are set to ‘0’ when the conversion result is loaded. 0 = Left justified. Six Least Significant bits of ADRESL are set to ‘0’ when the conversion result is loaded. bit 6-4 ADCS: A/D Conversion Clock Select bits 000 = FOSC/2 001 = FOSC/8 010 = FOSC/32 011 = FRC (clock supplied from a dedicated RC oscillator) 100 = FOSC/4 101 = FOSC/16 110 = FOSC/64 111 = FRC (clock supplied from a dedicated RC oscillator) bit 3-2 Unimplemented: Read as ‘0’ bit 1-0 ADPREF: A/D Positive Voltage Reference Configuration bits 00 = VREF+ is connected to VDD 01 = Reserved 10 = VREF+ is connected to external VREF+ pin(1) 11 = Reserved Note 1: When selecting the FVR or the VREF+ pin as the source of the positive reference, be aware that a minimum voltage specification exists. See Section 21.0 “Electrical Specifications” for details.  2011-2016 Microchip Technology Inc. DS40001455F-page 113 PIC16LF1902/3 REGISTER 15-3: R/W-x/u ADRESH: ADC RESULT REGISTER HIGH (ADRESH) ADFM = 0 R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u ADRES bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-0 ADRES: ADC Result Register bits Upper eight bits of 10-bit conversion result REGISTER 15-4: R/W-x/u ADRESL: ADC RESULT REGISTER LOW (ADRESL) ADFM = 0 R/W-x/u ADRES R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u — — — — — — bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-6 ADRES: ADC Result Register bits Lower two bits of 10-bit conversion result bit 5-0 Reserved: Do not use. DS40001455F-page 114  2011-2016 Microchip Technology Inc. PIC16LF1902/3 REGISTER 15-5: ADRESH: ADC RESULT REGISTER HIGH (ADRESH) ADFM = 1 R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u — — — — — — R/W-x/u R/W-x/u ADRES bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-2 Reserved: Do not use. bit 1-0 ADRES: ADC Result Register bits Upper two bits of 10-bit conversion result REGISTER 15-6: R/W-x/u ADRESL: ADC RESULT REGISTER LOW (ADRESL) ADFM = 1 R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u ADRES bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-0 ADRES: ADC Result Register bits Lower eight bits of 10-bit conversion result  2011-2016 Microchip Technology Inc. DS40001455F-page 115 PIC16LF1902/3 15.3 A/D Acquisition Requirements For the ADC to meet its specified accuracy, the charge holding capacitor (CHOLD) must be allowed to fully charge to the input channel voltage level. The Analog Input model is shown in Figure 15-4. The source impedance (RS) and the internal sampling switch (RSS) impedance directly affect the time required to charge the capacitor CHOLD. The sampling switch (RSS) impedance varies over the device voltage (VDD), refer to Figure 15-4. The maximum recommended impedance for analog sources is 10 k. As the EQUATION 15-1: Assumptions: source impedance is decreased, the acquisition time may be decreased. After the analog input channel is selected (or changed), an A/D acquisition must be done before the conversion can be started. To calculate the minimum acquisition time, Equation 15-1 may be used. This equation assumes that 1/2 LSb error is used (1,024 steps for the ADC). The 1/2 LSb error is the maximum error allowed for the ADC to meet its specified resolution. ACQUISITION TIME EXAMPLE Temperature = 50°C and external impedance of 10k  5.0V V DD T ACQ = Amplifier Settling Time + Hold Capacitor Charging Time + Temperature Coefficient = T AMP + T C + T COFF = 2µs + T C +   Temperature - 25°C   0.05µs/°C   The value for TC can be approximated with the following equations: 1  = V CHOLD V AP P LI ED  1 – -------------------------n+1   2 –1 ;[1] VCHOLD charged to within 1/2 lsb –TC ----------  RC V AP P LI ED  1 – e  = V CHOLD   ;[2] VCHOLD charge response to VAPPLIED – Tc ---------  1 RC  ;combining [1] and [2] V AP P LI ED  1 – e  = V A PP LIE D  1 – -------------------------n+1    2 –1 Note: Where n = number of bits of the ADC. Solving for TC: T C = – C HOLD  R IC + R SS + R S  ln(1/2047) = – 12.5pF  1k  + 7k  + 10k   ln(0.0004885) = 1.715 µs Therefore: T A CQ = 2µs + 1.715µs +   50°C- 25°C   0.05 µs/°C   = 4.96µs Note 1: The reference voltage (VREF) has no effect on the equation, since it cancels itself out. 2: The charge holding capacitor (CHOLD) is not discharged after each conversion. 3: The maximum recommended impedance for analog sources is 10 k. This is required to meet the pin leakage specification. DS40001455F-page 116  2011-2016 Microchip Technology Inc. PIC16LF1902/3 FIGURE 15-4: ANALOG INPUT MODEL VDD Analog Input pin Rs VT  0.6V CPIN 5 pF VA RIC  1k Sampling Switch SS Rss I LEAKAGE(1) VT  0.6V CHOLD = 12.5 pF VSS/VREF- Legend: CHOLD CPIN 6V 5V VDD 4V 3V 2V = Sample/Hold Capacitance = Input Capacitance RSS I LEAKAGE = Leakage current at the pin due to various junctions RIC = Interconnect Resistance RSS = Resistance of Sampling Switch SS = Sampling Switch VT = Threshold Voltage 5 6 7 8 9 10 11 Sampling Switch (k) Note 1: Refer to Section 21.0 “Electrical Specifications”. FIGURE 15-5: ADC TRANSFER FUNCTION Full-Scale Range 3FFh 3FEh ADC Output Code 3FDh 3FCh 3FBh 03h 02h 01h 00h Analog Input Voltage 0.5 LSB VREF-  2011-2016 Microchip Technology Inc. Zero-Scale Transition 1.5 LSB Full-Scale Transition VREF+ DS40001455F-page 117 PIC16LF1902/3 TABLE 15-2: Name SUMMARY OF REGISTERS ASSOCIATED WITH ADC Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Register on Page ADCON0 — CHS4 CHS3 CHS2 CHS1 CHS0 GO/DONE ADON 112 ADCON1 ADFM ADCS2 ADCS1 ADCS0 — — ADPREF1 ADPREF0 113 ADRESH A/D Result Register High ADRESL A/D Result Register Low 114, 115 114, 115 ANSELA — — ANSA5 — ANSA3 ANSA2 ANSA1 ANSA0 ANSELB — — ANSB5 ANSB4 ANSB3 ANSB2 ANSB1 ANSB0 94 INTCON GIE PEIE TMR0IE INTE IOCIE TMR0IF INTF IOCIF 60 PIE1 TMR1GIE ADIE — — — — — TMR1IE 61 PIR1 TMR1GIF ADIF — — — — — TMR1IF 63 TRISA TRISA7 TRISA6 TRISA5 TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 90 TRISB TRISB7 TRISB6 TRISB5 TRISB4 TRISB3 TRISB2 TRISB1 TRISB0 93 FVRCON FVREN FVRRDY TSEN TSRNG — — ADFVR1 ADFVR0 104 Legend: 91 x = unknown, u = unchanged, — = unimplemented read as ‘0’, q = value depends on condition. Shaded cells are not used for ADC module. DS40001455F-page 118  2011-2016 Microchip Technology Inc. PIC16LF1902/3 16.0 16.1.2 TIMER0 MODULE 8-BIT COUNTER MODE The Timer0 module is an 8-bit timer/counter with the following features: In 8-Bit Counter mode, the Timer0 module will increment on every rising or falling edge of the T0CKI pin. • • • • • • 8-Bit Counter mode using the T0CKI pin is selected by setting the TMR0CS bit in the OPTION_REG register to ‘1’. 8-bit timer/counter register (TMR0) 8-bit prescaler (independent of Watchdog Timer) Programmable internal or external clock source Programmable external clock edge selection Interrupt on overflow TMR0 can be used to gate Timer1 The rising or falling transition of the incrementing edge for either input source is determined by the TMR0SE bit in the OPTION_REG register. Figure 16-1 is a block diagram of the Timer0 module. 16.1 Timer0 Operation The Timer0 module can be used as either an 8-bit timer or an 8-bit counter. 16.1.1 8-BIT TIMER MODE The Timer0 module will increment every instruction cycle, if used without a prescaler. 8-Bit Timer mode is selected by clearing the TMR0CS bit of the OPTION_REG register. When TMR0 is written, the increment is inhibited for two instruction cycles immediately following the write. Note: The value written to the TMR0 register can be adjusted, in order to account for the two instruction cycle delay when TMR0 is written. FIGURE 16-1: BLOCK DIAGRAM OF THE TIMER0 FOSC/4 Data Bus 0 8 T0CKI 1 Sync 2 TCY 1 TMR0 0 TMR0SE TMR0CS 8-bit Prescaler PSA Set Flag bit TMR0IF on Overflow Overflow to Timer1 8 PS  2011-2016 Microchip Technology Inc. DS40001455F-page 119 PIC16LF1902/3 16.1.3 SOFTWARE PROGRAMMABLE PRESCALER A software programmable prescaler is available for exclusive use with Timer0. The prescaler is enabled by clearing the PSA bit of the OPTION_REG register. Note: The Watchdog Timer (WDT) uses its own independent prescaler. There are eight prescaler options for the Timer0 module ranging from 1:2 to 1:256. The prescale values are selectable via the PS bits of the OPTION_REG register. In order to have a 1:1 prescaler value for the Timer0 module, the prescaler must be disabled by setting the PSA bit of the OPTION_REG register. The prescaler is not readable or writable. All instructions writing to the TMR0 register will clear the prescaler. 16.1.4 TIMER0 INTERRUPT Timer0 will generate an interrupt when the TMR0 register overflows from FFh to 00h. The TMR0IF interrupt flag bit of the INTCON register is set every time the TMR0 register overflows, regardless of whether or not the Timer0 interrupt is enabled. The TMR0IF bit can only be cleared in software. The Timer0 interrupt enable is the TMR0IE bit of the INTCON register. Note: 16.1.5 The Timer0 interrupt cannot wake the processor from Sleep since the timer is frozen during Sleep. 8-BIT COUNTER MODE SYNCHRONIZATION When in 8-Bit Counter mode, the incrementing edge on the T0CKI pin must be synchronized to the instruction clock. Synchronization can be accomplished by sampling the prescaler output on the Q2 and Q4 cycles of the instruction clock. The high and low periods of the external clocking source must meet the timing requirements as shown in Section 21.0 “Electrical Specifications”. 16.1.6 OPERATION DURING SLEEP Timer0 cannot operate while the processor is in Sleep mode. The contents of the TMR0 register will remain unchanged while the processor is in Sleep mode. DS40001455F-page 120  2011-2016 Microchip Technology Inc. PIC16LF1902/3 16.2 Option and Timer0 Control Register REGISTER 16-1: OPTION_REG: OPTION REGISTER R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1 WPUEN INTEDG TMR0CS TMR0SE PSA R/W-1/1 R/W-1/1 R/W-1/1 PS bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7 WPUEN: Weak Pull-up Enable bit 1 = All weak pull-ups are disabled (except MCLR, if it is enabled) 0 = Weak pull-ups are enabled by individual WPUx latch values bit 6 INTEDG: Interrupt Edge Select bit 1 = Interrupt on rising edge of INT pin 0 = Interrupt on falling edge of INT pin bit 5 TMR0CS: Timer0 Clock Source Select bit 1 = Transition on T0CKI pin 0 = Internal instruction cycle clock (FOSC/4) bit 4 TMR0SE: Timer0 Source Edge Select bit 1 = Increment on high-to-low transition on T0CKI pin 0 = Increment on low-to-high transition on T0CKI pin bit 3 PSA: Prescaler Assignment bit 1 = Prescaler is not assigned to the Timer0 module 0 = Prescaler is assigned to the Timer0 module bit 2-0 PS: Prescaler Rate Select bits TABLE 16-1: Name INTCON TRISA Timer0 Rate 000 001 010 011 100 101 110 111 1:2 1:4 1:8 1 : 16 1 : 32 1 : 64 1 : 128 1 : 256 SUMMARY OF REGISTERS ASSOCIATED WITH TIMER0 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Register on Page GIE PEIE TMR0IE INTE IOCIE TMR0IF INTF IOCIF 60 OPTION_REG WPUEN TMR0 Bit Value INTEDG TMR0CS TMR0SE PSA PS 121 Timer0 Module Register TRISA7 TRISA6 TRISA5 119* TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 90 Legend: — = Unimplemented location, read as ‘0’. Shaded cells are not used by the Timer0 module. * Page provides register information.  2011-2016 Microchip Technology Inc. DS40001455F-page 121 PIC16LF1902/3 17.0 Figure 17-1 is a block diagram of the Timer1 module. TIMER1 MODULE WITH GATE CONTROL The Timer1 module is a 16-bit timer/counter with the following features: • • • • • • • • • • • • 16-bit timer/counter register pair (TMR1H:TMR1L) Programmable internal or external clock source 2-bit prescaler Dedicated 32 kHz oscillator circuit Multiple Timer1 gate (count enable) sources Interrupt on overflow Wake-up on overflow (external clock, Asynchronous mode only) Selectable Gate Source Polarity Gate Toggle mode Gate Single-pulse mode Gate Value Status Gate Event Interrupt FIGURE 17-1: TIMER1 BLOCK DIAGRAM T1GSS T1G T1GSPM 0 From Timer0 Overflow 0 T1G_IN 1 T1GVAL 0 Single Pulse TMR1ON T1GPOL D Q CK R Q 1 Acq. Control 1 Q1 Data Bus D Q RD T1GCON EN Interrupt T1GGO/DONE det Set TMR1GIF T1GTM TMR1GE Set flag bit TMR1IF on Overflow TMR1ON TMR1(2) TMR1H EN TMR1L Q D T1CLK Synchronized clock input 0 1 TMR1CS T1OSO Reserved T1OSC T1OSI T1SYNC OUT 11 1 Synchronize(3) Prescaler 1, 2, 4, 8 det 10 EN 0 T1OSCEN (1) FOSC Internal Clock 01 FOSC/4 Internal Clock 00 2 T1CKPS FOSC/2 Internal Clock Sleep input T1CKI To LCD and Clock Switching Modules Note 1: ST Buffer is high speed type when using T1CKI. 2: Timer1 register increments on rising edge. 3: Synchronize does not operate while in Sleep. DS40001455F-page 122  2011-2016 Microchip Technology Inc. PIC16LF1902/3 17.1 Timer1 Operation 17.2 The Timer1 module is a 16-bit incrementing counter which is accessed through the TMR1H:TMR1L register pair. Writes to TMR1H or TMR1L directly update the counter. The TMR1CS and T1OSCEN bits of the T1CON register are used to select the clock source for Timer1. Table 17-2 displays the clock source selections. 17.2.1 When used with an internal clock source, the module is a timer and increments on every instruction cycle. When used with an external clock source, the module can be used as either a timer or counter and increments on every selected edge of the external source. INTERNAL CLOCK SOURCE When the internal clock source is selected the TMR1H:TMR1L register pair will increment on multiples of FOSC as determined by the Timer1 prescaler. When the FOSC internal clock source is selected, the Timer1 register value will increment by four counts every instruction clock cycle. Due to this condition, a 2 LSB error in resolution will occur when reading the Timer1 value. To utilize the full resolution of Timer1, an asynchronous input signal must be used to gate the Timer1 clock input. Timer1 is enabled by configuring the TMR1ON and TMR1GE bits in the T1CON and T1GCON registers, respectively. Table 17-1 displays the Timer1 enable selections. TABLE 17-1: Clock Source Selection TIMER1 ENABLE SELECTIONS The following asynchronous source may be used: • Asynchronous event on the T1G pin to Timer1 gate Timer1 Operation TMR1ON TMR1GE 0 0 Off 17.2.2 0 1 Off 1 0 Always On When the external clock source is selected, the Timer1 module may work as a timer or a counter. 1 1 Count Enabled EXTERNAL CLOCK SOURCE When enabled to count, Timer1 is incremented on the rising edge of the external clock input T1CKI or the capacitive sensing oscillator signal. Either of these external clock sources can be synchronized to the microcontroller system clock or they can run asynchronously. When used as a timer with a clock oscillator, an external 32.768 kHz crystal can be used in conjunction with the dedicated internal oscillator circuit. Note: In Counter mode, a falling edge must be registered by the counter prior to the first incrementing rising edge after any one or more of the following conditions: • • • • TABLE 17-2: TMR1CS1 Timer1 enabled after POR Write to TMR1H or TMR1L Timer1 is disabled Timer1 is disabled (TMR1ON = 0) when T1CKI is high then Timer1 is enabled (TMR1ON=1) when T1CKI is low. CLOCK SOURCE SELECTIONS TMR1CS0 T1OSCEN Clock Source 0 0 x Instruction Clock (FOSC/4) 0 1 x System Clock (FOSC) 1 0 0 External Clocking on T1CKI Pin 1 0 1 Osc. Circuit on T1OSI/T1OSO Pins 1 1 x Reserved  2011-2016 Microchip Technology Inc. DS40001455F-page 123 PIC16LF1902/3 17.3 Timer1 Prescaler Timer1 has four prescaler options allowing 1, 2, 4 or 8 divisions of the clock input. The T1CKPS bits of the T1CON register control the prescale counter. The prescale counter is not directly readable or writable; however, the prescaler counter is cleared upon a write to TMR1H or TMR1L. 17.6 Timer1 can be configured to count freely or the count can be enabled and disabled using Timer1 gate circuitry. This is also referred to as Timer1 Gate Enable. Timer1 gate can also be driven by multiple selectable sources. 17.6.1 17.4 Timer1 Oscillator A dedicated low-power 32.768 kHz oscillator circuit is built-in between pins T1OSI (input) and T1OSO. This internal circuit is to be used in conjunction with an external 32.768 kHz crystal. The oscillator circuit is enabled by setting the T1OSCEN bit of the T1CON register. The oscillator will continue to run during Sleep. Note: 17.5 The oscillator requires a start-up and stabilization time before use. Thus, T1OSCEN should be set and a suitable delay observed prior to enabling Timer1. Timer1 Operation in Asynchronous Counter Mode If control bit T1SYNC of the T1CON register is set, the external clock input is not synchronized. The timer increments asynchronously to the internal phase clocks. If the external clock source is selected then the timer will continue to run during Sleep and can generate an interrupt on overflow, which will wake-up the processor. However, special precautions in software are needed to read/write the timer (see Section 17.5.1 “Reading and Writing Timer1 in Asynchronous Counter Mode”). Note: 17.5.1 When switching from synchronous to asynchronous operation, it is possible to skip an increment. When switching from asynchronous to synchronous operation, it is possible to produce an additional increment. READING AND WRITING TIMER1 IN ASYNCHRONOUS COUNTER MODE Timer1 Gate TIMER1 GATE ENABLE The Timer1 Gate Enable mode is enabled by setting the TMR1GE bit of the T1GCON register. The polarity of the Timer1 Gate Enable mode is configured using the T1GPOL bit of the T1GCON register. When Timer1 Gate Enable mode is enabled, Timer1 will increment on the rising edge of the Timer1 clock source. When Timer1 Gate Enable mode is disabled, no incrementing will occur and Timer1 will hold the current count. See Figure 17-3 for timing details. TABLE 17-3: TIMER1 GATE ENABLE SELECTIONS T1CLK T1GPOL T1G  0 0 Counts  0 1 Holds Count  1 0 Holds Count  1 1 Counts 17.6.2 Timer1 Operation TIMER1 GATE SOURCE SELECTION The Timer1 gate source can be selected from one of four different sources. Source selection is controlled by the T1GSS bits of the T1GCON register. The polarity for each available source is also selectable. Polarity selection is controlled by the T1GPOL bit of the T1GCON register. TABLE 17-4: T1GSS TIMER1 GATE SOURCES Timer1 Gate Source 00 Timer1 Gate Pin 01 Overflow of Timer0 (TMR0 increments from FFh to 00h) Reading TMR1H or TMR1L while the timer is running from an external asynchronous clock will ensure a valid read (taken care of in hardware). However, the user should keep in mind that reading the 16-bit timer in two 8-bit values itself, poses certain problems, since the timer may overflow between the reads. For writes, it is recommended that the user simply stop the timer and write the desired values. A write contention may occur by writing to the timer registers, while the register is incrementing. This may produce an unpredictable value in the TMR1H:TMR1L register pair. DS40001455F-page 124  2011-2016 Microchip Technology Inc. PIC16LF1902/3 17.6.2.1 T1G Pin Gate Operation The T1G pin is one source for Timer1 gate control. It can be used to supply an external source to the Timer1 gate circuitry. 17.6.2.2 Timer0 Overflow Gate Operation When Timer0 increments from FFh to 00h, a low-to-high pulse will automatically be generated and internally supplied to the Timer1 gate circuitry. 17.6.3 TIMER1 GATE TOGGLE MODE When Timer1 Gate Toggle mode is enabled, it is possible to measure the full-cycle length of a Timer1 gate signal, as opposed to the duration of a single level pulse. The Timer1 gate source is routed through a flip-flop that changes state on every incrementing edge of the signal. See Figure 17-4 for timing details. Timer1 Gate Toggle mode is enabled by setting the T1GTM bit of the T1GCON register. When the T1GTM bit is cleared, the flip-flop is cleared and held clear. This is necessary in order to control which edge is measured. Note: Enabling Toggle mode at the same time as changing the gate polarity may result in indeterminate operation. 17.6.4 TIMER1 GATE SINGLE-PULSE MODE When Timer1 Gate Single-Pulse mode is enabled, it is possible to capture a single pulse gate event. Timer1 Gate Single-Pulse mode is first enabled by setting the T1GSPM bit in the T1GCON register. Next, the T1GGO/DONE bit in the T1GCON register must be set. The Timer1 will be fully enabled on the next incrementing edge. On the next trailing edge of the pulse, the T1GGO/DONE bit will automatically be cleared. No other gate events will be allowed to increment Timer1 until the T1GGO/DONE bit is once again set in software. See Figure 17-5 for timing details. If the Single Pulse Gate mode is disabled by clearing the T1GSPM bit in the T1GCON register, the T1GGO/DONE bit should also be cleared. Enabling the Toggle mode and the Single-Pulse mode simultaneously will permit both sections to work together. This allows the cycle times on the Timer1 gate source to be measured. See Figure 17-6 for timing details. 17.6.5 TIMER1 GATE VALUE STATUS When Timer1 gate value status is utilized, it is possible to read the most current level of the gate control value. The value is stored in the T1GVAL bit in the T1GCON register. The T1GVAL bit is valid even when the Timer1 gate is not enabled (TMR1GE bit is cleared). 17.6.6 TIMER1 GATE EVENT INTERRUPT When Timer1 Gate Event Interrupt is enabled, it is possible to generate an interrupt upon the completion of a gate event. When the falling edge of T1GVAL occurs, the TMR1GIF flag bit in the PIR1 register will be set. If the TMR1GIE bit in the PIE1 register is set, then an interrupt will be recognized. The TMR1GIF flag bit operates even when the Timer1 gate is not enabled (TMR1GE bit is cleared).  2011-2016 Microchip Technology Inc. DS40001455F-page 125 PIC16LF1902/3 17.7 Timer1 Interrupt The Timer1 register pair (TMR1H:TMR1L) increments to FFFFh and rolls over to 0000h. When Timer1 rolls over, the Timer1 interrupt flag bit of the PIR1 register is set. To enable the interrupt on rollover, you must set these bits: • • • • TMR1ON bit of the T1CON register TMR1IE bit of the PIE1 register PEIE bit of the INTCON register GIE bit of the INTCON register The interrupt is cleared by clearing the TMR1IF bit in the Interrupt Service Routine. Note: The TMR1H:TMR1L register pair and the TMR1IF bit should be cleared before enabling interrupts. 17.8 Timer1 Operation During Sleep Timer1 can only operate during Sleep when setup in Asynchronous Counter mode. In this mode, an external crystal or clock source can be used to increment the counter. To set up the timer to wake the device: • • • • • TMR1ON bit of the T1CON register must be set TMR1IE bit of the PIE1 register must be set PEIE bit of the INTCON register must be set T1SYNC bit of the T1CON register must be set TMR1CS bits of the T1CON register must be configured • T1OSCEN bit of the T1CON register must be configured The device will wake-up on an overflow and execute the next instructions. If the GIE bit of the INTCON register is set, the device will call the Interrupt Service Routine. Timer1 oscillator will continue to operate in Sleep regardless of the T1SYNC bit setting. FIGURE 17-2: TIMER1 INCREMENTING EDGE T1CKI = 1 when TMR1 Enabled T1CKI = 0 when TMR1 Enabled Note 1: 2: Arrows indicate counter increments. In Counter mode, a falling edge must be registered by the counter prior to the first incrementing rising edge of the clock. DS40001455F-page 126  2011-2016 Microchip Technology Inc. PIC16LF1902/3 FIGURE 17-3: TIMER1 GATE ENABLE MODE TMR1GE T1GPOL T1G_IN T1CKI T1GVAL Timer1 N FIGURE 17-4: N+1 N+2 N+3 N+4 TIMER1 GATE TOGGLE MODE TMR1GE T1GPOL T1GTM T1G_IN T1CKI T1GVAL Timer1 N  2011-2016 Microchip Technology Inc. N+1 N+2 N+3 N+4 N+5 N+6 N+7 N+8 DS40001455F-page 127 PIC16LF1902/3 FIGURE 17-5: TIMER1 GATE SINGLE-PULSE MODE TMR1GE T1GPOL T1GSPM T1GGO/ Cleared by hardware on falling edge of T1GVAL Set by software DONE Counting enabled on rising edge of T1G T1G_IN T1CKI T1GVAL Timer1 TMR1GIF DS40001455F-page 128 N Cleared by software N+1 N+2 Set by hardware on falling edge of T1GVAL Cleared by software  2011-2016 Microchip Technology Inc. PIC16LF1902/3 FIGURE 17-6: TIMER1 GATE SINGLE-PULSE AND TOGGLE COMBINED MODE TMR1GE T1GPOL T1GSPM T1GTM T1GGO/ Cleared by hardware on falling edge of T1GVAL Set by software DONE Counting enabled on rising edge of T1G T1G_IN T1CKI T1GVAL Timer1 TMR1GIF N Cleared by software  2011-2016 Microchip Technology Inc. N+1 N+2 N+3 Set by hardware on falling edge of T1GVAL N+4 Cleared by software DS40001455F-page 129 PIC16LF1902/3 17.9 Timer1 Control Register The Timer1 Control register (T1CON), shown in Register 17-1, is used to control Timer1 and select the various features of the Timer1 module. REGISTER 17-1: R/W-0/u T1CON: TIMER1 CONTROL REGISTER R/W-0/u TMR1CS R/W-0/u R/W-0/u T1CKPS R/W-0/u R/W-0/u U-0 R/W-0/u T1OSCEN T1SYNC — TMR1ON bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-6 TMR1CS: Timer1 Clock Source Select bits 11 = Reserved 10 = Timer1 clock source is pin or oscillator: If T1OSCEN = 0: External clock from T1CKI pin (on the rising edge) If T1OSCEN = 1: Crystal oscillator on T1OSI/T1OSO pins 01 = Timer1 clock source is system clock (FOSC) 00 = Timer1 clock source is instruction clock (FOSC/4) bit 5-4 T1CKPS: Timer1 Input Clock Prescale Select bits 11 = 1:8 Prescale value 10 = 1:4 Prescale value 01 = 1:2 Prescale value 00 = 1:1 Prescale value bit 3 T1OSCEN: LP Oscillator Enable Control bit 1 = Dedicated Timer1 oscillator circuit enabled 0 = Dedicated Timer1 oscillator circuit disabled bit 2 T1SYNC: Timer1 External Clock Input Synchronization Control bit TMR1CS = 1X 1 = Do not synchronize external clock input 0 = Synchronize external clock input with system clock (FOSC) TMR1CS = 0X This bit is ignored. Timer1 uses the internal clock when TMR1CS = 1X. bit 1 Unimplemented: Read as ‘0’ bit 0 TMR1ON: Timer1 On bit 1 = Enables Timer1 0 = Stops Timer1 Clears Timer1 gate flip-flop DS40001455F-page 130  2011-2016 Microchip Technology Inc. PIC16LF1902/3 17.10 Timer1 Gate Control Register The Timer1 Gate Control register (T1GCON), shown in Register 17-2, is used to control Timer1 gate. REGISTER 17-2: T1GCON: TIMER1 GATE CONTROL REGISTER R/W-0/u R/W-0/u R/W-0/u R/W-0/u R/W/HC-0/u R-x/x TMR1GE T1GPOL T1GTM T1GSPM T1GGO/ DONE T1GVAL R/W-0/u R/W-0/u T1GSS bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared HC = Bit is cleared by hardware bit 7 TMR1GE: Timer1 Gate Enable bit If TMR1ON = 0: This bit is ignored If TMR1ON = 1: 1 = Timer1 counting is controlled by the Timer1 gate function 0 = Timer1 counts regardless of Timer1 gate function bit 6 T1GPOL: Timer1 Gate Polarity bit 1 = Timer1 gate is active-high (Timer1 counts when gate is high) 0 = Timer1 gate is active-low (Timer1 counts when gate is low) bit 5 T1GTM: Timer1 Gate Toggle Mode bit 1 = Timer1 Gate Toggle mode is enabled 0 = Timer1 Gate Toggle mode is disabled and toggle flip-flop is cleared Timer1 gate flip-flop toggles on every rising edge. bit 4 T1GSPM: Timer1 Gate Single-Pulse Mode bit 1 = Timer1 gate Single-Pulse mode is enabled and is controlling Timer1 gate 0 = Timer1 gate Single-Pulse mode is disabled bit 3 T1GGO/DONE: Timer1 Gate Single-Pulse Acquisition Status bit 1 = Timer1 gate single-pulse acquisition is ready, waiting for an edge 0 = Timer1 gate single-pulse acquisition has completed or has not been started bit 2 T1GVAL: Timer1 Gate Current State bit Indicates the current state of the Timer1 gate that could be provided to TMR1H:TMR1L. Unaffected by Timer1 Gate Enable (TMR1GE). bit 1-0 T1GSS: Timer1 Gate Source Select bits 00 = Timer1 gate pin 01 = Timer0 overflow output 10 = Reserved 11 = Reserved  2011-2016 Microchip Technology Inc. DS40001455F-page 131 PIC16LF1902/3 TABLE 17-5: SUMMARY OF REGISTERS ASSOCIATED WITH TIMER1 Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Register on Page INTCON GIE PEIE TMR0IE INTE IOCIE TMR0IF INTF IOCIF 60 TMR1GIE ADIE — — — — — TMR1IE 61 PIR1 TMR1GIF ADIF — — — — — TMR1IF 63 TMR1H Holding Register for the Most Significant Byte of the 16-bit TMR1 Register 126* TMR1L Holding Register for the Least Significant Byte of the 16-bit TMR1 Register 126* PIE1 TRISC TRISC7 TRISC6 T1CON TMR1CS1 TMR1CS0 T1GCON TMR1GE T1GPOL TRISC5 TRISC4 T1CKPS T1GTM T1GSPM TRISC3 TRISC2 T1OSCEN T1SYNC T1GGO/ DONE T1GVAL TRISC1 TRISC0 96 — TMR1ON 130 T1GSS1 T1GSS0 131 Legend: — = unimplemented location, read as ‘0’. Shaded cells are not used by the Timer1 module. * Page provides register information. DS40001455F-page 132  2011-2016 Microchip Technology Inc. PIC16LF1902/3 18.0 LIQUID CRYSTAL DISPLAY (LCD) DRIVER MODULE The Liquid Crystal Display (LCD) Driver module generates the timing control to drive a static or multiplexed LCD panel. In the PIC16LF1902/3 device, the module drives the panels of up to four commons and up to 72 total segments. The LCD module also provides control of the LCD pixel data. The LCD Driver module supports: • Direct driving of LCD panel • Three LCD clock sources with selectable prescaler • Up to four common pins: - Static (1 common) - 1/2 multiplex (2 commons) - 1/3 multiplex (3 commons) - 1/4 multiplex (4 commons) • 19 Segment pins • Static, 1/2 or 1/3 LCD Bias Note: 18.1 LCD Registers The module contains the following registers: • • • • • LCD Control register (LCDCON) LCD Phase register (LCDPS) LCD Reference Ladder register (LCDRL) LCD Contrast Control register (LCDCST) LCD Reference Voltage Control register (LCDREF) • Up to 3 LCD Segment Enable registers (LCDSEn) • Up to 12 LCD data registers (LCDDATAn) COM3 and SEG15 share the same physical pin on the PIC16LF1902/3, therefore SEG15 is not available when using 1/4 multiplex displays. FIGURE 18-1: LCD DRIVER MODULE BLOCK DIAGRAM Data Bus SEG(2) LCDDATAx Registers MUX To I/O Pads(1) Timing Control LCDCON LCDPS COM(3) To I/O Pads(1) LCDSEn FOSC/256 T1OSC LFINTOSC Note 1: 2: Clock Source Select and Prescaler These are not directly connected to the I/O pads, but may be tri-stated, depending on the configuration of the LCD module. COM3 and SEG15 share the same physical pin, therefore SEG15 is not available when using 1/4 multiplex displays.  2011-2016 Microchip Technology Inc. DS40001455F-page 133 PIC16LF1902/3 TABLE 18-1: LCD SEGMENT AND DATA REGISTERS # of LCD Registers Device PIC16LF1902/3 Segment Enable Data 3 12 The LCDCON register (Register 18-1) controls the operation of the LCD Driver module. The LCDPS register (Register 18-2) configures the LCD clock source prescaler and the type of waveform; Type-A or Type-B. The LCDSEn registers (Register 18-5) configure the functions of the port pins. The following LCDSEn registers are available: • LCDSE0 • LCDSE1 • LCDSE3 SE SE SE Once the module is initialized for the LCD panel, the individual bits of the LCDDATAn registers are cleared/set to represent a clear/dark pixel, respectively: • • • • • • • • • • • • LCDDATA0 LCDDATA1 LCDDATA3 LCDDATA4 LCDDATA6 LCDDATA7 LCDDATA9 LCDDATA10 LCDDATA12 LCDDATA15 LCDDATA18 LCDDATA21 SEGCOM0 SEGCOM0 SEGCOM1 SEGCOM1 SEGCOM2 SEGCOM2 SEGCOM3 SEGCOM3 SEGCOM0 SEGCOM1 SEGCOM2 SEGCOM3 As an example, Register 18-6. LCDDATAn is detailed in Once the module is configured, the LCDEN bit of the LCDCON register is used to enable or disable the LCD module. The LCD panel can also operate during Sleep by clearing the SLPEN bit of the LCDCON register. DS40001455F-page 134  2011-2016 Microchip Technology Inc. PIC16LF1902/3 REGISTER 18-1: LCDCON: LIQUID CRYSTAL DISPLAY (LCD) CONTROL REGISTER R/W-0/0 R/W-0/0 R/C-0/0 U-0 LCDEN SLPEN WERR — R/W-0/0 R/W-0/0 R/W-1/1 CS R/W-1/1 LMUX bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared C = Only clearable bit bit 7 LCDEN: LCD Driver Enable bit 1 = LCD Driver module is enabled 0 = LCD Driver module is disabled bit 6 SLPEN: LCD Driver Enable in Sleep Mode bit 1 = LCD Driver module is disabled in Sleep mode 0 = LCD Driver module is enabled in Sleep mode bit 5 WERR: LCD Write Failed Error bit 1 = LCDDATAn register written while the WA bit of the LCDPS register = 0 (must be cleared in software) 0 = No LCD write error bit 4 Unimplemented: Read as ‘0’ bit 3-2 CS: Clock Source Select bits 00 = FOSC/256 01 = T1OSC (Timer1) 1x = LFINTOSC (31 kHz) bit 1-0 LMUX: Commons Select bits Multiplex 00 Static (COM0) 19 Static 01 1/2 (COM) 38 1/2 or 1/3 10 1/3 (COM) 57 1/2 or 1/3 11 Note 1: Maximum Number of Pixels LMUX 1/4 (COM) PIC16LF1902/3 72 (1) Bias 1/3 On these devices, COM3 and SEG15 are shared on one pin, limiting the device from driving 72 segments.  2011-2016 Microchip Technology Inc. DS40001455F-page 135 PIC16LF1902/3 REGISTER 18-2: LCDPS: LCD PHASE REGISTER R/W-0/0 R/W-0/0 R-0/0 R-0/0 WFT BIASMD LCDA WA R/W-0/0 R/W-0/0 R/W-1/1 R/W-1/1 LP bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared C = Only clearable bit bit 7 WFT: Waveform Type bit 1 = Type-B phase changes on each frame boundary 0 = Type-A phase changes within each common type bit 6 BIASMD: Bias Mode Select bit When LMUX = 00: 0 = Static Bias mode (do not set this bit to ‘1’) When LMUX = 01: 1 = 1/2 Bias mode 0 = 1/3 Bias mode When LMUX = 10: 1 = 1/2 Bias mode 0 = 1/3 Bias mode When LMUX = 11: 0 = 1/3 Bias mode (do not set this bit to ‘1’) bit 5 LCDA: LCD Active Status bit 1 = LCD Driver module is active 0 = LCD Driver module is inactive bit 4 WA: LCD Write Allow Status bit 1 = Writing to the LCDDATAn registers is allowed 0 = Writing to the LCDDATAn registers is not allowed bit 3-0 LP: LCD Prescaler Selection bits 1111 = 1:16 1110 = 1:15 1101 = 1:14 1100 = 1:13 1011 = 1:12 1010 = 1:11 1001 = 1:10 1000 = 1:9 0111 = 1:8 0110 = 1:7 0101 = 1:6 0100 = 1:5 0011 = 1:4 0010 = 1:3 0001 = 1:2 0000 = 1:1 DS40001455F-page 136  2011-2016 Microchip Technology Inc. PIC16LF1902/3 REGISTER 18-3: LCDREF: LCD REFERENCE VOLTAGE CONTROL REGISTER R/W-0/0 U-0 R/W-0/0 U-0 R/W-0/0 R/W-0/0 R/W-0/0 U-0 LCDIRE — LCDIRI — VLCD3PE VLCD2PE VLCD1PE — bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared C = Only clearable bit bit 7 LCDIRE: LCD Internal Reference Enable bit 1 = Internal LCD Reference is enabled and connected to the Internal Contrast Control circuit 0 = Internal LCD Reference is disabled bit 6 Unimplemented: Read as ‘0’ bit 5 LCDIRI: LCD Internal Reference Ladder Idle Enable bit Allows the Internal FVR buffer to shut down when the LCD Reference Ladder is in power mode ‘B’ 1 = When the LCD Reference Ladder is in power mode ‘B’, the LCD Internal FVR buffer is disabled. 0 = The LCD Internal FVR Buffer ignores the LCD Reference Ladder Power mode. bit 4 Unimplemented: Read as ‘0’ bit 3 VLCD3PE: VLCD3 Pin Enable bit 1 = The VLCD3 pin is connected to the internal bias voltage LCDBIAS3(1) 0 = The VLCD3 pin is not connected bit 2 VLCD2PE: VLCD2 Pin Enable bit 1 = The VLCD2 pin is connected to the internal bias voltage LCDBIAS2(1) 0 = The VLCD2 pin is not connected bit 1 VLCD1PE: VLCD1 Pin Enable bit 1 = The VLCD1 pin is connected to the internal bias voltage LCDBIAS1(1) 0 = The VLCD1 pin is not connected bit 0 Unimplemented: Read as ‘0’ Note 1: Normal pin controls of TRISx and ANSELx are unaffected.  2011-2016 Microchip Technology Inc. DS40001455F-page 137 PIC16LF1902/3 REGISTER 18-4: LCDCST: LCD CONTRAST CONTROL REGISTER U-0 U-0 U-0 U-0 U-0 — — — — — R/W-0/0 R/W-0/0 R/W-0/0 LCDCST bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared C = Only clearable bit bit 7-3 Unimplemented: Read as ‘0’ bit 2-0 LCDCST: LCD Contrast Control bits Selects the resistance of the LCD contrast control resistor ladder Bit Value = Resistor ladder 000 = Minimum Resistance (Maximum contrast). Resistor ladder is shorted. 001 = Resistor ladder is at 1/7th of maximum resistance 010 = Resistor ladder is at 2/7th of maximum resistance 011 = Resistor ladder is at 3/7th of maximum resistance 100 = Resistor ladder is at 4/7th of maximum resistance 101 = Resistor ladder is at 5/7th of maximum resistance 110 = Resistor ladder is at 6/7th of maximum resistance 111 = Resistor ladder is at maximum resistance (Minimum contrast). DS40001455F-page 138  2011-2016 Microchip Technology Inc. PIC16LF1902/3 REGISTER 18-5: LCDSEn: LCD SEGMENT ENABLE REGISTERS R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 SEn SEn SEn SEn SEn SEn SEn SEn bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-0 SEn: Segment Enable bits 1 = Segment function of the pin is enabled 0 = I/O function of the pin is enabled REGISTER 18-6: R/W-x/u LCDDATAn: LCD DATA REGISTERS R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u R/W-x/u SEGx-COMy SEGx-COMy SEGx-COMy SEGx-COMy SEGx-COMy SEGx-COMy SEGx-COMy SEGx-COMy bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-0 SEGx-COMy: Pixel On bits 1 = Pixel on (dark) 0 = Pixel off (clear)  2011-2016 Microchip Technology Inc. DS40001455F-page 139 PIC16LF1902/3 18.2 18.2.1 LCD Clock Source Selection LCD PRESCALER A 4-bit counter is available as a prescaler for the LCD clock. The prescaler is not directly readable or writable; its value is set by the LP bits of the LCDPS register, which determine the prescaler assignment and prescale ratio. The LCD module has three possible clock sources: • FOSC/256 • T1OSC • LFINTOSC The first clock source is the system clock divided by 256 (FOSC/256). This divider ratio is chosen to provide about 1 kHz output when the system clock is 8 MHz. The divider is not programmable. Instead, the LCD prescaler bits LP of the LCDPS register are used to set the LCD frame clock rate. The prescale values are selectable from 1:1 through 1:16. The second clock source is the T1OSC. This also gives about 1 kHz when a 32.768 kHz crystal is used with the Timer1 oscillator. To use the Timer1 oscillator as a clock source, the T1OSCEN bit of the T1CON register should be set. The third clock source is the 31 kHz LFINTOSC, which provides approximately 1 kHz output. The second and third clock sources may be used to continue running the LCD while the processor is in Sleep. Using bits CS of the LCDCON register can select any of these clock sources. FOSC LCD CLOCK GENERATION ÷256 To Ladder Power Control T1OSC 32 kHz Crystal Osc. Static ÷2 1/2 4-bit Prog Prescaler ÷ 32 Counter Segment Clock ÷1, 2, 3, 4 Ring Counter 1/3, 1/4 LFINTOSC Nominal = 31 kHz LP CS DS40001455F-page 140 ÷4 COM0 COM1 COM2 COM3 FIGURE 18-2: LMUX  2011-2016 Microchip Technology Inc. PIC16LF1902/3 18.3 LCD Bias Voltage Generation The LCD module can be configured for one of three bias types: • Static Bias (2 voltage levels: VSS and VLCD) • 1/2 Bias (3 voltage levels: VSS, 1/2 VLCD and VLCD) • 1/3 Bias (4 voltage levels: VSS, 1/3 VLCD, 2/3 VLCD and VLCD) FIGURE 18-3: TABLE 18-2: LCD BIAS VOLTAGES Static Bias 1/2 Bias 1/3 Bias LCD Bias 0 VSS VSS VSS LCD Bias 1 — 1/2 VDD 1/3 VDD LCD Bias 2 — 1/2 VDD 2/3 VDD LCD Bias 3 VLCD3 VLCD3 VLCD3 So that the user is not forced to place external components and use up to three pins for bias voltage generation, internal contrast control and an internal reference ladder are provided internally to the PIC16LF1902/3. Both of these features may be used in conjunction with the external VLCD pins, to provide maximum flexibility. Refer to Figure 18-3. LCD BIAS VOLTAGE GENERATION BLOCK DIAGRAM VDD LCDIRE LCDA Power Mode Switching (LRLAP or LRLBP) 2 A 2 B 2 LCDCST VLCD3PE LCDA VLCD3 lcdbias3 VLCD2PE VLCD2 lcdbias2 BIASMD VLCD1PE VLCD1 lcdbias1 lcdbias0  2011-2016 Microchip Technology Inc. DS40001455F-page 141 PIC16LF1902/3 18.4 LCD Bias Internal Reference Ladder The internal reference ladder can be used to divide the LCD bias voltage two or three equally spaced voltages that will be supplied to the LCD segment pins. To create this, the reference ladder consists of three matched resistors. Refer to Figure 18-3. 18.4.2 POWER MODES The internal reference ladder may be operated in one of three power modes. This allows the user to trade off LCD contrast for power in the specific application. The larger the LCD glass, the more capacitance is present on a physical LCD segment, requiring more current to maintain the same contrast level. When in 1/2 Bias mode (BIASMD = 1), then the middle resistor of the ladder is shorted out so that only two voltages are generated. The current consumption of the ladder is higher in this mode, with the one resistor removed. Three different power modes are available, LP, MP and HP. The internal reference ladder can also be turned off for applications that wish to provide an external ladder or to minimize power consumption. Disabling the internal reference ladder results in all of the ladders being disconnected, allowing external voltages to be supplied. TABLE 18-3: Whenever the LCD module is inactive (LCDA = 0), the internal reference ladder will be turned off. 18.4.1 Power Mode BIAS MODE INTERACTION LCD INTERNAL LADDER POWER MODES (1/3 BIAS) Nominal Resistance of Entire Ladder Nominal IDD 3 Mohm 300 kohm 30 kohm 1 µA 10 µA 100 µA Low Medium High DS40001455F-page 142  2011-2016 Microchip Technology Inc. PIC16LF1902/3 18.4.3 AUTOMATIC POWER MODE SWITCHING The LCDRL register allows switching between two power modes, designated ‘A’ and ‘B’. ‘A’ Power mode is active for a programmable time, beginning at the time when the LCD segments transition. ‘B’ Power mode is the remaining time before the segments or commons change again. The LRLAT bits select how long, if any, that the ‘A’ Power mode is active. Refer to Figure 18-4. As an LCD segment is electrically only a capacitor, current is drawn only during the interval where the voltage is switching. To minimize total device current, the LCD internal reference ladder can be operated in a different power mode for the transition portion of the duration. This is controlled by the LCDRL Register (Register 18-7). FIGURE 18-4: To implement this, the 5-bit prescaler used to divide the 32 kHz clock down to the LCD controller’s 1 kHz base rate is used to select the power mode. LCD INTERNAL REFERENCE LADDER POWER MODE SWITCHING DIAGRAM – TYPE A Single Segment Time 32 kHz Clock Ladder Power Control ‘H00 ‘H01 ‘H02 ‘H03 ‘H04 ‘H05 ‘H06 ‘H07 ‘H0E ‘H0F ‘H00 ‘H01 Segment Clock ‘H3 LRLAT Segment Data LRLAT Power Mode Power Mode A COM0 Power Mode B Mode A V1 V0 V1 SEG0 V0 V1 COM0-SEG0 V0 -V1  2011-2016 Microchip Technology Inc. DS40001455F-page 143 LCD INTERNAL REFERENCE LADDER POWER MODE SWITCHING DIAGRAM – TYPE A WAVEFORM (1/2 MUX, 1/2 BIAS DRIVE) Single Segment Time Single Segment Time 32 kHz Clock Ladder Power Control ‘H00 ‘H01 ‘H02 ‘H03 ‘H04 ‘H05 ‘H06 ‘H07 ‘H0E ‘H0F ‘H00 ‘H01 ‘H02 ‘H03 ‘H04 ‘H05 ‘H06 ‘H07 ‘H0E ‘H0F Segment Clock Segment Data Power Mode Power Mode A LRLAT = 011 Power Mode B Power Mode A Power Mode B LRLAT = 011 V2 V1 COM0-SEG0 V0 -V1 -V2 PIC16LF1902/3 DS40001455F-page 144 FIGURE 18-5:  2011-2016 Microchip Technology Inc.  2011-2016 Microchip Technology Inc. FIGURE 18-6: LCD INTERNAL REFERENCE LADDER POWER MODE SWITCHING DIAGRAM – TYPE B WAVEFORM (1/2 MUX, 1/2 BIAS DRIVE) Single Segment Time Single Segment Time Single Segment Time Single Segment Time 32 kHz Clock Ladder Power Control ‘H00 ‘H01 ‘H02 ‘H03 ‘H0E ‘H0F ‘H10 ‘H11 ‘H12 ‘H13 ‘H1E ‘H1F ‘H00 ‘H01 ‘H02 ‘H03 ‘H0E ‘H0F ‘H10 ‘H11 ‘H12 ‘H13 ‘H1E ‘H1F Mode B Mode B Segment Clock Segment Data Power Mode Power Mode A LRLAT = 011 Power Mode B Power Mode A LRLAT = 011 Power Mode B Power Mode A LRLAT = 011 Power Power Mode A Power LRLAT = 011 V2 V1 COM0-SEG0 V0 -V1 DS40001455F-page 145 PIC16LF1902/3 -V2 PIC16LF1902/3 REGISTER 18-7: R/W-0/0 LCDRL: LCD REFERENCE LADDER CONTROL REGISTERS R/W-0/0 LRLAP R/W-0/0 R/W-0/0 LRLBP U-0 R/W-0/0 — R/W-0/0 R/W-0/0 LRLAT bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ u = Bit is unchanged x = Bit is unknown -n/n = Value at POR and BOR/Value at all other Resets ‘1’ = Bit is set ‘0’ = Bit is cleared bit 7-6 LRLAP: LCD Reference Ladder A Time Power Control bits During Time interval A (Refer toFigure 18-4): 00 = Internal LCD Reference Ladder is powered down and unconnected 01 = Internal LCD Reference Ladder is powered in Low-Power mode 10 = Internal LCD Reference Ladder is powered in Medium-Power mode 11 = Internal LCD Reference Ladder is powered in High-Power mode bit 5-4 LRLBP: LCD Reference Ladder B Time Power Control bits During Time interval B (Refer to Figure 18-4): 00 = Internal LCD Reference Ladder is powered down and unconnected 01 = Internal LCD Reference Ladder is powered in Low-Power mode 10 = Internal LCD Reference Ladder is powered in Medium-Power mode 11 = Internal LCD Reference Ladder is powered in High-Power mode bit 3 Unimplemented: Read as ‘0’ bit 2-0 LRLAT: LCD Reference Ladder A Time Interval Control bits Sets the number of 32 kHz clocks that the A Time Interval Power mode is active For type A waveforms (WFT = 0): 000 = Internal LCD Reference Ladder is always in ‘B’ Power mode 001 = Internal LCD Reference Ladder is in ‘A’ Power mode for 1 clock and ‘B’ Power mode for 15 clocks 010 = Internal LCD Reference Ladder is in ‘A’ Power mode for 2 clocks and ‘B’ Power mode for 14 clocks 011 = Internal LCD Reference Ladder is in ‘A’ Power mode for 3 clocks and ‘B’ Power mode for 13 clocks 100 = Internal LCD Reference Ladder is in ‘A’ Power mode for 4 clocks and ‘B’ Power mode for 12 clocks 101 = Internal LCD Reference Ladder is in ‘A’ Power mode for 5 clocks and ‘B’ Power mode for 11 clocks 110 = Internal LCD Reference Ladder is in ‘A’ Power mode for 6 clocks and ‘B’ Power mode for 10 clocks 111 = Internal LCD Reference Ladder is in ‘A’ Power mode for 7 clocks and ‘B’ Power mode for 9 clocks For type B waveforms (WFT = 1): 000 = Internal LCD Reference Ladder is always in ‘B’ Power mode. 001 = Internal LCD Reference Ladder is in ‘A’ Power mode for 1 clock and ‘B’ Power mode for 31 clocks 010 = Internal LCD Reference Ladder is in ‘A’ Power mode for 2 clocks and ‘B’ Power mode for 30 clocks 011 = Internal LCD Reference Ladder is in ‘A’ Power mode for 3 clocks and ‘B’ Power mode for 29 clocks 100 = Internal LCD Reference Ladder is in ‘A’ Power mode for 4 clocks and ‘B’ Power mode for 28 clocks 101 = Internal LCD Reference Ladder is in ‘A’ Power mode for 5 clocks and ‘B’ Power mode for 27 clocks 110 = Internal LCD Reference Ladder is in ‘A’ Power mode for 6 clocks and ‘B’ Power mode for 26 clocks 111 = Internal LCD Reference Ladder is in ‘A’ Power mode for 7 clocks and ‘B’ Power mode for 25 clocks DS40001455F-page 146  2011-2016 Microchip Technology Inc. PIC16LF1902/3 18.4.4 CONTRAST CONTROL The LCD contrast control circuit consists of a 7-tap resistor ladder, controlled by the LCDCST bits. Refer to Figure 18-7. FIGURE 18-7: The contrast control circuit is used to decrease the output voltage of the signal source by a total of approximately 10%, when LCDCST = 111. Whenever the LCD module is inactive (LCDA = 0), the contrast control ladder will be turned off (open). INTERNAL REFERENCE AND CONTRAST CONTROL BLOCK DIAGRAM VDD 7 Stages R R R R Analog MUX 7 To top of Reference Ladder 0 LCDCST 3 Internal Reference 18.4.5 Contrast control INTERNAL REFERENCE Under firmware control, an internal reference for the LCD bias voltages can be enabled. When enabled, the source of this voltage can be VDD. When no internal reference is selected, the LCD contrast control circuit is disabled and LCD bias must be provided externally. Whenever the LCD module is inactive (LCDA = 0), the internal reference will be turned off. When the internal reference is enabled and the Fixed Voltage Reference is selected, the LCDIRI bit can be used to minimize power consumption by tying into the LCD reference ladder automatic power mode switching. When LCDIRI = 1 and the LCD reference ladder is in Power mode ‘B’, the LCD internal FVR buffer is disables. Note: 18.4.6 VLCD PINS The VLCD pins provide the ability for an external LCD bias network to be used instead of the internal ladder. Use of the VLCD pins does not prevent use of the internal ladder. Each VLCD pin has an independent control in the LCDREF register (Register 18-3), allowing access to any or all of the LCD Bias signals. This architecture allows for maximum flexibility in different applications For example, the VLCD pins may be used to add capacitors to the internal reference ladder, increasing the drive capacity. For applications where the internal contrast control is insufficient, the firmware can choose to only enable the VLCD3 pin, allowing an external contrast control circuit to use the internal reference divider. The LCD module automatically turns on the Fixed Voltage Reference when needed.  2011-2016 Microchip Technology Inc. DS40001455F-page 147 PIC16LF1902/3 18.5 TABLE 18-5: LCD Multiplex Types The LCD driver module can be configured into one of four multiplex types: • • • • Static (only COM0 is used) 1/2 multiplex (COM are used) 1/3 multiplex (COM are used) 1/4 multiplex (COM are used) The LMUX bit setting of the LCDCON register decides which of the LCD common pins are used (see Table 18-4 for details). If the pin is a digital I/O, the corresponding TRIS bit controls the data direction. If the pin is a COM drive, then the TRIS setting of that pin is overridden. TABLE 18-4: LMUX COM3 COM2 COM1 COM1 Static 00 Unused Unused Unused Active 1/2 01 Unused Unused Active Active 1/3 10 Unused Active Active Active 1/4 11 Active Active Active Active 18.6 Multiplex Frame Frequency(2) = Static Clock source(1)/(4 x (LCD Prescaler) x 32 x 1)) 1/2 Clock source(1)/(2 x (LCD Prescaler) x 32 x 2)) 1/3 Clock source(1)/(1 x (LCD Prescaler) x 32 x 3)) 1/4 Clock source(1)/(1 x (LCD Prescaler) x 32 x 4)) Note 1: 2: Segment Enables Clock source LFINTOSC. is FOSC/256, T1OSC or See Figure 18-2. TABLE 18-6: COMMON PIN USAGE Multiplex FRAME FREQUENCY FORMULAS APPROXIMATE FRAME FREQUENCY (IN Hz) USING FOSC @ 8 MHz, TIMER1 @ 32.768 kHz OR LFINTOSC LP Static 1/2 1/3 1/4 2 122 122 162 122 3 81 81 108 81 4 61 61 81 61 5 49 49 65 49 6 41 41 54 41 7 35 35 47 35 The LCDSEn registers are used to select the pin function for each segment pin. The selection allows each pin to operate as either an LCD segment driver or as one of the pin’s alternate functions. To configure the pin as a segment pin, the corresponding bits in the LCDSEn registers must be set to ‘1’. If the pin is a digital I/O, the corresponding TRIS bit controls the data direction. Any bit set in the LCDSEn registers overrides any bit settings in the corresponding TRIS register. Note: 18.7 On a Power-on Reset, these pins are configured as normal I/O, not LCD pins. Pixel Control The LCDDATAx registers contain bits which define the state of each pixel. Each bit defines one unique pixel. Register 18-6 shows the correlation of each bit in the LCDDATAx registers to the respective common and segment signals. Any LCD pixel location not being used for display can be used as general purpose RAM. 18.8 LCD Frame Frequency The rate at which the COM and SEG outputs change is called the LCD frame frequency. DS40001455F-page 148  2011-2016 Microchip Technology Inc. PIC16LF1902/3 18.9 LCD Waveform Generation LCD waveforms are generated so that the net AC voltage across the dark pixel should be maximized and the net AC voltage across the clear pixel should be minimized. The net DC voltage across any pixel should be zero. The COM signal represents the time slice for each common, while the SEG contains the pixel data. The pixel signal (COM-SEG) will have no DC component and it can take only one of the two RMS values. The higher RMS value will create a dark pixel and a lower RMS value will create a clear pixel. As the number of commons increases, the delta between the two RMS values decreases. The delta represents the maximum contrast that the display can have. The LCDs can be driven by two types of waveform: Type-A and Type-B. In Type-A waveform, the phase changes within each common type, whereas in Type-B waveform, the phase changes on each frame boundary. Thus, Type-A waveform maintains 0 VDC over a single frame, whereas Type-B waveform takes two frames. Note 1: If Sleep has to be executed with LCD Sleep disabled (LCDCON is ‘1’), then care must be taken to execute Sleep only when VDC on all the pixels is ‘0’. 2: When the LCD clock source is FOSC/256, if Sleep is executed, irrespective of the LCDCON setting, the LCD immediately goes into Sleep. Thus, take care to see that VDC on all pixels is ‘0’ when Sleep is executed. Figure 18-8 through Figure 18-18 provide waveforms for static, half-multiplex, 1/3-multiplex and 1/4-multiplex drives for Type-A and Type-B waveforms. FIGURE 18-8: TYPE-A/TYPE-B WAVEFORMS IN STATIC DRIVE V1 COM0 pin V0 COM0 V1 SEG0 pin V0 V1 SEG1 pin V0 V1 V0 SEG1 SEG0 SEG2 SEG7 SEG6 SEG5 SEG4 SEG3 COM0-SEG0 segment voltage (active) COM0-SEG1 segment voltage (inactive)  2011-2016 Microchip Technology Inc. -V1 V0 1 Frame DS40001455F-page 149 PIC16LF1902/3 FIGURE 18-9: TYPE-A WAVEFORMS IN 1/2 MUX, 1/2 BIAS DRIVE V2 COM0 pin COM1 V1 V0 V2 COM1 pin COM0 V1 V0 V2 V1 SEG0 pin V0 V2 V1 SEG1 pin V2 SEG0 SEG1 SEG2 SEG3 V0 V1 V0 COM0-SEG0 segment voltage (active) -V1 -V2 V2 V1 V0 COM0-SEG1 segment voltage (inactive) -V1 -V2 1 Frame 1 Segment Time Note: 1 Frame = 2 single segment times. DS40001455F-page 150  2011-2016 Microchip Technology Inc. PIC16LF1902/3 FIGURE 18-10: TYPE-B WAVEFORMS IN 1/2 MUX, 1/2 BIAS DRIVE V2 COM1 V1 COM0 pin V0 COM0 V2 COM1 pin V1 V0 V2 SEG0 pin V1 SEG1 SEG0 SEG2 SEG3 V0 V2 SEG1 pin V1 V0 V2 V1 V0 COM0-SEG0 segment voltage (active) -V1 -V2 V2 V1 V0 COM0-SEG1 segment voltage (inactive) -V1 2 Frames -V2 1 Segment Time Note: 1 Frame = 2 single segment times.  2011-2016 Microchip Technology Inc. DS40001455F-page 151 PIC16LF1902/3 FIGURE 18-11: TYPE-A WAVEFORMS IN 1/2 MUX, 1/3 BIAS DRIVE V3 COM1 V2 COM0 pin V1 V0 V3 COM0 V2 COM1 pin V1 V0 V3 V2 SEG0 pin V1 V0 SEG1 SEG0 SEG2 SEG3 V3 V2 SEG1 pin V1 V0 V3 V2 V1 V0 COM0-SEG0 segment voltage (active) -V1 -V2 -V3 V3 V2 V1 V0 COM0-SEG1 segment voltage (inactive) -V1 -V2 1 Frame -V3 1 Segment Time Note: 1 Frame = 2 single segment times. DS40001455F-page 152  2011-2016 Microchip Technology Inc. PIC16LF1902/3 FIGURE 18-12: TYPE-B WAVEFORMS IN 1/2 MUX, 1/3 BIAS DRIVE V3 COM1 V2 COM0 pin V1 V0 V3 COM0 V2 COM1 pin V1 V0 V3 V2 SEG0 pin V1 V0 SEG1 SEG0 SEG2 SEG3 V3 V2 SEG1 pin V1 V0 V3 V2 V1 V0 COM0-SEG0 segment voltage (active) -V1 -V2 -V3 V3 V2 V1 V0 COM0-SEG1 segment voltage (inactive) -V1 2 Frames -V2 -V3 1 Segment Time Note: 1 Frame = 2 single segment times.  2011-2016 Microchip Technology Inc. DS40001455F-page 153 PIC16LF1902/3 FIGURE 18-13: TYPE-A WAVEFORMS IN 1/3 MUX, 1/2 BIAS DRIVE V2 COM0 pin V1 V0 V2 COM2 COM1 pin V1 V0 COM1 V2 COM0 COM2 pin V1 V0 V2 SEG0 and SEG2 pins V1 V0 V2 V1 V0 SEG0 SEG1 SEG2 SEG1 pin V2 V1 V0 COM0-SEG0 segment voltage (inactive) -V1 -V2 V2 V1 V0 COM0-SEG1 segment voltage (active) -V1 -V2 1 Frame 1 Segment Time Note: DS40001455F-page 154 1 Frame = 2 single segment times.  2011-2016 Microchip Technology Inc. PIC16LF1902/3 FIGURE 18-14: TYPE-B WAVEFORMS IN 1/3 MUX, 1/2 BIAS DRIVE V2 COM0 pin V1 V0 COM2 V2 COM1 pin V1 COM1 V0 COM0 V2 COM2 pin V1 V0 V2 V1 V0 SEG0 SEG1 SEG2 SEG0 pin V2 SEG1 pin V1 V0 V2 V1 V0 COM0-SEG0 segment voltage (inactive) -V1 -V2 V2 V1 V0 COM0-SEG1 segment voltage (active) -V1 -V2 2 Frames 1 Segment Time Note: 1 Frame = 2 single segment times.  2011-2016 Microchip Technology Inc. DS40001455F-page 155 PIC16LF1902/3 FIGURE 18-15: TYPE-A WAVEFORMS IN 1/3 MUX, 1/3 BIAS DRIVE V3 V2 COM0 pin V1 V0 V3 COM2 V2 COM1 pin V1 COM1 V0 COM0 V3 V2 COM2 pin V1 V0 V3 V2 V1 V0 SEG0 SEG1 SEG2 SEG0 and SEG2 pins V3 V2 SEG1 pin V1 V0 V3 V2 V1 V0 COM0-SEG0 segment voltage (inactive) -V1 -V2 -V3 V3 V2 V1 V0 COM0-SEG1 segment voltage (active) -V1 -V2 -V3 1 Frame 1 Segment Time Note: DS40001455F-page 156 1 Frame = 2 single segment times.  2011-2016 Microchip Technology Inc. PIC16LF1902/3 FIGURE 18-16: TYPE-B WAVEFORMS IN 1/3 MUX, 1/3 BIAS DRIVE V3 V2 COM0 pin V1 V0 V3 COM2 V2 COM1 pin V1 COM1 V0 COM0 V3 V2 COM2 pin V1 V0 V3 V2 V1 V0 SEG0 SEG1 SEG2 SEG0 pin V3 V2 SEG1 pin V1 V0 V3 V2 V1 V0 COM0-SEG0 segment voltage (inactive) -V1 -V2 -V3 V3 V2 V1 V0 COM0-SEG1 segment voltage (active) -V1 -V2 -V3 2 Frames 1 Segment Time Note: 1 Frame = 2 single segment times.  2011-2016 Microchip Technology Inc. DS40001455F-page 157 PIC16LF1902/3 FIGURE 18-17: TYPE-A WAVEFORMS IN 1/4 MUX, 1/3 BIAS DRIVE COM3 COM2 COM1 COM0 pin V3 V2 V1 V0 COM1 pin V3 V2 V1 V0 COM2 pin V3 V2 V1 V0 COM3 pin V3 V2 V1 V0 SEG0 pin V3 V2 V1 V0 SEG1 pin V3 V2 V1 V0 SEG0 SEG1 COM0 V3 V2 V1 V0 -V1 -V2 -V3 COM0-SEG0 segment voltage (active) COM0-SEG1 segment voltage (inactive) 1 Frame V3 V2 V1 V0 -V1 -V2 -V3 1 Segment Time Note: 1 Frame = 2 single segment times. DS40001455F-page 158  2011-2016 Microchip Technology Inc. PIC16LF1902/3 FIGURE 18-18: TYPE-B WAVEFORMS IN 1/4 MUX, 1/3 BIAS DRIVE COM3 COM0 pin V3 V2 V1 V0 COM1 pin V3 V2 V1 V0 COM2 pin V3 V2 V1 V0 COM3 pin V3 V2 V1 V0 SEG0 pin V3 V2 V1 V0 SEG1 pin V3 V2 V1 V0 COM2 COM1 SEG0 SEG1 COM0 V3 V2 V1 V0 -V1 -V2 -V3 COM0-SEG0 segment voltage (active) COM0-SEG1 segment voltage (inactive) 2 Frames V3 V2 V1 V0 -V1 -V2 -V3 1 Segment Time Note: 1 Frame = 2 single segment times.  2011-2016 Microchip Technology Inc. DS40001455F-page 159 PIC16LF1902/3 18.10 LCD Interrupts The LCD module provides an interrupt in two cases. An interrupt when the LCD controller goes from active to inactive controller. An interrupt also provides unframe boundaries for Type B waveform. The LCD timing generation provides an interrupt that defines the LCD frame timing. 18.10.1 LCD INTERRUPT ON MODULE SHUTDOWN An LCD interrupt is generated when the module completes shutting down (LCDA goes from ‘1’ to ‘0’). 18.10.2 LCD FRAME INTERRUPTS A new frame is defined to begin at the leading edge of the COM0 common signal. The interrupt will be set immediately after the LCD controller completes accessing all pixel data required for a frame. This will occur at a fixed interval before the frame boundary (TFINT), as shown in Figure 18-19. The LCD controller will begin to access data for the next frame within the interval from the interrupt to when the controller begins to access data after the interrupt (TFWR). New data must be written within TFWR, as this is when the LCD controller will begin to access the data for the next frame. When the LCD driver is running with Type-B waveforms and the LMUX bits are not equal to ‘00’ (static drive), there are some additional issues that must be addressed. Since the DC voltage on the pixel takes two frames to maintain zero volts, the pixel data must not change between subsequent frames. If the pixel data were allowed to change, the waveform for the odd frames would not necessarily be the complement of the waveform generated in the even frames and a DC component would be introduced into the panel. Therefore, when using Type-B waveforms, the user must synchronize the LCD pixel updates to occur within a subframe after the frame interrupt. To correctly sequence writing while in Type-B, the interrupt will only occur on complete phase intervals. If the user attempts to write when the write is disabled, the WERR bit of the LCDCON register is set and the write does not occur. Note: The LCD frame interrupt is not generated when the Type-A waveform is selected and when the Type-B with no multiplex (static) is selected. DS40001455F-page 160  2011-2016 Microchip Technology Inc. PIC16LF1902/3 FIGURE 18-19: WAVEFORMS AND INTERRUPT TIMING IN QUARTER-DUTY CYCLE DRIVE (EXAMPLE – TYPE-B, NON-STATIC) LCD Interrupt Occurs Controller Accesses Next Frame Data COM0 V3 V2 V1 V0 COM1 V3 V2 V1 V0 COM2 V3 V2 V1 V0 V3 V2 V1 V0 COM3 2 Frames TFINT Frame Boundary Frame Boundary TFWR Frame Boundary TFWR = TFRAME/2*(LMUX + 1) + TCY/2 TFINT = (TFWR/2 – (2 TCY + 40 ns))  minimum = 1.5(TFRAME/4) – (2 TCY + 40 ns) (TFWR/2 – (1 TCY + 40 ns))  maximum = 1.5(TFRAME/4) – (1 TCY + 40 ns)  2011-2016 Microchip Technology Inc. DS40001455F-page 161 PIC16LF1902/3 18.11 Operation During Sleep The LCD module can operate during Sleep. The selection is controlled by bit SLPEN of the LCDCON register. Setting the SLPEN bit allows the LCD module to go to Sleep. Clearing the SLPEN bit allows the module to continue to operate during Sleep. If a SLEEP instruction is executed and SLPEN = 1, the LCD module will cease all functions and go into a very low-current Consumption mode. The module will stop operation immediately and drive the minimum LCD voltage on both segment and common lines. Figure 18-20 shows this operation. The LCD module can be configured to operate during Sleep. The selection is controlled by bit SLPEN of the LCDCON register. Clearing SLPEN and correctly configuring the LCD module clock will allow the LCD module to operate during Sleep. Setting SLPEN and correctly executing the LCD module shutdown will disable the LCD module during Sleep and save power. If a SLEEP instruction is executed and SLPEN = 1, the LCD module will immediately cease all functions, drive the outputs to Vss and go into a very low-current mode. The SLEEP instruction should only be executed after the LCD module has been disabled and the current cycle completed, thus ensuring that there are no DC voltages on the glass. To disable the LCD module, clear the LCDEN bit. The LCD module will complete the disabling process after the current frame, clear the LCDA bit and optionally cause an interrupt. The steps required to properly enter Sleep with the LCD disabled are: • Clear LCDEN • Wait for LCDA = 0 either by polling or by interrupt • Execute SLEEP If SLPEN = 0 and SLEEP is executed while the LCD module clock source is FOSC/4, then the LCD module will halt with the pin driving the last LCD voltage pattern. Prolonged exposure to a fixed LCD voltage pattern will cause damage to the LCD glass. To prevent LCD glass damage, either perform the proper LCD module shutdown prior to Sleep, or change the LCD module clock to allow the LCD module to continue operation during Sleep. If a SLEEP instruction is executed and SLPEN = 0 and the LCD module clock is either T1OSC or LFINTOSC, the module will continue to display the current contents of the LCDDATA registers. While in Sleep, the LCD data cannot be changed. If the LCDIE bit is set, the device will wake from Sleep on the next LCD frame boundary. The LCD module current consumption will not decrease in this mode; however, the overall device power consumption will be lower due to the shutdown of the CPU and other peripherals. DS40001455F-page 162 Table 18-7 shows the status of the LCD module during a Sleep while using each of the three available clock sources. Note: When the LCDEN bit is cleared, the LCD module will be disabled at the completion of frame. At this time, the port pins will revert to digital functionality. To minimize power consumption due to floating digital inputs, the LCD pins should be driven low using the PORT and TRIS registers. If a SLEEP instruction is executed and SLPEN = 0, the module will continue to display the current contents of the LCDDATA registers. To allow the module to continue operation while in Sleep, the clock source must be either the LFINTOSC or T1OSC external oscillator. While in Sleep, the LCD data cannot be changed. The LCD module current consumption will not decrease in this mode; however, the overall consumption of the device will be lower due to shut down of the core and other peripheral functions. Table 18-7 shows the status of the LCD module during Sleep while using each of the three available clock sources: TABLE 18-7: Clock Source T1OSC LCD MODULE STATUS DURING SLEEP SLPEN Operational During Sleep 0 Yes 1 No LFINTOSC 0 Yes 1 No FOSC/4 0 No 1 No Note: The LFINTOSC or external T1OSC oscillator must be used to operate the LCD module during Sleep. If LCD interrupts are being generated (Type-B waveform with a multiplex mode not static) and LCDIE = 1, the device will awaken from Sleep on the next frame boundary.  2011-2016 Microchip Technology Inc. PIC16LF1902/3 FIGURE 18-20: SLEEP ENTRY/EXIT WHEN SLPEN = 1 V3 V2 V1 COM0 V0 V3 V2 V1 V0 COM1 V3 V2 V1 V0 COM2 V3 V2 V1 V0 SEG0 2 Frames SLEEP Instruction Execution  2011-2016 Microchip Technology Inc. Wake-up DS40001455F-page 163 PIC16LF1902/3 18.12 Configuring the LCD Module 18.14 LCD Current Consumption The following is the sequence of steps to configure the LCD module. When using the LCD module the current consumption consists of the following three factors: 1. • Oscillator Selection • LCD Bias Source • Capacitance of the LCD segments 2. 3. 4. 5. 6. 7. Select the frame clock prescale using bits LP of the LCDPS register. Configure the appropriate pins to function as segment drivers using the LCDSEn registers. Configure the LCD module for the following using the LCDCON register: - Multiplex and Bias mode, bits LMUX - Timing source, bits CS - Sleep mode, bit SLPEN Write initial values to pixel data registers, LCDDATA0 through LCDDATA21. Clear LCD Interrupt Flag, LCDIF bit of the PIR2 register and if desired, enable the interrupt by setting bit LCDIE of the PIE2 register. Configure bias voltages by setting the LCDRL, LCDREF and the associated ANSELx registers as needed. Enable the LCD module by setting bit LCDEN of the LCDCON register. 18.13 Disabling the LCD Module To disable the LCD module, write all ‘0’s to the LCDCON register. DS40001455F-page 164 The current consumption of just the LCD module can be considered negligible compared to these other factors. 18.14.1 OSCILLATOR SELECTION The current consumed by the clock source selected must be considered when using the LCD module. See Section 21.0 “Electrical Specifications” for oscillator current consumption information. 18.14.2 LCD BIAS SOURCE The LCD bias source, internal or external, can contribute significantly to the current consumption. Use the highest possible resistor values while maintaining contrast to minimize current. 18.14.3 CAPACITANCE OF THE LCD SEGMENTS The LCD segments which can be modeled as capacitors which must be both charged and discharged every frame. The size of the LCD segment and its technology determines the segment’s capacitance.  2011-2016 Microchip Technology Inc. PIC16LF1902/3 TABLE 18-8: Name SUMMARY OF REGISTERS ASSOCIATED WITH LCD OPERATION Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 INTF IOCIF INTCON GIE PEIE TMR0IE INTE IOCIE TMR0IF LCDCON LCDEN SLPEN WERR — CS1 CS0 LMUX 60 135 — — — — — LCDDATA0 SEG7 COM0 SEG6 COM0 SEG5 COM0 SEG4 COM0 SEG3 COM0 SEG2 COM0 SEG1 COM0 SEG0 COM0 139 LCDDATA1 SEG15 COM0 SEG14 COM0 SEG13 COM0 SEG12 COM0 SEG11 COM0 SEG10 COM0 SEG9 COM0 SEG8 COM0 139 LCDDATA3 SEG7 COM1 SEG6 COM1 SEG5 COM1 SEG4 COM1 SEG3 COM1 SEG2 COM1 SEG1 COM1 SEG0 COM1 139 LCDDATA4 SEG15 COM1 SEG14 COM1 SEG13 COM1 SEG12 COM1 SEG11 COM1 SEG10 COM1 SEG9 COM1 SEG8 COM1 139 LCDDATA6 SEG7 COM2 SEG6 COM2 SEG5 COM2 SEG4 COM2 SEG3 COM2 SEG2 COM2 SEG1 COM2 SEG0 COM2 139 LCDDATA7 SEG15 COM2 SEG14 COM2 SEG13 COM2 SEG12 COM2 SEG11 COM2 SEG10 COM2 SEG9 COM2 SEG8 COM2 139 LCDDATA9 SEG7 COM3 SEG6 COM3 SEG5 COM3 SEG4 COM3 SEG3 COM3 SEG2 COM3 SEG1 COM3 SEG0 COM3 139 LCDDATA10 SEG15 COM3 SEG14 COM3 SEG13 COM3 SEG12 COM3 SEG11 COM3 SEG10 COM3 SEG9 COM3 SEG8 COM3 139 LCDDATA12 — — — — — SEG26 COM0 SEG25 COM0 SEG24 COM0 139 LCDDATA15 — — — — — SEG26 COM1 SEG25 COM1 SEG24 COM1 139 LCDDATA18 — — — — — SEG26 COM2 SEG25 COM2 SEG24 COM2 139 LCDDATA21 — — — — — SEG26 COM3 SEG25 COM3 SEG24 COM3 139 WFT BIASMD LCDA WA LCDIRE — LCDIRI — LCDCST LCDPS LCDREF LCDRL LRLAP LRLBP LCDCST Register on Page 138 LP VLCD3PE VLCD2PE — 136 VLCD1PE — LRLAT 137 146 LCDSE0 SE 139 LCDSE1 SE 139 LCDSE3 — — — — — PIE2 — — — — — — — — — — PIR2 T1CON Legend: TMR1CS1 TMR1CS0 T1CKPS1 T1CKPS0 T1OSCEN SE 139 LCDIE — — 62 LCDIF — — 64 T1SYNC — TMR1ON 130 — = unimplemented location, read as ‘0’. Shaded cells are not used by the LCD module.  2011-2016 Microchip Technology Inc. DS40001455F-page 165 PIC16LF1902/3 19.0 IN-CIRCUIT SERIAL PROGRAMMING™ (ICSP™) 19.2 Low-Voltage Programming Entry Mode ICSP™ programming allows customers to manufacture circuit boards with unprogrammed devices. Programming can be done after the assembly process allowing the device to be programmed with the most recent firmware or a custom firmware. Five pins are needed for ICSP™ programming: • ICSPCLK • ICSPDAT • MCLR/VPP • VDD • VSS The Low-Voltage Programming Entry mode allows the PIC® Flash MCUs to be programmed using VDD only, without high voltage. When the LVP bit of Configuration Word 2 is set to ‘1’, the low-voltage ICSP programming entry is enabled. To disable the Low-Voltage ICSP mode, the LVP bit must be programmed to ‘0’. In Program/Verify mode the Program Memory, User IDs and the Configuration Words are programmed through serial communications. The ICSPDAT pin is a bidirectional I/O used for transferring the serial data and the ICSPCLK pin is the clock input. For more information on ICSP™ refer to the “PIC16F193X/LF193X/PIC16F194X/LF194X/PIC16LF 190X Memory Programming Specification” (DS41397). Once the key sequence is complete, MCLR must be held at VIL for as long as Program/Verify mode is to be maintained. 19.1 High-Voltage Programming Entry Mode The device is placed into High-Voltage Programming Entry mode by holding the ICSPCLK and ICSPDAT pins low then raising the voltage on MCLR/VPP to VIHH. Entry into the Low-Voltage Programming Entry mode requires the following steps: 1. 2. MCLR is brought to VIL. A 32-bit key sequence is presented on ICSPDAT, while clocking ICSPCLK. If low-voltage programming is enabled (LVP = 1), the MCLR Reset function is automatically enabled and cannot be disabled. See Section 5.3 “Low-Power Brown-out Reset (LPBOR)” for more information. The LVP bit can only be reprogrammed to ‘0’ by using the High-Voltage Programming mode. 19.3 Common Programming Interfaces Connection to a target device is typically done through an ICSP™ header. A commonly found connector on development tools is the RJ-11 in the 6P6C (6-pin, 6 connector) configuration. See Figure 19-1. FIGURE 19-1: VDD ICD RJ-11 STYLE CONNECTOR INTERFACE ICSPDAT NC 2 4 6 ICSPCLK 1 3 5 Target VPP/MCLR VSS PC Board Bottom Side Pin Description* 1 = VPP/MCLR 2 = VDD Target 3 = VSS (ground) 4 = ICSPDAT 5 = ICSPCLK 6 = No Connect DS40001455F-page 166  2011-2016 Microchip Technology Inc. PIC16LF1902/3 Another connector often found in use with the PICkit™ programmers is a standard 6-pin header with 0.1 inch spacing. Refer to Figure 19-2. FIGURE 19-2: PICkit™ STYLE CONNECTOR INTERFACE Pin 1 Indicator Pin Description* 1 2 3 4 5 6 1 = VPP/MCLR 2 = VDD Target 3 = VSS (ground) 4 = ICSPDAT 5 = ICSPCLK 6 = No Connect * The 6-pin header (0.100" spacing) accepts 0.025" square pins.  2011-2016 Microchip Technology Inc. DS40001455F-page 167 PIC16LF1902/3 For additional interface recommendations, refer to your specific device programmer manual prior to PCB design. It is recommended that isolation devices be used to separate the programming pins from other circuitry. The type of isolation is highly dependent on the specific application and may include devices such as resistors, diodes, or even jumpers. See Figure 19-3 for more information. FIGURE 19-3: TYPICAL CONNECTION FOR ICSP™ PROGRAMMING External Programming Signals Device to be Programmed VDD VDD VDD VPP MCLR/VPP VSS VSS Data ICSPDAT Clock ICSPCLK * * * To Normal Connections * Isolation devices (as required). DS40001455F-page 168  2011-2016 Microchip Technology Inc. PIC16LF1902/3 20.0 INSTRUCTION SET SUMMARY 20.1 Read-Modify-Write Operations • Byte Oriented • Bit Oriented • Literal and Control Any instruction that specifies a file register as part of the instruction performs a Read-Modify-Write (R-M-W) operation. The register is read, the data is modified, and the result is stored according to either the instruction, or the destination designator ‘d’. A read operation is performed on a register even if the instruction writes to that register. The literal and control category contains the most varied instruction word format. TABLE 20-1: Each PIC16 instruction is a 14-bit word containing the operation code (opcode) and all required operands. The opcodes are broken into three broad categories. Table 20-3 lists the instructions recognized by the MPASMTM assembler. All instructions are executed within a single instruction cycle, with the following exceptions, which may take two or three cycles: • Subroutine takes two cycles (CALL, CALLW) • Returns from interrupts or subroutines take two cycles (RETURN, RETLW, RETFIE) • Program branching takes two cycles (GOTO, BRA, BRW, BTFSS, BTFSC, DECFSZ, INCSFZ) • One additional instruction cycle will be used when any instruction references an indirect file register and the file select register is pointing to program memory. One instruction cycle consists of four oscillator cycles; for an oscillator frequency of 4 MHz, this gives a nominal instruction execution rate of 1 MHz. All instruction examples use the format ‘0xhh’ to represent a hexadecimal number, where ‘h’ signifies a hexadecimal digit. OPCODE FIELD DESCRIPTIONS Field f Description Register file address (0x00 to 0x7F) W Working register (accumulator) b Bit address within an 8-bit file register k Literal field, constant data or label x Don’t care location (= 0 or 1). The assembler will generate code with x = 0. It is the recommended form of use for compatibility with all Microchip software tools. d Destination select; d = 0: store result in W, d = 1: store result in file register f. Default is d = 1. n FSR or INDF number. (0-1) mm Pre-post increment-decrement mode selection TABLE 20-2: ABBREVIATION DESCRIPTIONS Field Program Counter TO Time-out bit C DC Z PD  2011-2016 Microchip Technology Inc. Description PC Carry bit Digit carry bit Zero bit Power-down bit DS40001455F-page 169 PIC16LF1902/3 FIGURE 20-1: GENERAL FORMAT FOR INSTRUCTIONS Byte-oriented file register operations 13 8 7 6 OPCODE d f (FILE #) 0 d = 0 for destination W d = 1 for destination f f = 7-bit file register address Bit-oriented file register operations 13 10 9 7 6 OPCODE b (BIT #) f (FILE #) 0 b = 3-bit bit address f = 7-bit file register address Literal and control operations General 13 OPCODE 8 7 0 k (literal) k = 8-bit immediate value CALL and GOTO instructions only 13 11 10 OPCODE 0 k (literal) k = 11-bit immediate value MOVLP instruction only 13 OPCODE 7 6 0 k (literal) k = 7-bit immediate value MOVLB instruction only 13 OPCODE 5 4 0 k (literal) k = 5-bit immediate value BRA instruction only 13 OPCODE 9 8 0 k (literal) k = 9-bit immediate value FSR Offset instructions 13 OPCODE 7 6 n 5 0 k (literal) n = appropriate FSR k = 6-bit immediate value FSR Increment instructions 13 OPCODE 3 2 1 0 n m (mode) n = appropriate FSR m = 2-bit mode value OPCODE only 13 0 OPCODE DS40001455F-page 170  2011-2016 Microchip Technology Inc. PIC16LF1902/3 TABLE 20-3: PIC16LF1902/3 ENHANCED INSTRUCTION SET 14-Bit Opcode Mnemonic, Operands Description Cycles MSb LSb Status Affected Notes BYTE-ORIENTED FILE REGISTER OPERATIONS ADDWF ADDWFC ANDWF ASRF LSLF LSRF CLRF CLRW COMF DECF INCF IORWF MOVF MOVWF RLF RRF SUBWF SUBWFB SWAPF XORWF f, d f, d f, d f, d f, d f, d f – f, d f, d f, d f, d f, d f f, d f, d f, d f, d f, d f, d Add W and f Add with Carry W and f AND W with f Arithmetic Right Shift Logical Left Shift Logical Right Shift Clear f Clear W Complement f Decrement f Increment f Inclusive OR W with f Move f Move W to f Rotate Left f through Carry Rotate Right f through Carry Subtract W from f Subtract with Borrow W from f Swap nibbles in f Exclusive OR W with f 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 00 11 00 11 11 11 00 00 00 00 00 00 00 00 00 00 00 11 00 00 0111 1101 0101 0111 0101 0110 0001 0001 1001 0011 1010 0100 1000 0000 1101 1100 0010 1011 1110 0110 dfff dfff dfff dfff dfff dfff lfff 0000 dfff dfff dfff dfff dfff 1fff dfff dfff dfff dfff dfff dfff ffff ffff ffff ffff ffff ffff ffff 00xx ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff C, DC, Z C, DC, Z Z C, Z C, Z C, Z Z Z Z Z Z Z Z C C C, DC, Z C, DC, Z Z 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 BYTE ORIENTED SKIP OPERATIONS DECFSZ INCFSZ f, d f, d Decrement f, Skip if 0 Increment f, Skip if 0 BCF BSF f, b f, b Bit Clear f Bit Set f 1(2) 1(2) 00 00 1, 2 1, 2 1011 dfff ffff 1111 dfff ffff BIT-ORIENTED FILE REGISTER OPERATIONS 1 1 01 01 00bb bfff ffff 01bb bfff ffff 2 2 1, 2 1, 2 BIT-ORIENTED SKIP OPERATIONS BTFSC BTFSS f, b f, b Bit Test f, Skip if Clear Bit Test f, Skip if Set 1 (2) 1 (2) 01 01 10bb bfff ffff 11bb bfff ffff 1 1 1 1 1 1 1 1 11 11 11 00 11 11 11 11 1110 1001 1000 0000 0001 0000 1100 1010 LITERAL OPERATIONS ADDLW ANDLW IORLW MOVLB MOVLP MOVLW SUBLW XORLW k k k k k k k k Add literal and W AND literal with W Inclusive OR literal with W Move literal to BSR Move literal to PCLATH Move literal to W Subtract W from literal Exclusive OR literal with W kkkk kkkk kkkk 001k 1kkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk C, DC, Z Z Z C, DC, Z Z Note 1: If the Program Counter (PC) is modified, or a conditional test is true, the instruction requires two cycles. The second cycle is executed as a NOP. 2: If this instruction addresses an INDF register and the MSb of the corresponding FSR is set, this instruction will require one additional instruction cycle.  2011-2016 Microchip Technology Inc. DS40001455F-page 171 PIC16LF1902/3 TABLE 20-3: PIC16LF1902/3 ENHANCED INSTRUCTION SET (CONTINUED) 14-Bit Opcode Mnemonic, Operands Description Cycles MSb LSb Status Affected Notes CONTROL OPERATIONS 2 2 2 2 2 2 2 2 BRA BRW CALL CALLW GOTO RETFIE RETLW RETURN k – k – k k k – Relative Branch Relative Branch with W Call Subroutine Call Subroutine with W Go to address Return from interrupt Return with literal in W Return from Subroutine CLRWDT NOP OPTION RESET SLEEP TRIS – – – – – f Clear Watchdog Timer No Operation Load OPTION_REG register with W Software device Reset Go into Standby mode Load TRIS register with W ADDFSR MOVIW n, k n mm MOVWI k[n] n mm Add Literal k to FSRn Move Indirect FSRn to W with pre/post inc/dec modifier, mm Move INDFn to W, Indexed Indirect. Move W to Indirect FSRn with pre/post inc/dec modifier, mm Move W to INDFn, Indexed Indirect. 11 00 10 00 10 00 11 00 001k 0000 0kkk 0000 1kkk 0000 0100 0000 kkkk 0000 kkkk 0000 kkkk 0000 kkkk 0000 kkkk 1011 kkkk 1010 kkkk 1001 kkkk 1000 00 00 00 00 00 00 0000 0000 0000 0000 0000 0000 0110 0000 0110 0000 0110 0110 0100 TO, PD 0000 0010 0001 0011 TO, PD 0fff INHERENT OPERATIONS 1 1 1 1 1 1 C-COMPILER OPTIMIZED k[n] 1 1 11 00 0001 0nkk kkkk 0000 0001 0nmm Z 2, 3 1 1 11 00 1111 0nkk kkkk Z 0000 0001 1nmm 2 2, 3 1 11 1111 1nkk kkkk 2 Note 1: If the Program Counter (PC) is modified, or a conditional test is true, the instruction requires two cycles. The second cycle is executed as a NOP. 2: If this instruction addresses an INDF register and the MSb of the corresponding FSR is set, this instruction will require one additional instruction cycle. 3: See Table in the MOVIW and MOVWI instruction descriptions. DS40001455F-page 172  2011-2016 Microchip Technology Inc. PIC16LF1902/3 20.2 Instruction Descriptions ADDFSR Add Literal to FSRn ANDLW AND literal with W Syntax: [ label ] ADDFSR FSRn, k Syntax: [ label ] ANDLW Operands: -32  k  31 n  [ 0, 1] Operands: 0  k  255 Operation: FSR(n) + k  FSR(n) Status Affected: None Description: The signed 6-bit literal ‘k’ is added to the contents of the FSRnH:FSRnL register pair. k Operation: (W) .AND. (k)  (W) Status Affected: Z Description: The contents of W register are AND’ed with the 8-bit literal ‘k’. The result is placed in the W register. FSRn is limited to the range 0000h FFFFh. Moving beyond these bounds will cause the FSR to wrap-around. ADDLW Add literal and W ANDWF AND W with f Syntax: [ label ] ADDLW Syntax: [ label ] ANDWF Operands: 0  f  127 d 0,1 Operation: (W) .AND. (f)  (destination) Status Affected: Z Description: AND the W register with register ‘f’. If ‘d’ is ‘0’, the result is stored in the W register. If ‘d’ is ‘1’, the result is stored back in register ‘f’. ASRF Arithmetic Right Shift k Operands: 0  k  255 Operation: (W) + k  (W) Status Affected: C, DC, Z Description: The contents of the W register are added to the 8-bit literal ‘k’ and the result is placed in the W register. f,d ADDWF Add W and f Syntax: [ label ] ADDWF Syntax: [ label ] ASRF Operands: 0  f  127 d 0,1 Operands: 0  f  127 d [0,1] Operation: (W) + (f)  (destination) Operation: (f) dest (f)  dest, (f)  C, f,d Status Affected: C, DC, Z Description: Add the contents of the W register with register ‘f’. If ‘d’ is ‘0’, the result is stored in the W register. If ‘d’ is ‘1’, the result is stored back in register ‘f’. ADDWFC ADD W and CARRY bit to f Syntax: [ label ] ADDWFC Operands: 0  f  127 d [0,1] Status Affected: C, Z Description: The contents of register ‘f’ are shifted one bit to the right through the Carry flag. The MSb remains unchanged. If ‘d’ is ‘0’, the result is placed in W. If ‘d’ is ‘1’, the result is stored back in register ‘f’. register f C f {,d} Operation: (W) + (f) + (C)  dest Status Affected: C, DC, Z Description: Add W, the Carry flag and data memory location ‘f’. If ‘d’ is ‘0’, the result is placed in W. If ‘d’ is ‘1’, the result is placed in data memory location ‘f’.  2011-2016 Microchip Technology Inc. f {,d} DS40001455F-page 173 PIC16LF1902/3 BCF Bit Clear f Syntax: [ label ] BCF f,b BTFSC Bit Test f, Skip if Clear Syntax: [ label ] BTFSC f,b 0  f  127 0b7 Operands: 0  f  127 0b7 Operands: Operation: 0  (f) Operation: skip if (f) = 0 Status Affected: None Status Affected: None Description: Bit ‘b’ in register ‘f’ is cleared. Description: If bit ‘b’ in register ‘f’ is ‘1’, the next instruction is executed. If bit ‘b’, in register ‘f’, is ‘0’, the next instruction is discarded, and a NOP is executed instead, making this a 2-cycle instruction. BRA Relative Branch BTFSS Bit Test f, Skip if Set Syntax: [ label ] BRA label [ label ] BRA $+k Syntax: [ label ] BTFSS f,b Operands: Operands: -256  label - PC + 1  255 -256  k  255 0  f  127 0b VDD)20 mA Maximum output current sunk by any I/O pin.............................................................................................................................. 50 mA sourced by any I/O pin......................................................................................................................... 50 mA Power dissipation is calculated as follows: PDIS = VDD x {IDD –  IOH} +  {(VDD – VOH) x IOH} + (VOl x IOL). Note 1: † NOTICE: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at those or any other conditions above those indicated in the operation listings of this specification is not implied. Exposure above maximum rating conditions for extended periods may affect device reliability. 21.1 Standard Operating Conditions The standard operating conditions for any device are defined as: Operating Voltage: Operating Temperature: VDDMIN VDD VDDMAX TA_MIN TA TA_MAX VDD — Operating Supply Voltage(2) VDDMIN (Fosc  16 MHz) ......................................................................................................... +1.8V VDDMIN (Fosc  20 MHz) ......................................................................................................... +2.3V VDDMAX .................................................................................................................................... +3.6V TA — Operating Ambient Temperature Range Industrial Temperature TA_MIN ...................................................................................................................................... -40°C TA_MAX .................................................................................................................................... +85°C Extended Temperature TA_MIN ...................................................................................................................................... -40°C TA_MAX .................................................................................................................................. +125°C Note 1: 2: Maximum current rating requires even load distribution across I/O pins. Maximum current rating may be limited by the device package power dissipation characterizations, see Table 21-6: “Thermal Characteristics” to calculate device specifications. See Parameter D001, DS Characteristics: Supply Voltage.  2011-2016 Microchip Technology Inc. DS40001455F-page 183 PIC16LF1902/3 VOLTAGE FREQUENCY GRAPH, -40°C  TA +125°C VDD (V) FIGURE 21-1: 3.6 EC Mode Only 2.5 Internal Oscillator or EC Mode 2.3 2.0 1.8 0 10 4 20 16 Frequency (MHz) Note 1: The shaded region indicates the permissible combinations of voltage and frequency. 2: Refer to Table 21-7 for each Oscillator mode’s supported frequencies. FIGURE 21-2: HFINTOSC FREQUENCY ACCURACY OVER DEVICE VDD AND TEMPERATURE 125 - 15% to + 12.5% Temperature (°C) 85 60 ± 8% 25 ± 6.5% 0 -20 -40 1.8 - 15% to + 12.5% 2.0 2.5 3.0 3.5 3.6 VDD (V) DS40001455F-page 184  2011-2016 Microchip Technology Inc. PIC16LF1902/3 21.2 DC Characteristics TABLE 21-1: SUPPLY VOLTAGE Standard Operating Conditions (unless otherwise stated) PIC16LF1902/3 Param. No. D001 Sym. VDD Characteristic Supply Voltage Min. Typ† Max. Units Conditions 1.8 — 3.6 V FOSC  16 MHz 2.3 — 3.6 V FOSC  20 MHz (EC mode) Device in Sleep mode D002* VDR RAM Data Retention Voltage(1) 1.5 — — V D002A* VPOR* Power-on Reset Release Voltage 1.54 1.64 1.74 V D002B* VPORR* Power-on Reset Rearm Voltage — 1.7 — V Device in Sleep mode D003 VADFVR Fixed Voltage Reference Voltage for ADC, Initial Accuracy 6 7 7 8 — — — — 4 4 6 6 % 1.024V, VDD  1.8V, 85°C 1.024V, VDD  1.8V, 125°C 2.048V, VDD  2.5V, 85°C 2.048V, VDD  2.5V, 125°C D003A VCDAFVR Fixed Voltage Reference Voltage for Comparator and DAC, Initial Accuracy 7 8 8 9 — — — — 5 5 7 7 % 1.024V, VDD  1.8V, 85°C 1.024V, VDD  1.8V, 125°C 2.048V, VDD  2.5V, 85°C 2.048V, VDD  2.5V, 125°C D003B VLCDFVR Fixed Voltage Reference Voltage for LCD Bias, Initial Accuracy 9 9.5 — — 9 9 % 3.072V, VDD  3.6V, 85°C 3.072V, VDD  3.6V, 125°C D003C* TCVFVR Temperature Coefficient, Fixed Voltage Reference — -130 — ppm/°C D003D* VFVR/ VIN Line Regulation, Fixed Voltage Reference — 0.270 — %/V D004* SVDD VDD Rise Rate to ensure internal Power-on Reset signal 0.05 — — V/ms See Section 5.1 “Power-on Reset (POR)” for details. * These parameters are characterized but not tested. † Data in “Typ” column is at 3.3V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. Note 1: This is the limit to which VDD can be lowered in Sleep mode without losing RAM data. FIGURE 21-3: POR AND POR REARM WITH SLOW RISING VDD VDD VPOR VPORR VSS NPOR POR REARM VSS TVLOW(2) Note 1: 2: 3: TPOR(3) When NPOR is low, the device is held in Reset. TPOR 1 s typical. TVLOW 2.7 s typical.  2011-2016 Microchip Technology Inc. DS40001455F-page 185 PIC16LF1902/3 TABLE 21-2: SUPPLY CURRENT (IDD)(1,2) Standard Operating Conditions (unless otherwise stated) PIC16LF1902/3 Param. No. Device Characteristics D010 D011 D012 D013 D014 D015 D016 D017 D017A D018 D018A † Note 1: 2: 3: Conditions Min. Typ† Max. Units VDD — 58 75 A 1.8 — 115 140 A 3.0 — 133 176 A 3.6 — 130 200 A 1.8 — 245 300 A 3.0 — 290 350 A 3.6 — 218 275 A 1.8 — 283 375 A 3.0 — 314 395 A 3.6 — 233 325 A 1.8 — 309 425 A 3.0 — 347 475 A 3.6 — 305 360 A 1.8 — 433 520 A 3.0 — 500 600 A 3.6 — 395 480 A 1.8 — 600 720 A 3.0 — 700 850 A 3.6 — 567 670 A 1.8 — 915 1100 A 3.0 — 1087 1300 A 3.6 — 2.7 7.2 A 1.8 — 4.5 9.7 A 3.0 — 5.2 12.0 A 3.6 — 2.7 6.5 A 1.8 — 4.5 9.0 A 3.0 — 5.2 11.0 A 3.6 — 2.4 6.7 A 1.8 — 4.2 9.2 A 3.0 — 4.8 11.5 A 3.6 — 2.4 6.0 A 1.8 — 4.2 8.5 A 3.0 — 4.8 10.5 A 3.6 Note FOSC = 1 MHz EC Oscillator mode High-Power mode FOSC = 4 MHz EC Oscillator mode High-Power mode FOSC = 500 kHz HFINTOSC mode FOSC = 1 MHz HFINTOSC mode FOSC = 4 MHz HFINTOSC mode FOSC = 8 MHz HFINTOSC mode FOSC = 16 MHz HFINTOSC mode FOSC = 31 kHz LFINTOSC mode -40°C  TA  +125°C FOSC = 31 kHz LFINTOSC mode -40°C  TA  +85°C FOSC = 32 kHz EC Oscillator mode, Low-Power mode -40°C  TA  +125°C FOSC = 32 kHz EC Oscillator mode, Low-Power mode -40°C  TA  +85°C Data in “Typ” column is at 3.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. The test conditions for all IDD measurements in active operation mode are: OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD; MCLR = VDD; WDT disabled. The supply current is mainly a function of the operating voltage and frequency. Other factors, such as I/O pin loading and switching rate, oscillator type, internal code execution pattern and temperature, also have an impact on the current consumption. FVR and BOR are disabled. DS40001455F-page 186  2011-2016 Microchip Technology Inc. PIC16LF1902/3 TABLE 21-3: POWER-DOWN CURRENTS (IPD) Standard Operating Conditions (unless otherwise stated) PIC16LF1902 Param. No. Device Characteristics Min. Power-down Base Current (IPD) D023 D024 D025 D026 D027 D028 D029 D030 D031 Typ† Conditions Max. +85°C Max. +125°C Units VDD Note WDT, BOR, FVR and T1OSC disabled, all Peripherals Inactive (2) — 0.15 1.0 3.0 A 1.8 — 0.16 2.0 4.0 A 3.0 — 0.65 3.0 5.0 A 3.6 — 0.27 2.0 4.0 A 1.8 — 0.56 3.0 5.0 A 3.0 — 0.75 4.0 6.0 A 3.6 — 17.5 31 35 A 1.8 — 17.7 33 38 A 3.0 — 17.8 35 41 A 3.6 — 0.15 2.3 3.56 A 3.0 — 0.21 3.4 4.70 A 3.6 — 7.0 10 12 A 3.0 — 7.5 12 14 A 3.6 — 0.50 2.0 4.0 A 1.8 — 0.60 3.0 5.0 A 3.0 — 0.70 4.0 6.0 A 3.6 — 0.40 2.0 4.0 A 1.8 — 0.70 3.0 5.0 A 3.0 — 0.90 4.0 6.0 A 3.6 — — 250 — A 1.8 — — 250 — A 3.0 — — 250 — A 3.6 WDT Current (Note 1) FVR current LPBOR current BOR Current T1OSC Current ADC Current (Note 1, Note 3), no conversion in progress ADC Current (Note 1, Note 3), conversion in progress LCD Bias Ladder † Legend: Note 1: 2: 3: Low power — 1 2 6 A 1.8 Medium Power — 10 13 21 A 3.0 High Power — 100 111 120 A 3.6 Data in “Typ” column is at 3.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. TBD = To Be Determined The peripheral current is the sum of the base IDD or IPD and the additional current consumed when this peripheral is enabled. The peripheral  current can be determined by subtracting the base IDD or IPD current from this limit. Max values should be used when calculating total current consumption. The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD. A/D oscillator source is FRC.  2011-2016 Microchip Technology Inc. DS40001455F-page 187 PIC16LF1902/3 TABLE 21-4: I/O PORTS DC CHARACTERISTICS Param No. Sym. VIL Characteristic Standard Operating Conditions (unless otherwise stated) Min. Typ† Max. Units Conditions Input Low Voltage I/O PORT: D032 with TTL buffer — — 0.15 VDD V 1.8V  VDD  3.6V D033 with Schmitt Trigger buffer — — 0.2 VDD V 1.8V  VDD  3.6V — — 0.2 VDD V 0.25 VDD + 0.8 — — V 1.8V  VDD  3.6V 1.8V  VDD  3.6V D034 MCLR, OSC1 VIH Input High Voltage I/O ports: D040 with TTL buffer D041 with Schmitt Trigger buffer D042 MCLR IIL 0.8 VDD — — V 0.8 VDD — — V nA Input Leakage Current(2) D060 I/O ports — ±5 ± 125 ±5 ± 1000 nA VSS  VPIN  VDD, Pin at high-impedance @ 85°C 125°C D061 MCLR(3) — ± 50 ± 200 nA VSS  VPIN  VDD @ 85°C 25 100 200 A VDD = 3.3V, VPIN = VSS — 0.6 V IOL = 6mA, VDD = 3.3V IOL = 1.8mA, VDD = 1.8V — — V IOH = 3mA, VDD = 3.3V IOH = 1mA, VDD = 1.8V — 50 pF IPUR Weak Pull-up Current VOL Output Low Voltage D070* D080 I/O ports — VOH D090 Output High Voltage I/O ports VDD - 0.7 Capacitive Loading Specs on Output Pins D101* CIO All I/O pins — * † These parameters are characterized but not tested. Data in “Typ” column is at 3.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. Note 1: Negative current is defined as current sourced by the pin. DS40001455F-page 188  2011-2016 Microchip Technology Inc. PIC16LF1902/3 TABLE 21-5: MEMORY PROGRAMMING REQUIREMENTS DC CHARACTERISTICS Param. No. Sym. Standard Operating Conditions (unless otherwise stated) Characteristic Min. Typ† Max. Units Conditions Program Memory High Voltage Programming Specifications D110 VIHH Voltage on MCLR/VPP/RE3 pin 8.0 — 9.0 V D111 IDDVPP Programming/Erase Current on VPP, High Voltage Programming — — 10 mA VDD for Bulk Erase 2.7 — VDD max. V VDD min. — VDD max. V — 1.0 mA 5.0 mA D112 D113 VPEW VDD for Write or Row Erase D114 IPPPGM Programming/Erase Current on VPP, Low Voltage Programming — D115 IDDPGM Programming/Erase Current on VDD, High or Low Voltage Programming — D121 EP Cell Endurance D122 VPR VDD for Read D123 TIW D124 TRETD (Note 2) Program Flash Memory † Note 1: 2: 1K 10K — E/W VDD min. — VDD max. V Self-timed Write Cycle Time — 2 2.5 ms Characteristic Retention 40 — — Year -40C to +85C (Note 1) Provided no other specifications are violated Data in “Typ” column is at 3.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. Self-write and Block Erase. Required only if single-supply programming is disabled. TABLE 21-6: THERMAL CONSIDERATIONS Standard Operating Conditions (unless otherwise stated) Param. No. TH01 TH02 Sym. Characteristic JA Thermal Resistance Junction to Ambient JC TH03 TJMAX TH04 PD TH05 Thermal Resistance Junction to Case Maximum Junction Temperature Power Dissipation PINTERNAL Internal Power Dissipation Typ. Units Conditions 60 C/W 28-pin SPDIP package 80 C/W 28-pin SOIC package 90 C/W 28-pin SSOP package 27.5 C/W 28-pin UQFN 4x4mm package 31.4 C/W 28-pin SPDIP package 24 C/W 28-pin SOIC package 24 C/W 28-pin SSOP package 24 C/W 28-pin UQFN 4x4mm package 150 C — W PD = PINTERNAL + PI/O — W PINTERNAL = IDD x VDD(1) TH06 PI/O I/O Power Dissipation — W PI/O =  (IOL * VOL) +  (IOH * (VDD - VOH)) TH07 PDER Derated Power — W PDER = PDMAX (TJ - TA)/JA(2) Note 1: IDD is current to run the chip alone without driving any load on the output pins. 2: TA = Ambient Temperature 3: TJ = Junction Temperature  2011-2016 Microchip Technology Inc. DS40001455F-page 189 PIC16LF1902/3 21.3 AC Characteristics The timing parameter symbols have been created with one of the following formats: 1. TppS2ppS 2. TppS T F Frequency Lowercase letters (pp) and their meanings: pp cc CCP1 ck CLKOUT cs CS di SDI do SDO dt Data in io I/O PORT mc MCLR Uppercase letters and their meanings: S F Fall H High I Invalid (High-Impedance) L Low FIGURE 21-4: T Time osc rd rw sc ss t0 t1 wr OSC1 RD RD or WR SCK SS T0CKI T1CKI WR P R V Z Period Rise Valid High-Impedance LOAD CONDITIONS Load Condition Pin CL VSS Legend: CL = 50 pF for all pins, 15 pF for OSC2 output DS40001455F-page 190  2011-2016 Microchip Technology Inc. PIC16LF1902/3 TABLE 21-7: CLOCK OSCILLATOR TIMING REQUIREMENTS Standard Operating Conditions (unless otherwise stated) Param. No. OS01 Sym. FOSC OS02 OS03 Characteristic External CLKIN Frequency(1) Min. Typ† Max. Units Conditions DC — 0.5 MHz External Clock (ECL) DC — 4 MHz External Clock (ECM) DC — 20 MHz External Clock (ECH) TOSC External CLKIN Period(1) 50 —  ns External Clock (EC) TCY Instruction Cycle Time(1) 200 TCY DC ns TCY = 4/FOSC * † These parameters are characterized but not tested. Data in “Typ” column is at 3.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. Note 1: Instruction cycle period (TCY) equals four times the input oscillator time base period. All specified values are based on characterization data for that particular oscillator type under standard operating conditions with the device executing code. Exceeding these specified limits may result in an unstable oscillator operation and/or higher than expected current consumption. All devices are tested to operate at “min” values with an external clock applied to CLKIN pin. When an external clock input is used, the “max” cycle time limit is “DC” (no clock) for all devices. TABLE 21-8: OSCILLATOR PARAMETERS Standard Operating Conditions (unless otherwise stated) Param. No. OS08 Sym. HFOSC Characteristic Internal Calibrated HFINTOSC Frequency(2) OS10A* TIOSC ST HFINTOSC 16 MHz Oscillator Wake-up from Sleep Start-up Time Freq. Tolerance Min. Typ† Max. Units Conditions 8% 6.5% — — 16 16 — — MHz MHz 0°C  TA  +85°C VDD = 3.0V at +25°C — — 5 15 s VDD = 2.0V, -40°C to +85°C — — 5 15 s VDD = 3.0V, -40°C to +85°C * † These parameters are characterized but not tested. Data in “Typ” column is at 3.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. Note 1: Instruction cycle period (TCY) equals four times the input oscillator time base period. All specified values are based on characterization data for that particular oscillator type under standard operating conditions with the device executing code. Exceeding these specified limits may result in an unstable oscillator operation and/or higher than expected current consumption. All devices are tested to operate at “min” values with an external clock applied to the OSC1 pin. When an external clock input is used, the “max” cycle time limit is “DC” (no clock) for all devices. 2: To ensure these oscillator frequency tolerances, VDD and VSS must be capacitively decoupled as close to the device as possible. 0.1 F and 0.01 F values in parallel are recommended.  2011-2016 Microchip Technology Inc. DS40001455F-page 191 PIC16LF1902/3 FIGURE 21-5: CLKOUT AND I/O TIMING Cycle Write Fetch Read Execute Q4 Q1 Q2 Q3 FOSC OS12 OS11 OS20 OS21 CLKOUT OS19 OS18 OS16 OS13 OS17 I/O pin (Input) OS14 OS15 I/O pin (Output) New Value Old Value OS18, OS19 TABLE 21-9: CLKOUT AND I/O TIMING PARAMETERS Standard Operating Conditions (unless otherwise stated) Param No. Sym. Characteristic FOSC to CLKOUT (1) OS11 TosH2ckL OS12 TosH2ckH FOSC to CLKOUT OS13 TckL2ioV (1) CLKOUT to Port out valid (1) (1) OS14 OS15 OS16 TioV2ckH TosH2ioV TosH2ioI OS17 TioV2osH OS18 TioR Port input valid before CLKOUT FOSC (Q1 cycle) to Port out valid FOSC (Q2 cycle) to Port input invalid (I/O in hold time) Port input valid to FOSC(Q2 cycle) (I/O in setup time) Port output rise time OS19 TioF Port output fall time OS20* Tinp OS21* Tioc Min. Typ† Max. Units — — 70 ns VDD = 3.0V — — 72 ns VDD = 3.0V — — 20 ns TOSC + 200 ns — 50 — 50 — — 70* — ns ns ns 20 — — ns — — — — 25 25 40 15 28 15 — — 72 32 55 30 — — ns INT pin input high or low time Interrupt-on-change new input level time * These parameters are characterized but not tested. † Data in “Typ” column is at 3.0V, 25C unless otherwise stated. Note 1: Measurements are taken in EC mode where CLKOUT output is 4 x TOSC. DS40001455F-page 192 ns Conditions VDD = 3.0V VDD = 3.0V VDD = 3.0V VDD = 2.0V VDD = 2.0V VDD = 3.0V ns ns  2011-2016 Microchip Technology Inc. PIC16LF1902/3 FIGURE 21-6: RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER AND POWER-UP TIMER TIMING VDD MCLR 30 Internal POR 33 PWRT Time-out 32 OSC Start-Up Time Internal Reset(1) Watchdog Timer Reset(1) 31 34 34 I/O pins Note 1: Asserted low. FIGURE 21-7: BROWN-OUT RESET TIMING AND CHARACTERISTICS VDD VBOR and VHYST VBOR (Device in Brown-out Reset) (Device not in Brown-out Reset) 37 Reset (due to BOR) 33(1) Note 1: 64 ms delay only if PWRTE bit in the Configuration Word register is programmed to ‘0’. 2 ms delay if PWRTE = 0 and VREGEN = 1.  2011-2016 Microchip Technology Inc. DS40001455F-page 193 PIC16LF1902/3 FIGURE 21-8: MINIMUM PULSE WIDTH FOR LPBOR DETECTION VDD (Monitored Voltage) VLPBOR VBPW < 10 nVs Pulse Rejected DS40001455F-page 194 10 nVs < VBPW < 500 nVs 500 nVs < VBPW Maybe Detected  2011-2016 Microchip Technology Inc. PIC16LF1902/3 TABLE 21-10: RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER, POWER-UP TIMER AND BROWN-OUT RESET PARAMETERS Standard Operating Conditions (unless otherwise stated) Param. No. Sym. Characteristic Min. Typ† Max. Units Conditions 30 TMCL MCLR Pulse Width (low) 2 5 — — — — s s 31 FWDTLP Low Frequency Internal Oscillator Frequency 19 33 52 kHz 32 TOST Oscillator Start-up Timer Period(1) — 1024 — Tosc (Note 2) 33* TPWRT Power-up Timer Period, PWRTE = 0 — 2048 — Tosc Clocked by LFINTOSC 34* TIOZ I/O High-Impedance from MCLR Low or Watchdog Timer Reset — — 2.0 s 35 VBOR Brown-out Reset Voltage: BORV = 0 2.55 BORV = 1 1.80 2.70 1.90 2.85 2.05 V V 35A* VHYST Brown-out Reset Hysteresis 25 — 50 — 75 100 mV mV -40°C to +85°C -40°C to +125°C 35B* TBORDC Brown-out Reset DC Response Time 1 — 3 — 5 10 s s VDD  VBOR, -40°C to +85°C VDD  VBOR 35C TBORAC Brown-out Reset AC Response Time — 100 — ns Transient Response immunity for a noise spike that goes from VDD to VSS and back with 10 ns rise and fall times. Guidance only. 36 TFVRS — — 5 s Turn on to specified stability 37 VLPBOR Low-Power Brown-out Reset Voltage 1.85 1.95 2.10 V -40°C to +85°C 38* VZPHYST Zero-Power Brown-out Reset Hysteresis 0 25 60 mV -40°C to +85°C 39* TZPBPW Zero-Power Brown-out Reset AC Response Time for BOR detection 10 — 500 nVs VDD  VBOR, -40°C to +85°C Fixed Voltage Reference Turn-on Time VDD = 3.0V, -40°C to +85°C VDD = 3.0V * † These parameters are characterized but not tested. Data in “Typ” column is at 3.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. Note 1: Instruction cycle period (TCY) equals four times the input oscillator time base period. All specified values are based on characterization data for that particular oscillator type under standard operating conditions with the device executing code. Exceeding these specified limits may result in an unstable oscillator operation and/or higher than expected current consumption. All devices are tested to operate at “min” values with an external clock applied to the OSC1 pin. When an external clock input is used, the “max” cycle time limit is “DC” (no clock) for all devices. 2: Period of the slower clock. 3: To ensure these voltage tolerances, VDD and VSS must be capacitively decoupled as close to the device as possible. 0.1 F and 0.01 F values in parallel are recommended.  2011-2016 Microchip Technology Inc. DS40001455F-page 195 PIC16LF1902/3 FIGURE 21-9: TIMER0 AND TIMER1 EXTERNAL CLOCK TIMINGS T0CKI 40 41 42 T1CKI 45 46 49 47 TMR0 or TMR1 TABLE 21-11: TIMER0 AND TIMER1 EXTERNAL CLOCK REQUIREMENTS Standard Operating Conditions(unless otherwise stated) Param No. 40* Sym. TT0H Characteristic T0CKI High Pulse Width Min. No Prescaler With Prescaler 41* TT0L T0CKI Low Pulse Width No Prescaler With Prescaler 42* TT0P T0CKI Period 45* TT1H T1CKI High Synchronous, No Prescaler Time Synchronous, with Prescaler Asynchronous TT1L 46* T1CKI Low Time Max. Units 0.5 TCY + 20 — — ns 10 — — ns 0.5 TCY + 20 — — ns 10 — — ns Greater of: 20 or TCY + 40 N — — ns 0.5 TCY + 20 — — ns 15 — — ns 30 — — ns Synchronous, No Prescaler 0.5 TCY + 20 — — ns Synchronous, with Prescaler 15 — — ns Asynchronous 30 — — ns Greater of: 30 or TCY + 40 N — — ns 47* TT1P T1CKI Input Synchronous Period 48 FT1 Timer1 Oscillator Input Frequency Range (oscillator enabled by setting bit T1OSCEN) 49* TCKEZTMR1 Delay from External Clock Edge to Timer Increment Asynchronous * † Typ† 60 — — ns 32.4 32.768 33.1 kHz 2 TOSC — 7 TOSC — Conditions N = prescale value (2, 4, ..., 256) N = prescale value (1, 2, 4, 8) Timers in Sync mode These parameters are characterized but not tested. Data in “Typ” column is at 3.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. DS40001455F-page 196  2011-2016 Microchip Technology Inc. PIC16LF1902/3 TABLE 21-12: PIC16LF1902/3 CONVERTER (ADC) CHARACTERISTICS(1,2,3) Operating Conditions (unless otherwise stated) VDD = 3.0V, TA = 25°C Param. Sym. No. Characteristic Min. Typ† Max. Units Conditions AD01 NR Resolution — — 10 AD02 EIL Integral Error — ±1 ±1.7 bit AD03 EDL Differential Error — ±1 ±1 AD04 EOFF Offset Error — ±1 ±2.5 LSb VREF = 3.0V AD05 EGN Gain Error — ±1 ±2.0 LSb VREF = 3.0V AD06 VREF Reference Voltage 1.8 — VDD V AD07 VAIN Full-Scale Range VSS — VREF V AD08 ZAIN Recommended Impedance of Analog Voltage Source — — 10 k LSb VREF = 3.0V LSb No missing codes VREF = 3.0V VREF = (VRPOS - VRNEG) Can go higher if external 0.01F capacitor is present on input pin. * † These parameters are characterized but not tested. Data in “Typ” column is at 3.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. Note 1:Total Absolute Error includes integral, differential, offset and gain errors. 2: The ADC conversion result never decreases with an increase in the input voltage and has no missing codes. 3: See Section 22.0 “DC and AC Characteristics Graphs and Charts” for operating characterization. TABLE 21-13: PIC16LF1902/3 A/D CONVERSION REQUIREMENTS Standard Operating Conditions (unless otherwise stated) Param. Sym. No. AD130* TAD AD131 TCNV Characteristic Min. Typ† Max. Units ADC Clock Period (TADC) 1.0 — 6.0 ADC Internal FRC Oscillator Period (TFRC) 1.0 2.0 6.0 s ADCS = x11 (ADC FRC mode) Conversion Time (not including Acquisition Time)(1) — 11 — TAD Set GO/DONE bit to conversion complete s AD132* TACQ Acquisition Time — 5.0 — AD133* THCD Holding Capacitor Disconnect Time — — 1/2 TAD 1/2 TAD + 1TCY — — s Conditions FOSC-based FOSC-based ADCS = x11 (ADC FRC mode) * † These parameters are characterized but not tested. Data in “Typ” column is at 3.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. Note 1: The ADRES register may be read on the following TCY cycle.  2011-2016 Microchip Technology Inc. DS40001455F-page 197 PIC16LF1902/3 FIGURE 21-10: PIC16LF1902/3 A/D CONVERSION TIMING (NORMAL MODE) BSF ADCON0, GO AD134 1 TCY (TOSC/2(1)) AD131 Q4 AD130 A/D CLK 7 A/D Data 6 5 4 3 2 1 0 NEW_DATA OLD_DATA ADRES 1 TCY ADIF GO Sample DONE Sampling Stopped AD132 Note 1: If the A/D clock source is selected as RC, a time of TCY is added before the A/D clock starts. This allows the SLEEP instruction to be executed. FIGURE 21-11: PIC16LF1902/3 A/D CONVERSION TIMING (SLEEP MODE) BSF ADCON0, GO AD134 (TOSC/2 + TCY(1)) 1 TCY AD131 Q4 AD130 A/D CLK 7 A/D Data 6 5 4 OLD_DATA ADRES 3 2 1 0 NEW_DATA ADIF 1 TCY GO DONE Sample AD132 Sampling Stopped Note 1: If the A/D clock source is selected as RC, a time of TCY is added before the A/D clock starts. This allows the SLEEP instruction to be executed. DS40001455F-page 198  2011-2016 Microchip Technology Inc. PIC16LF1902/3 22.0 DC AND AC CHARACTERISTICS GRAPHS AND CHARTS Graphs and charts are not available at this time.  2011-2016 Microchip Technology Inc. DS40001455F-page 199 PIC16LF1902/3 23.0 DEVELOPMENT SUPPORT The PIC® microcontrollers (MCU) and dsPIC® digital signal controllers (DSC) are supported with a full range of software and hardware development tools: • Integrated Development Environment - MPLAB® X IDE Software • Compilers/Assemblers/Linkers - MPLAB XC Compiler - MPASMTM Assembler - MPLINKTM Object Linker/ MPLIBTM Object Librarian - MPLAB Assembler/Linker/Librarian for Various Device Families • Simulators - MPLAB X SIM Software Simulator • Emulators - MPLAB REAL ICE™ In-Circuit Emulator • In-Circuit Debuggers/Programmers - MPLAB ICD 3 - PICkit™ 3 • Device Programmers - MPLAB PM3 Device Programmer • Low-Cost Demonstration/Development Boards, Evaluation Kits and Starter Kits • Third-party development tools 23.1 MPLAB X Integrated Development Environment Software The MPLAB X IDE is a single, unified graphical user interface for Microchip and third-party software, and hardware development tool that runs on Windows®, Linux and Mac OS® X. Based on the NetBeans IDE, MPLAB X IDE is an entirely new IDE with a host of free software components and plug-ins for highperformance application development and debugging. Moving between tools and upgrading from software simulators to hardware debugging and programming tools is simple with the seamless user interface. With complete project management, visual call graphs, a configurable watch window and a feature-rich editor that includes code completion and context menus, MPLAB X IDE is flexible and friendly enough for new users. With the ability to support multiple tools on multiple projects with simultaneous debugging, MPLAB X IDE is also suitable for the needs of experienced users. Feature-Rich Editor: • Color syntax highlighting • Smart code completion makes suggestions and provides hints as you type • Automatic code formatting based on user-defined rules • Live parsing User-Friendly, Customizable Interface: • Fully customizable interface: toolbars, toolbar buttons, windows, window placement, etc. • Call graph window Project-Based Workspaces: • • • • Multiple projects Multiple tools Multiple configurations Simultaneous debugging sessions File History and Bug Tracking: • Local file history feature • Built-in support for Bugzilla issue tracker DS40001455F-page 200  2011-2016 Microchip Technology Inc. PIC16LF1902/3 23.2 MPLAB XC Compilers The MPLAB XC Compilers are complete ANSI C compilers for all of Microchip’s 8, 16, and 32-bit MCU and DSC devices. These compilers provide powerful integration capabilities, superior code optimization and ease of use. MPLAB XC Compilers run on Windows, Linux or MAC OS X. For easy source level debugging, the compilers provide debug information that is optimized to the MPLAB X IDE. The free MPLAB XC Compiler editions support all devices and commands, with no time or memory restrictions, and offer sufficient code optimization for most applications. MPLAB XC Compilers include an assembler, linker and utilities. The assembler generates relocatable object files that can then be archived or linked with other relocatable object files and archives to create an executable file. MPLAB XC Compiler uses the assembler to produce its object file. Notable features of the assembler include: • • • • • • Support for the entire device instruction set Support for fixed-point and floating-point data Command-line interface Rich directive set Flexible macro language MPLAB X IDE compatibility 23.3 MPASM Assembler The MPASM Assembler is a full-featured, universal macro assembler for PIC10/12/16/18 MCUs. The MPASM Assembler generates relocatable object files for the MPLINK Object Linker, Intel® standard HEX files, MAP files to detail memory usage and symbol reference, absolute LST files that contain source lines and generated machine code, and COFF files for debugging. The MPASM Assembler features include: 23.4 MPLINK Object Linker/ MPLIB Object Librarian The MPLINK Object Linker combines relocatable objects created by the MPASM Assembler. It can link relocatable objects from precompiled libraries, using directives from a linker script. The MPLIB Object Librarian manages the creation and modification of library files of precompiled code. When a routine from a library is called from a source file, only the modules that contain that routine will be linked in with the application. This allows large libraries to be used efficiently in many different applications. The object linker/library features include: • Efficient linking of single libraries instead of many smaller files • Enhanced code maintainability by grouping related modules together • Flexible creation of libraries with easy module listing, replacement, deletion and extraction 23.5 MPLAB Assembler, Linker and Librarian for Various Device Families MPLAB Assembler produces relocatable machine code from symbolic assembly language for PIC24, PIC32 and dsPIC DSC devices. MPLAB XC Compiler uses the assembler to produce its object file. The assembler generates relocatable object files that can then be archived or linked with other relocatable object files and archives to create an executable file. Notable features of the assembler include: • • • • • • Support for the entire device instruction set Support for fixed-point and floating-point data Command-line interface Rich directive set Flexible macro language MPLAB X IDE compatibility • Integration into MPLAB X IDE projects • User-defined macros to streamline assembly code • Conditional assembly for multipurpose source files • Directives that allow complete control over the assembly process  2011-2016 Microchip Technology Inc. DS40001455F-page 201 PIC16LF1902/3 23.6 MPLAB X SIM Software Simulator The MPLAB X SIM Software Simulator allows code development in a PC-hosted environment by simulating the PIC MCUs and dsPIC DSCs on an instruction level. On any given instruction, the data areas can be examined or modified and stimuli can be applied from a comprehensive stimulus controller. Registers can be logged to files for further run-time analysis. The trace buffer and logic analyzer display extend the power of the simulator to record and track program execution, actions on I/O, most peripherals and internal registers. The MPLAB X SIM Software Simulator fully supports symbolic debugging using the MPLAB XC Compilers, and the MPASM and MPLAB Assemblers. The software simulator offers the flexibility to develop and debug code outside of the hardware laboratory environment, making it an excellent, economical software development tool. 23.7 MPLAB REAL ICE In-Circuit Emulator System The MPLAB REAL ICE In-Circuit Emulator System is Microchip’s next generation high-speed emulator for Microchip Flash DSC and MCU devices. It debugs and programs all 8, 16 and 32-bit MCU, and DSC devices with the easy-to-use, powerful graphical user interface of the MPLAB X IDE. The emulator is connected to the design engineer’s PC using a high-speed USB 2.0 interface and is connected to the target with either a connector compatible with in-circuit debugger systems (RJ-11) or with the new high-speed, noise tolerant, LowVoltage Differential Signal (LVDS) interconnection (CAT5). The emulator is field upgradable through future firmware downloads in MPLAB X IDE. MPLAB REAL ICE offers significant advantages over competitive emulators including full-speed emulation, run-time variable watches, trace analysis, complex breakpoints, logic probes, a ruggedized probe interface and long (up to three meters) interconnection cables. DS40001455F-page 202 23.8 MPLAB ICD 3 In-Circuit Debugger System The MPLAB ICD 3 In-Circuit Debugger System is Microchip’s most cost-effective, high-speed hardware debugger/programmer for Microchip Flash DSC and MCU devices. It debugs and programs PIC Flash microcontrollers and dsPIC DSCs with the powerful, yet easy-to-use graphical user interface of the MPLAB IDE. The MPLAB ICD 3 In-Circuit Debugger probe is connected to the design engineer’s PC using a highspeed USB 2.0 interface and is connected to the target with a connector compatible with the MPLAB ICD 2 or MPLAB REAL ICE systems (RJ-11). MPLAB ICD 3 supports all MPLAB ICD 2 headers. 23.9 PICkit 3 In-Circuit Debugger/ Programmer The MPLAB PICkit 3 allows debugging and programming of PIC and dsPIC Flash microcontrollers at a most affordable price point using the powerful graphical user interface of the MPLAB IDE. The MPLAB PICkit 3 is connected to the design engineer’s PC using a fullspeed USB interface and can be connected to the target via a Microchip debug (RJ-11) connector (compatible with MPLAB ICD 3 and MPLAB REAL ICE). The connector uses two device I/O pins and the Reset line to implement in-circuit debugging and In-Circuit Serial Programming™ (ICSP™). 23.10 MPLAB PM3 Device Programmer The MPLAB PM3 Device Programmer is a universal, CE compliant device programmer with programmable voltage verification at VDDMIN and VDDMAX for maximum reliability. It features a large LCD display (128 x 64) for menus and error messages, and a modular, detachable socket assembly to support various package types. The ICSP cable assembly is included as a standard item. In Stand-Alone mode, the MPLAB PM3 Device Programmer can read, verify and program PIC devices without a PC connection. It can also set code protection in this mode. The MPLAB PM3 connects to the host PC via an RS-232 or USB cable. The MPLAB PM3 has high-speed communications and optimized algorithms for quick programming of large memory devices, and incorporates an MMC card for file storage and data applications.  2011-2016 Microchip Technology Inc. PIC16LF1902/3 23.11 Demonstration/Development Boards, Evaluation Kits, and Starter Kits A wide variety of demonstration, development and evaluation boards for various PIC MCUs and dsPIC DSCs allows quick application development on fully functional systems. Most boards include prototyping areas for adding custom circuitry and provide application firmware and source code for examination and modification. The boards support a variety of features, including LEDs, temperature sensors, switches, speakers, RS-232 interfaces, LCD displays, potentiometers and additional EEPROM memory. 23.12 Third-Party Development Tools Microchip also offers a great collection of tools from third-party vendors. These tools are carefully selected to offer good value and unique functionality. • Device Programmers and Gang Programmers from companies, such as SoftLog and CCS • Software Tools from companies, such as Gimpel and Trace Systems • Protocol Analyzers from companies, such as Saleae and Total Phase • Demonstration Boards from companies, such as MikroElektronika, Digilent® and Olimex • Embedded Ethernet Solutions from companies, such as EZ Web Lynx, WIZnet and IPLogika® The demonstration and development boards can be used in teaching environments, for prototyping custom circuits and for learning about various microcontroller applications. In addition to the PICDEM™ and dsPICDEM™ demonstration/development board series of circuits, Microchip has a line of evaluation kits and demonstration software for analog filter design, KEELOQ® security ICs, CAN, IrDA®, PowerSmart battery management, SEEVAL® evaluation system, Sigma-Delta ADC, flow rate sensing, plus many more. Also available are starter kits that contain everything needed to experience the specified device. This usually includes a single application and debug capability, all on one board. Check the Microchip web page (www.microchip.com) for the complete list of demonstration, development and evaluation kits.  2011-2016 Microchip Technology Inc. DS40001455F-page 203 PIC16LF1902/3 24.0 PACKAGING INFORMATION 24.1 Package Marking Information 28-Lead PDIP (600 mil) XXXXXXXXXXXXXXX XXXXXXXXXXXXXXX XXXXXXXXXXXXXXX YYWWNNN 28-Lead SOIC (7.50 mm) XXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXX YYWWNNN 28-Lead SSOP (5.30 mm) Example PIC16LF1902-I/P 1148017 Example PIC16LF1902 -E/SO e3 1148017 Example PIC16LF1902 -E/SS e3 1148017 Legend: XX...X Y YY WW NNN e3 * Note: DS40001455F-page 204 Customer-specific information Year code (last digit of calendar year) Year code (last 2 digits of calendar year) Week code (week of January 1 is week ‘01’) Alphanumeric traceability code Pb-free JEDEC® designator for Matte Tin (Sn) This package is Pb-free. The Pb-free JEDEC® designator e( 3 ) can be found on the outer packaging for this package. In the event the full Microchip part number cannot be marked on one line, it will be carried over to the next line, thus limiting the number of available characters for customer-specific information.  2011-2016 Microchip Technology Inc. PIC16LF1902/3 24.2 Package Marking Information 28-Lead UQFN (4x4x0.5 mm) PIN 1 Example PIN 1 Legend: XX...X Y YY WW NNN e3 * Note: PIC16 LF1903 E/MV e3 148017 Customer-specific information Year code (last digit of calendar year) Year code (last 2 digits of calendar year) Week code (week of January 1 is week ‘01’) Alphanumeric traceability code Pb-free JEDEC® designator for Matte Tin (Sn) This package is Pb-free. The Pb-free JEDEC® designator e( 3 ) can be found on the outer packaging for this package. In the event the full Microchip part number cannot be marked on one line, it will be carried over to the next line, thus limiting the number of available characters for customer-specific information.  2011-2016 Microchip Technology Inc. DS40001455F-page 205 PIC16LF1902/3 24.3 Package Details The following sections give the technical details of the packages. /HDG3ODVWLF'XDO,Q/LQH3±PLO%RG\>3',3@ 1RWH )RUWKHPRVWFXUUHQWSDFNDJHGUDZLQJVSOHDVHVHHWKH0LFURFKLS3DFNDJLQJ6SHFLILFDWLRQORFDWHGDW KWWSZZZPLFURFKLSFRPSDFNDJLQJ N E1 NOTE 1 1 2 3 D E A2 A L c b1 A1 b e eB 8QLWV 'LPHQVLRQ/LPLWV 1XPEHURI3LQV ,1&+(6 0,1 1 120 0$;  3LWFK H 7RSWR6HDWLQJ3ODQH $ ± ±  0ROGHG3DFNDJH7KLFNQHVV $  ±  %DVHWR6HDWLQJ3ODQH $  ± ± 6KRXOGHUWR6KRXOGHU:LGWK (  ±  0ROGHG3DFNDJH:LGWK (  ±  2YHUDOO/HQJWK '  ±  7LSWR6HDWLQJ3ODQH /  ±  /HDG7KLFNQHVV F  ±  E  ±  E  ±  H% ± ± 8SSHU/HDG:LGWK /RZHU/HDG:LGWK 2YHUDOO5RZ6SDFLQJ† %6&  1RWHV  3LQYLVXDOLQGH[IHDWXUHPD\YDU\EXWPXVWEHORFDWHGZLWKLQWKHKDWFKHGDUHD  †6LJQLILFDQW&KDUDFWHULVWLF  'LPHQVLRQV'DQG(GRQRWLQFOXGHPROGIODVKRUSURWUXVLRQV0ROGIODVKRUSURWUXVLRQVVKDOOQRWH[FHHGSHUVLGH  'LPHQVLRQLQJDQGWROHUDQFLQJSHU$60(6623@ 1RWH )RUWKHPRVWFXUUHQWSDFNDJHGUDZLQJVSOHDVHVHHWKH0LFURFKLS3DFNDJLQJ6SHFLILFDWLRQORFDWHGDW KWWSZZZPLFURFKLSFRPSDFNDJLQJ D N E E1 1 2 NOTE 1 b e c A2 A φ A1 L L1 8QLWV 'LPHQVLRQ/LPLWV 1XPEHURI3LQV 0,//,0(7(56 0,1 1 120 0$;  3LWFK H 2YHUDOO+HLJKW $ ± %6& ±  0ROGHG3DFNDJH7KLFNQHVV $    6WDQGRII $  ± ± 2YHUDOO:LGWK (    0ROGHG3DFNDJH:LGWK (    2YHUDOO/HQJWK '    )RRW/HQJWK /    )RRWSULQW / 5() /HDG7KLFNQHVV F  ± )RRW$QJOH  ƒ ƒ  ƒ /HDG:LGWK E  ±  1RWHV  3LQYLVXDOLQGH[IHDWXUHPD\YDU\EXWPXVWEHORFDWHGZLWKLQWKHKDWFKHGDUHD  'LPHQVLRQV'DQG(GRQRWLQFOXGHPROGIODVKRUSURWUXVLRQV0ROGIODVKRUSURWUXVLRQVVKDOOQRWH[FHHGPPSHUVLGH  'LPHQVLRQLQJDQGWROHUDQFLQJSHU$60(