ATMEGA8

Features • High-performance, Low-power AVR® 8-bit Microcontroller • Advanced RISC Architecture – 130 Powerful Instructions – Most Single-clock Cycle Execution – 32 x 8 General Purpose Working Registers – Fully Static Operation – Up to 16 MIPS Throughput at 16 MHz – On-chip 2-cycle Multiplier Nonvolatile Program and Data Memories – 8K Bytes of In-System Self-Programmable Flash Endurance: 10,000 Write/Erase Cycles – Optional Boot Code Section with Independent Lock Bits In-System Programming by On-chip Boot Program True Read-While-Write Operation – 512 Bytes EEPROM Endurance: 100,000 Write/Erase Cycles – 1K Byte Internal SRAM – Programming Lock for Software Security Peripheral Features – Two 8-bit Timer/Counters with Separate Prescaler, one Compare Mode – One 16-bit Timer/Counter with Separate Prescaler, Compare Mode, and Capture Mode – Real Time Counter with Separate Oscillator – Three PWM Channels – 8-channel ADC in TQFP and QFN/MLF package Eight Channels 10-bit Accuracy – 6-channel ADC in PDIP package Eight Channels 10-bit Accuracy – Byte-oriented Two-wire Serial Interface – Programmable Serial USART – Master/Slave SPI Serial Interface – Programmable Watchdog Timer with Separate On-chip Oscillator – On-chip Analog Comparator Special Microcontroller Features – Power-on Reset and Programmable Brown-out Detection – Internal Calibrated RC Oscillator – External and Internal Interrupt Sources – Five Sleep Modes: Idle, ADC Noise Reduction, Power-save, Power-down, and Standby I/O and Packages – 23 Programmable I/O Lines – 28-lead PDIP, 32-lead TQFP, and 32-pad QFN/MLF Operating Voltages – 2.7 - 5.5V (ATmega8L) – 4.5 - 5.5V (ATmega8) Speed Grades – 0 - 8 MHz (ATmega8L) – 0 - 16 MHz (ATmega8) Power Consumption at 4 Mhz, 3V, 25°C – Active: 3.6 mA – Idle Mode: 1.0 mA – Power-down Mode: 0.5 µA • • 8-bit with 8K Bytes In-System Programmable Flash ATmega8 ATmega8L • • • • • 2486QS–AVR–10/06 Pin Configurations PDIP (RESET) PC6 (RXD) PD0 (TXD) PD1 (INT0) PD2 (INT1) PD3 (XCK/T0) PD4 VCC GND (XTAL1/TOSC1) PB6 (XTAL2/TOSC2) PB7 (T1) PD5 (AIN0) PD6 (AIN1) PD7 (ICP1) PB0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 28 27 26 25 24 23 22 21 20 19 18 17 16 15 PC5 (ADC5/SCL) PC4 (ADC4/SDA) PC3 (ADC3) PC2 (ADC2) PC1 (ADC1) PC0 (ADC0) GND AREF AVCC PB5 (SCK) PB4 (MISO) PB3 (MOSI/OC2) PB2 (SS/OC1B) PB1 (OC1A) TQFP Top View PD2 (INT0) PD1 (TXD) PD0 (RXD) PC6 (RESET) PC5 (ADC5/SCL) PC4 (ADC4/SDA) PC3 (ADC3) PC2 (ADC2) 32 31 30 29 28 27 26 25 (INT1) PD3 (XCK/T0) PD4 GND VCC GND VCC (XTAL1/TOSC1) PB6 (XTAL2/TOSC2) PB7 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 24 23 22 21 20 19 18 17 PC1 (ADC1) PC0 (ADC0) ADC7 GND AREF ADC6 AVCC PB5 (SCK) 32 31 30 29 28 27 26 25 PD2 (INT0) PD1 (TXD) PD0 (RXD) PC6 (RESET) PC5 (ADC5/SCL) PC4 (ADC4/SDA) PC3 (ADC3) PC2 (ADC2) (T1) PD5 (AIN0) PD6 (AIN1) PD7 (ICP1) PB0 (OC1A) PB1 (SS/OC1B) PB2 (MOSI/OC2) PB3 (MISO) PB4 MLF Top View (INT1) PD3 (XCK/T0) PD4 GND VCC GND VCC (XTAL1/TOSC1) PB6 (XTAL2/TOSC2) PB7 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 24 23 22 21 20 19 18 17 PC1 (ADC1) PC0 (ADC0) ADC7 GND AREF ADC6 AVCC PB5 (SCK) 2 ATmega8(L) 2486QS–AVR–10/06 (T1) PD5 (AIN0) PD6 (AIN1) PD7 (ICP1) PB0 (OC1A) PB1 (SS/OC1B) PB2 (MOSI/OC2) PB3 (MISO) PB4 NOTE: The large center pad underneath the MLF packages is made of metal and internally connected to GND. It should be soldered or glued to the PCB to ensure good mechanical stability. If the center pad is left unconneted, the package might loosen from the PCB. ATmega8(L) Overview The ATmega8 is a low-power CMOS 8-bit microcontroller based on the AVR RISC architecture. By executing powerful instructions in a single clock cycle, the ATmega8 achieves throughputs approaching 1 MIPS per MHz, allowing the system designer to optimize power consumption versus processing speed. Figure 1. Block Diagram XTAL1 RESET PC0 - PC6 VCC XTAL2 PB0 - PB7 Block Diagram PORTC DRIVERS/BUFFERS PORTB DRIVERS/BUFFERS GND PORTC DIGITAL INTERFACE PORTB DIGITAL INTERFACE MUX & ADC AGND AREF PROGRAM COUNTER ADC INTERFACE TWI STACK POINTER TIMERS/ COUNTERS OSCILLATOR PROGRAM FLASH SRAM INTERNAL OSCILLATOR INSTRUCTION REGISTER GENERAL PURPOSE REGISTERS X WATCHDOG TIMER OSCILLATOR INSTRUCTION DECODER Y Z MCU CTRL. & TIMING CONTROL LINES ALU INTERRUPT UNIT AVR CPU STATUS REGISTER EEPROM PROGRAMMING LOGIC SPI USART + - COMP. INTERFACE PORTD DIGITAL INTERFACE PORTD DRIVERS/BUFFERS PD0 - PD7 3 2486QS–AVR–10/06 The AVR core combines a rich instruction set with 32 general purpose working registers. All the 32 registers are directly connected to the Arithmetic Logic Unit (ALU), allowing two independent registers to be accessed in one single instruction executed in one clock cycle. The resulting architecture is more code efficient while achieving throughputs up to ten times faster than conventional CISC microcontrollers. The ATmega8 provides the following features: 8K bytes of In-System Programmable Flash with Read-While-Write capabilities, 512 bytes of EEPROM, 1K byte of SRAM, 23 general purpose I/O lines, 32 general purpose working registers, three flexible Timer/Counters with compare modes, internal and external interrupts, a serial programmable USART, a byte oriented Two-wire Serial Interface, a 6-channel ADC (eight channels in TQFP and QFN/MLF packages) with 10-bit accuracy, a programmable Watchdog Timer with Internal Oscillator, an SPI serial port, and five software selectable power saving modes. The Idle mode stops the CPU while allowing the SRAM, Timer/Counters, SPI port, and interrupt system to continue functioning. The Powerdown mode saves the register contents but freezes the Oscillator, disabling all other chip functions until the next Interrupt or Hardware Reset. In Power-save mode, the asynchronous timer continues to run, allowing the user to maintain a timer base while the rest of the device is sleeping. The ADC Noise Reduction mode stops the CPU and all I/O modules except asynchronous timer and ADC, to minimize switching noise during ADC conversions. In Standby mode, the crystal/resonator Oscillator is running while the rest of the device is sleeping. This allows very fast start-up combined with low-power consumption. The device is manufactured using Atmel’s high density non-volatile memory technology. The Flash Program memory can be reprogrammed In-System through an SPI serial interface, by a conventional non-volatile memory programmer, or by an On-chip boot program running on the AVR core. The boot program can use any interface to download the application program in the Application Flash memory. Software in the Boot Flash Section will continue to run while the Application Flash Section is updated, providing true Read-While-Write operation. By combining an 8-bit RISC CPU with In-System SelfProgrammable Flash on a monolithic chip, the Atmel ATmega8 is a powerful microcontroller that provides a highly-flexible and cost-effective solution to many embedded control applications. The ATmega8 AVR is supported with a full suite of program and system development tools, including C compilers, macro assemblers, program debugger/simulators, In-Circuit Emulators, and evaluation kits. Disclaimer Typical values contained in this datasheet are based on simulations and characterization of other AVR microcontrollers manufactured on the same process technology. Min and Max values will be available after the device is characterized. 4 ATmega8(L) 2486QS–AVR–10/06 ATmega8(L) Pin Descriptions VCC GND Port B (PB7..PB0) XTAL1/XTAL2/TOSC1/TOSC2 Digital supply voltage. Ground. Port B is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port B output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port B pins that are externally pulled low will source current if the pull-up resistors are activated. The Port B pins are tri-stated when a reset condition becomes active, even if the clock is not running. Depending on the clock selection fuse settings, PB6 can be used as input to the inverting Oscillator amplifier and input to the internal clock operating circuit. Depending on the clock selection fuse settings, PB7 can be used as output from the inverting Oscillator amplifier. If the Internal Calibrated RC Oscillator is used as chip clock source, PB7..6 is used as TOSC2..1 input for the Asynchronous Timer/Counter2 if the AS2 bit in ASSR is set. The various special features of Port B are elaborated in “Alternate Functions of Port B” on page 58 and “System Clock and Clock Options” on page 25. Port C (PC5..PC0) Port C is an 7-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port C output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port C pins that are externally pulled low will source current if the pull-up resistors are activated. The Port C pins are tri-stated when a reset condition becomes active, even if the clock is not running. If the RSTDISBL Fuse is programmed, PC6 is used as an I/O pin. Note that the electrical characteristics of PC6 differ from those of the other pins of Port C. If the RSTDISBL Fuse is unprogrammed, PC6 is used as a Reset input. A low level on this pin for longer than the minimum pulse length will generate a Reset, even if the clock is not running. The minimum pulse length is given in Table 15 on page 38. Shorter pulses are not guaranteed to generate a Reset. The various special features of Port C are elaborated on page 61. Port D (PD7..PD0) Port D is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port D output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port D pins that are externally pulled low will source current if the pull-up resistors are activated. The Port D pins are tri-stated when a reset condition becomes active, even if the clock is not running. Port D also serves the functions of various special features of the ATmega8 as listed on page 63. RESET Reset input. A low level on this pin for longer than the minimum pulse length will generate a reset, even if the clock is not running. The minimum pulse length is given in Table 15 on page 38. Shorter pulses are not guaranteed to generate a reset. PC6/RESET 5 2486QS–AVR–10/06 AVCC AVCC is the supply voltage pin for the A/D Converter, Port C (3..0), and ADC (7..6). It should be externally connected to VCC, even if the ADC is not used. If the ADC is used, it should be connected to VCC through a low-pass filter. Note that Port C (5..4) use digital supply voltage, VCC. AREF is the analog reference pin for the A/D Converter. In the TQFP and QFN/MLF package, ADC7..6 serve as analog inputs to the A/D converter. These pins are powered from the analog supply and serve as 10-bit ADC channels. AREF ADC7..6 (TQFP and QFN/MLF Package Only) 6 ATmega8(L) 2486QS–AVR–10/06 ATmega8(L) Resources A comprehensive set of development tools, application notes and datasheets are available for download on http://www.atmel.com/avr. 7 2486QS–AVR–10/06 Register Summary Address 0x3F (0x5F) 0x3E (0x5E) 0x3D (0x5D) 0x3C (0x5C) 0x3B (0x5B) 0x3A (0x5A) 0x39 (0x59) 0x38 (0x58) 0x37 (0x57) 0x36 (0x56) 0x35 (0x55) 0x34 (0x54) 0x33 (0x53) 0x32 (0x52) 0x31 (0x51) 0x30 (0x50) 0x2F (0x4F) 0x2E (0x4E) 0x2D (0x4D) 0x2C (0x4C) 0x2B (0x4B) 0x2A (0x4A) 0x29 (0x49) 0x28 (0x48) 0x27 (0x47) 0x26 (0x46) 0x25 (0x45) 0x24 (0x44) 0x23 (0x43) 0x22 (0x42) 0x21 (0x41) 0x20(1) (0x40)(1) 0x1F (0x3F) 0x1E (0x3E) 0x1D (0x3D) 0x1C (0x3C) 0x1B (0x3B) 0x1A (0x3A) 0x19 (0x39) 0x18 (0x38) 0x17 (0x37) 0x16 (0x36) 0x15 (0x35) 0x14 (0x34) 0x13 (0x33) 0x12 (0x32) 0x11 (0x31) 0x10 (0x30) 0x0F (0x2F) 0x0E (0x2E) 0x0D (0x2D) 0x0C (0x2C) 0x0B (0x2B) 0x0A (0x2A) 0x09 (0x29) 0x08 (0x28) 0x07 (0x27) 0x06 (0x26) 0x05 (0x25) 0x04 (0x24) 0x03 (0x23) 0x02 (0x22) Name SREG SPH SPL Reserved GICR GIFR TIMSK TIFR SPMCR TWCR MCUCR MCUCSR TCCR0 TCNT0 OSCCAL SFIOR TCCR1A TCCR1B TCNT1H TCNT1L OCR1AH OCR1AL OCR1BH OCR1BL ICR1H ICR1L TCCR2 TCNT2 OCR2 ASSR WDTCR UBRRH UCSRC EEARH EEARL EEDR EECR Reserved Reserved Reserved PORTB DDRB PINB PORTC DDRC PINC PORTD DDRD PIND SPDR SPSR SPCR UDR UCSRA UCSRB UBRRL ACSR ADMUX ADCSRA ADCH ADCL TWDR TWAR Bit 7 I – SP7 INT1 INTF1 OCIE2 OCF2 SPMIE TWINT SE – – Bit 6 T – SP6 INT0 INTF0 TOIE2 TOV2 RWWSB TWEA SM2 – – Bit 5 H – SP5 – – TICIE1 ICF1 – TWSTA SM1 – – Bit 4 S – SP4 – – OCIE1A OCF1A RWWSRE TWSTO SM0 – – Bit 3 V – SP3 – – OCIE1B OCF1B BLBSET TWWC ISC11 WDRF – Bit 2 N SP10 SP2 – – TOIE1 TOV1 PGWRT TWEN ISC10 BORF CS02 Bit 1 Z SP9 SP1 IVSEL – – – PGERS – ISC01 EXTRF CS01 Bit 0 C SP8 SP0 IVCE – TOIE0 TOV0 SPMEN TWIE ISC00 PORF CS00 Page 11 13 13 49, 67 68 72, 102, 122 73, 103, 122 213 171 33, 66 41 72 72 31 Timer/Counter0 (8 Bits) Oscillator Calibration Register – COM1A1 ICNC1 – COM1A0 ICES1 – COM1B1 – – COM1B0 WGM13 ACME FOC1A WGM12 PUD FOC1B CS12 PSR2 WGM11 CS11 PSR10 WGM10 CS10 58, 75, 123, 193 97 100 101 101 101 101 101 101 102 102 Timer/Counter1 – Counter Register High byte Timer/Counter1 – Counter Register Low byte Timer/Counter1 – Output Compare Register A High byte Timer/Counter1 – Output Compare Register A Low byte Timer/Counter1 – Output Compare Register B High byte Timer/Counter1 – Output Compare Register B Low byte Timer/Counter1 – Input Capture Register High byte Timer/Counter1 – Input Capture Register Low byte FOC2 WGM20 COM21 COM20 WGM21 CS22 CS21 CS20 Timer/Counter2 (8 Bits) Timer/Counter2 Output Compare Register – – URSEL URSEL – EEAR7 – – – – UMSEL – EEAR6 – – – – UPM1 – EEAR5 – – WDCE – UPM0 – EEAR4 – USBS – EEAR3 EERIE – EEAR2 EEMWE AS2 WDE TCN2UB WDP2 UCSZ1 OCR2UB WDP1 UBRR[11:8] UCSZ0 – EEAR1 EEWE UCPOL EEAR8 EEAR0 EERE TCR2UB WDP0 117 119 119 119 43 158 156 20 20 20 20 EEPROM Data Register PORTB7 DDB7 PINB7 – – – PORTD7 DDD7 PIND7 SPIF SPIE RXC RXCIE ACD REFS1 ADEN PORTB6 DDB6 PINB6 PORTC6 DDC6 PINC6 PORTD6 DDD6 PIND6 WCOL SPE TXC TXCIE ACBG REFS0 ADSC PORTB5 DDB5 PINB5 PORTC5 DDC5 PINC5 PORTD5 DDD5 PIND5 – DORD UDRE UDRIE ACO ADLAR ADFR PORTB4 DDB4 PINB4 PORTC4 DDC4 PINC4 PORTD4 DDD4 PIND4 – MSTR FE RXEN ACI – ADIF PORTB3 DDB3 PINB3 PORTC3 DDC3 PINC3 PORTD3 DDD3 PIND3 – CPOL DOR TXEN ACIE MUX3 ADIE PORTB2 DDB2 PINB2 PORTC2 DDC2 PINC2 PORTD2 DDD2 PIND2 – CPHA PE UCSZ2 ACIC MUX2 ADPS2 PORTB1 DDB1 PINB1 PORTC1 DDC1 PINC1 PORTD1 DDD1 PIND1 – SPR1 U2X RXB8 ACIS1 MUX1 ADPS1 PORTB0 DDB0 PINB0 PORTC0 DDC0 PINC0 PORTD0 DDD0 PIND0 SPI2X SPR0 MPCM TXB8 ACIS0 MUX0 ADPS0 65 65 65 65 65 65 65 65 65 131 131 129 153 154 155 158 194 205 207 208 208 173 SPI Data Register USART I/O Data Register USART Baud Rate Register Low byte ADC Data Register High byte ADC Data Register Low byte Two-wire Serial Interface Data Register TWA6 TWA5 TWA4 TWA3 TWA2 TWA1 TWA0 TWGCE 174 8 ATmega8(L) 2486QS–AVR–10/06 ATmega8(L) Register Summary (Continued) Address 0x01 (0x21) 0x00 (0x20) Name TWSR TWBR Bit 7 TWS7 Bit 6 TWS6 Bit 5 TWS5 Bit 4 TWS4 Bit 3 TWS3 Bit 2 – Bit 1 TWPS1 Bit 0 TWPS0 Page 173 171 Two-wire Serial Interface Bit Rate Register Notes: 1. Refer to the USART description for details on how to access UBRRH and UCSRC. 2. For compatibility with future devices, reserved bits should be written to zero if accessed. Reserved I/O memory addresses should never be written. 3. Some of the Status Flags are cleared by writing a logical one to them. Note that the CBI and SBI instructions will operate on all bits in the I/O Register, writing a one back into any flag read as set, thus clearing the flag. The CBI and SBI instructions work with registers 0x00 to 0x1F only. 9 2486QS–AVR–10/06 Instruction Set Summary Mnemonics ADD ADC ADIW SUB SUBI SBC SBCI SBIW AND ANDI OR ORI EOR COM NEG SBR CBR INC DEC TST CLR SER MUL MULS MULSU FMUL FMULS FMULSU RJMP IJMP RCALL ICALL RET RETI CPSE CP CPC CPI SBRC SBRS SBIC SBIS BRBS BRBC BREQ BRNE BRCS BRCC BRSH BRLO BRMI BRPL BRGE BRLT BRHS BRHC BRTS BRTC BRVS BRVC Rd,Rr Rd,Rr Rd,Rr Rd,K Rr, b Rr, b P, b P, b s, k s, k k k k k k k k k k k k k k k k k k Operands Rd, Rr Rd, Rr Rdl,K Rd, Rr Rd, K Rd, Rr Rd, K Rdl,K Rd, Rr Rd, K Rd, Rr Rd, K Rd, Rr Rd Rd Rd,K Rd,K Rd Rd Rd Rd Rd Rd, Rr Rd, Rr Rd, Rr Rd, Rr Rd, Rr Rd, Rr k Add two Registers Description Rd ← Rd + Rr Operation Flags Z,C,N,V,H Z,C,N,V,H Z,C,N,V,S Z,C,N,V,H Z,C,N,V,H Z,C,N,V,H Z,C,N,V,H Z,C,N,V,S Z,N,V Z,N,V Z,N,V Z,N,V Z,N,V Z,C,N,V Z,C,N,V,H Z,N,V Z,N,V Z,N,V Z,N,V Z,N,V Z,N,V None Z,C Z,C Z,C Z,C Z,C Z,C None None None None None I None Z, N,V,C,H Z, N,V,C,H Z, N,V,C,H None None None None None None None None None None None None None None None None None None None None None None #Clocks 1 1 2 1 1 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 3 3 4 4 1/2/3 1 1 1 1/2/3 1/2/3 1/2/3 1/2/3 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 ARITHMETIC AND LOGIC INSTRUCTIONS Add with Carry two Registers Add Immediate to Word Subtract two Registers Subtract Constant from Register Subtract with Carry two Registers Subtract with Carry Constant from Reg. Subtract Immediate from Word Logical AND Registers Logical AND Register and Constant Logical OR Registers Logical OR Register and Constant Exclusive OR Registers One’s Complement Two’s Complement Set Bit(s) in Register Clear Bit(s) in Register Increment Decrement Test for Zero or Minus Clear Register Set Register Multiply Unsigned Multiply Signed Multiply Signed with Unsigned Fractional Multiply Unsigned Fractional Multiply Signed Fractional Multiply Signed with Unsigned Relative Jump Indirect Jump to (Z) Relative Subroutine Call Indirect Call to (Z) Subroutine Return Interrupt Return Compare, Skip if Equal Compare Compare with Carry Compare Register with Immediate Skip if Bit in Register Cleared Skip if Bit in Register is Set Skip if Bit in I/O Register Cleared Skip if Bit in I/O Register is Set Branch if Status Flag Set Branch if Status Flag Cleared Branch if Equal Branch if Not Equal Branch if Carry Set Branch if Carry Cleared Branch if Same or Higher Branch if Lower Branch if Minus Branch if Plus Branch if Greater or Equal, Signed Branch if Less Than Zero, Signed Branch if Half Carry Flag Set Branch if Half Carry Flag Cleared Branch if T Flag Set Branch if T Flag Cleared Branch if Overflow Flag is Set Branch if Overflow Flag is Cleared Rd ← Rd + Rr + C Rdh:Rdl ← Rdh:Rdl + K Rd ← Rd - Rr Rd ← Rd - K Rd ← Rd - Rr - C Rd ← Rd - K - C Rdh:Rdl ← Rdh:Rdl - K Rd ← Rd • Rr Rd ← Rd • K Rd ← Rd v Rr Rd ← Rd v K Rd ← Rd ⊕ Rr Rd ← 0xFF − Rd Rd ← 0x00 − Rd Rd ← Rd v K Rd ← Rd • (0xFF - K) Rd ← Rd + 1 Rd ← Rd − 1 Rd ← Rd • Rd Rd ← Rd ⊕ Rd Rd ← 0xFF R1:R0 ← Rd x Rr R1:R0 ← Rd x Rr R1:R0 ← Rd x Rr 1 R1:R0 ← (Rd x Rr)