PRODUCT SPECIFICATION
2.4GHz RF transceiver with
nRF24E1
embedded
8051 compatible micro-controller and
9 input, 10 bit ADC
FEATURES
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nRF2401 2.4GHz RF transceiver
8051 compatible micro-controller
compatible with nRF24E2
9 input 10 bit ADC 100kSPS
Single 1.9V to 3.6V supply
Internal voltage regulators
2 µA standby with wakeup on timer
or external pin
Internal VDD monitoring
Supplied in 36 pin QFN (6x6mm)
package
0.18µm CMOS technology
Mask programmable version available
Low Bill- of Material
Ease of design
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Wireless gamepads
Wireless headsets
Wireless keyboards
Wireless mouse
Wireless toys
Intelligent sports equipment
Industrial sensors
PC peripherals
Phone peripherals
Tags
Alarms
Remote control
APPLICATIONS
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PRODUCT SPECIFICATION
nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
TABLE OF CONTENT
1 GENERAL DESCRIPTION.....................................................................................4
1.1 Quick Reference Data.........................................................................................4
1.2 Block Diagram....................................................................................................5
1.3 Pin Diagram........................................................................................................6
1.4 Glossary of Terms...............................................................................................8
2 ARCHITECTURAL OVERVIEW............................................................................9
2.1 Microcontroller...................................................................................................9
2.2 PWM...............................................................................................................11
2.3 SPI...................................................................................................................11
2.4 Port Logic ........................................................................................................12
2.5 Power Management..........................................................................................12
2.6 RTC Wakeup Timer, Watchdog and RC Oscillator...........................................12
2.7 XTAL Oscillator...............................................................................................12
2.8 AD Converter...................................................................................................12
2.9 Radio Transceiver.............................................................................................13
3 I/O PORTS ............................................................................................................14
3.1 I/O port behavior during RESET.......................................................................14
3.2 Port 0 (P0) .......................................................................................................14
3.3 Port 1 (P1 or SPI port).....................................................................................16
4 nRF2401 2.4GHz TRANSCEIVER SUBSYSTEM ................................................20
4.1 RADIO port (Port 2)........................................................................................20
4.2 Modes of operation ..........................................................................................22
4.3 Device configuration..........................................................................................28
4.4 Data package Description.................................................................................41
4.5 Important RF Timing Data.................................................................................42
5 A/D CONVERTER ................................................................................................47
5.1 A/D converter subsystem block diagram............................................................48
5.2 A/D converter registers.....................................................................................48
5.3 A/D converter usage .........................................................................................50
5.4 A/D Converter timing........................................................................................52
5.5 Analog interface guidelines ................................................................................53
6 PWM .....................................................................................................................54
7 INTERRUPTS........................................................................................................55
7.1 Interrupt SFRs..................................................................................................55
7.2 Interrupt Processing..........................................................................................58
7.3 Interrupt Masking .............................................................................................59
7.4 Interrupt Priorities.............................................................................................59
7.5 Interrupt Sampling.............................................................................................60
7.6 Interrupt Latency..............................................................................................60
7.7 Interrupt Latency from Power Down Mode.......................................................60
7.8 Single-Step Operation.......................................................................................60
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PRODUCT SPECIFICATION
nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
8
WAKEUP TIMER AND WATCHDOG................................................................61
8.1 Tick calibration.................................................................................................61
8.2 RTC Wakeup timer ..........................................................................................62
8.3 Watchdog.........................................................................................................62
8.4 Reset................................................................................................................64
9 POWER SAVING MODES...................................................................................65
9.1 Idle Mode ........................................................................................................65
9.2 Stop Mode.......................................................................................................66
9.3 Power down mode ...........................................................................................66
10
MICROCONTROLLER.....................................................................................68
10.1 Memory Organization.......................................................................................68
10.2 Program format in external EEPROM................................................................69
10.3 Instruction Set...................................................................................................70
10.4 Instruction Timing..............................................................................................77
10.5 Dual Data Pointers............................................................................................77
10.6 Special Function Registers.................................................................................78
10.7 SFR registers unique to nRF24E1 .....................................................................82
10.8 Timers/Counters ...............................................................................................84
10.9 Serial Interface..................................................................................................92
11
ELECTRICAL SPECIFICATIONS..................................................................102
12
PACKAGE OUTLINE .....................................................................................104
12.1 GREEN PACKAGE OUTLINE ....................................................................104
12.2 PACKAGE OUTLINE, saw type...................................................................105
13
ABSOLUTE MAXIMUM RATINGS...............................................................106
14
Peripheral RF Information..................................................................................108
14.2 PCB layout and de-coupling guidelines............................................................109
15
Application example...........................................................................................110
15.1 nRF24E1 with single ended matching network.................................................110
15.2 PCB layout example .......................................................................................112
16
Table of Figures.................................................................................................113
17
Table of Tables..................................................................................................114
18
DEFINITIONS .................................................................................................116
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PRODUCT SPECIFICATION
nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
1
GENERAL DESCRIPTION
The nRF24E1 is a nRF2401 2.4GHz radio transceiver with an embedded 8051 compatible
microcontroller and a 10-bit 9 input 100 kSPS AD converter. The circuit is supplied by
only one voltage in range 1.9V to 3.6V. The nRF24E1 supports the proprietary and
innovative modes of the nRF2401 such as ShockBurst™ and DuoCeiver™.
nRF24E1 is a superset of the nRF24E2 chip, which means that it contains all functions of
nRF24E2, and that it is fully program compatible with nRF24E2.
1.1 Quick Reference Data
Parameter
Minimum supply voltage
Temperature range
Maximum RF output power
RF receiver sensitivity
Maximum RF burst data rate
Supply current for microcontroller @ 16MHz @3V
Supply current for ADC @100 kSPS
Supply current for RF transmit @ -5dBm output power
Supply current for RF receive @1000 kbps
Supply current in Power Down mode
max CPU clock frequency
max AD conversion rate
ADC Differential nonlinearity (DNL)
ADC Integral nonlinearity (INL)
ADC Spurious free dynamic range (SFDR)
Package
Value
Unit
1.9
-40 to +85
0
-90
1000
3
0.9
10.5
19
2
20
100
±0.5
±0.75
65
36 pin QFN 6x6
V
°C
dBm
dBm
kbps
mA
mA
mA
mA
µΑ
MHz
kSPS
LSB
LSB
dB
Table 1-1 : nRF24E1 quick reference data
Type Number
Description
Version
NRF24E1 IC
NRF24E1G IC
NRF24E1-EVKIT
36 pin QFN 6x6, saw
36 pin QFN 6x6, green package
Evaluation kit
A
A
1.0
Table 1-2 : nRF24E1 ordering information
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PRODUCT SPECIFICATION
nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
1.2 Block Diagram
4k byte
RAM 1
AREF
AIN0
512 byte 256 byte
ROM
RAM
VDD_PA = 1.8V
ANT1
7-channel interrupt
AIN1
UART0
AIN2
AIN3
AIN4
ANT2
Timer 0
nAD10100K
10-Bit
100kSPS
A/D converter
nRF2401
2.4GHz
Radio
Tranceiver
Timer 1
Timer 2
VSS_PA = 0V
BIAS
AIN5
CPU
AIN6
8051
compatible
Microcontroller
AIN7
IREF
22kΩ
XC1
XTAL
oscillator
XC2
DVDD
PWM
WAKEUP
timer
Power mgmt
Regulators
Reset
Low power
RC
oscillator
P0.7 (DIO9)
P0.6 (DIO8)
P0.5 (DIO7)
P0.4 (DIO6)
P0.3 (DIO5)
P0.2 (DIO4)
P0.1 (DIO3)
P0.0 (DIO2)
P1.1 (DIO1)
P1.0 (DIO0)
Port logic
P1.2 (DIN0)
3
VSS
4
DVDD2
VDD
WATCHDOG
SPI
SDO SCK SDI CSN
25320
EEPROM
Figure 1-1 nRF24E1 block diagram plus external components
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PRODUCT SPECIFICATION
nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
1.3 Pin Diagram
P1.2 (DIN0 )
AIN1
AIN2
VSS
VDD
VSS
AIN3
AIN4
AREF
36
35
34
33
32
31
30
29
28
VDD
1
27
IREF
AIN0
2
26
AIN5
DVDD2
3
25
AIN6
nRF24E1
QFN36 6x6
P1.0/T2 (DIO0)
4
24
AIN7
P1.1 (DIO1)
5
23
VSS
P0.0 (DIO2)
6
22
VDD
P0.1/RXD (DIO3)
7
21
VSS_PA
P0.2/TXD (DIO4)
8
20
ANT2
P0.3/INT0_N (DIO5)
9
19
ANT1
10
11
12
13
14
15
16
17
18
P0.4/INT1_N (DIO6)
P0.5/T0 (DIO7)
P0.6/T1 (DIO8)
P0.7/PWM (DIO9)
DVDD
VSS
XC2
XC1
VDD_PA
Pin
1
2
3
Name
VDD
AIN0
DVDD2
4
P1.0/T2
Pin function
Power
Analog input
Regulated
power
Digital I/O
5
6
7
8
P1.1
P0.0
P0.1/RXD
P0.2/TXD
Digital I/O
Digital I/O
Digital I/O
Digital I/O
Description
Power Supply (1.9-3.6 V DC)
ADC input 0
Digital Power Supply , must be connected to
regulator output DVDD
Port 1, bit 0 or T2 timer input or SPI clock or
DIO0
Port 1, bit 1 or SPI dataout or DIO1
Port 0, bit 0 or EEPROM.CSN or DIO2
Port 0, bit 1 or UART.RXD or DIO3
Port 0, bit 2 or UART.TXD or DIO4
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PRODUCT SPECIFICATION
nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
9
10
11
12
13
14
P0.3/INT0_N
P0.4/INT1_N
P0.5/T0
P0.6/T1
P0.7/PWM
DVDD
15
16
17
18
VSS
XC2
XC1
VDD_PA
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
ANT1
ANT2
VSS_PA
VDD
VSS
AIN7
AIN6
AIN5
IREF
AREF
AIN4
AIN3
VSS
VDD
VSS
AIN2
AIN1
P1.2
Digital I/O
Digital I/O
Digital I/O
Digital I/O
Digital I/O
Regulator
output
Power
Analog output
Analog input
Regulator
output
RF
RF
Power
Power
Power
Analog input
Analog input
Analog input
Analog input
Analog input
Analog input
Analog input
Power
Power
Power
Analog input
Analog input
Digital input
Port 0, bit 3 or INT0_N interrupt or DIO5
Port 0, bit 4 or INT1_N interrupt or DIO6
Port 0, bit 5 or T0 timer input or DIO7
Port 0, bit 6 or T1 timer input or DIO8
Port 0, bit 7 or PWM output or DIO9
Digital voltage regulator output for de-coupling
and feed to DVVD2
Ground (0V)
Crystal Pin 2
Crystal Pin 1
DC supply (+1.8V) to RF Power Amplifier
(ANT1,ANT2) only
Antenna interface 1
Antenna interface 2
Ground (0V)
Power Supply (1.9-3.6 V DC)
Ground (0V)
ADC input 7
ADC input 6
ADC input 5
Connection to external Bias reference resistor
ADC reference voltage
ADC input 4
ADC input 3
Ground (0V)
Power Supply (1.9-3.6 V DC)
Ground (0V)
ADC input 2
ADC input 1
Port 1, bit 2 or SPI datain or DIN0
Table 1-3 : nRF24E1 pin function
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PRODUCT SPECIFICATION
nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
1.4 Glossary of Terms
Term
Description
ADC
CLK
CRC
CS
CE
DR
FS
GFSK
GPIO
ISM
kSPS
MCU
OD
P0 (or P1)
PWM
PWR_DWN
PWR_UP
RTC
RX
SFR
SPI
SPS
ST_BY
TX
XTAL
Analog to Digital Converter
Clock
Cyclic Redundancy Check
Chip Select
Chip Enable
Data Ready
Full Scale
Gaussian Frequency Shift Keying
General Purpose In Out
Industrial-Scientific-Medical
kilo Samples per Second
Microcontroller Unit
Overdrive
(8051) In / Out Port 0 (or Port 1)
Pulse Width Modulation
Power Down
Power Up
Real Time Clock
Receive
(8051) Special Function Register
Serial Peripheral Interface
Samples per Second
Standby
Transmit
Crystal (oscillator)
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nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
2
ARCHITECTURAL OVERVIEW
This section will give a brief overview of each of the blocks in the block diagram in Figure
1-1.
2.1 Microcontroller
The nRF24E1 microcontroller is instruction set compatible with the industry standard 8051.
Instruction timing is slightly different from the industry standard, typically each instruction will
use from 4 to 20 clock cycles, compared with 12 to 48 for the “standard”. The interrupt
controller is extended to support 5 additional interrupt sources; ADC, SPI, RF receiver 1,
RF receiver 2 and wakeup timer. There are also 3 timers which are 8052 compatible, plus
some extensions, in the microcontroller core. An 8051 compatible UART that can use
timer1 or timer2 for baud rate generation in the traditional asynchronous modes is included.
The CPU is equipped with 2 data pointers to facilitate easier moving of data in the XRAM
area, which is a common 8051 extension. The microcontroller clock is derived directly from
the crystal oscillator.
2.1.1 Memory configuration
The microcontroller has a 256 byte data ram (8052 compatible, with the upper half only
addressable by register indirect addressing). A small ROM of 512 bytes, contains a
bootstrap loader that is executed automatically after power on reset or if initiated by
software later. The user program is normally loaded into a 4k byte RAM1 from an external
serial EEPROM by the bootstrap loader. The 4k byte RAM may also (partially) be used for
data storage in some applications.
2.1.2 Boot EEPROM/FLASH
If the mask ROM option is not used, the program code for the device must be loaded from
an external non-volatile memory. The default boot loader expects this to be a “generic
25320” EEPROM with SPI interface. These memories are available from several vendors
with supply ranges down to 1.8V. The SPI interface uses the pins P1.2/DIN0 (EEPROM
SDO), P1.0/DIO0 (EEPROM SCK), P1.1/DIO1 (EEPROM SDI) and P0.0/DIO2
(EEPROM CSN). When the boot is completed, the P1.2/DIN0, P1.0/DIO0 and
P1.1/DIO1 pins may be used for other purposes such as other SPI devices or GPIO.
2.1.3 Register map
The SFR (Special Function Registers) control several of the features of the nRF24E1. Most
of the nRF24E1 SFRs are identical to the standard 8051 SFRs. However, there are
additional SFRs that control features that are not available in the standard 8051.
1
Optionally this 4k block of memory can be configured as 2k mask ROM and 2k RAM or 4 k mask ROM
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nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
The SFR map is shown in the table below. The registers with grey background are registers
with industry standard 8051 behavior. Note that the function of P0 and P1 are somewhat
different from the “standard” even if the conventional addresses (0x80 and 0x90) are used
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nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
X000
F8
F0
E8
E0
D8
D0
C8
C0
B8
X010
X011
X100
X101
X110
X111
RCAP2L
RCAP2H
TL2
TH2
T1_1V2
T2_1V2
DEV_
OFFSET
CK_
CTRL
SPI
CLK
REGX
_LSB
ADC
STATIC
TICK_
DV
REGX
_CTRL
TEST_
MODE
P0_DIR
P0_ALT
P1_DIR
P1_ALT
B
EIE
ACC
EICON
PSW
T2CON
IP
RSTREAS
B0
A8
IE
A0
RADIO
(P2)
SCON
98
90
88
80
X001
EIP
PWM
CON
ADCCON
SPI
_DATA
PWM
DUTY
ADC
DATAH
SPI
_CTRL
REGX
_MSB
ADC
DATAL
SBUF
P1
EXIF
MPAGE
TCON
TMOD
TL0
TL1
TH0
TH1
CKCON
SPC_FNC
P0
SP
DPL
DPH
DPL1
DPH1
DPS
PCON
Table 2-1 : SFR Register map
2.2 PWM
The nRF24E1 has one programmable PWM output, which is the alternate function
of PO.7 at pin DIO9.
The resolution of the PWM is software programmable to 6, 7 or 8 bits.
The frequency of the PWM signal is programmable via a 6 bit prescaler from the XTAL
oscillator.
The duty cycle is programmable between 0% and 100% via one 8-bit register.
2.3 SPI
nRF24E1 features a simple single buffered SPI master. The 3 lines of the SPI bus (SDI,
SCK and SDO) are multiplexed (by writing to register SPI_CTRL) between the GPIO pins
(P1.2/DIN0, P1.0/DIO0 and P1.1/DIO1) and the RF transceiver. The SPI hardware does
not generate any chip select signal. The programmer will typically use GPIO bits (from port
P0) to act as chip selects for one or more external SPI devices. When the SPI interfaces the
RF transceiver, the chip selects are available in an internal GPIO port, P2.
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2.4 Port Logic
The device has 1 general purpose input and 10 general purpose bi-directional pins. These
are by default configured as GPIO pins controlled by the ports P0 (DIO2 to DIO9) and P1
(DIO0, DIO1, DIN0) of the microcontroller.
Most of the GPIO pins can be used for multiple purposes under program control. The
alternate functions include two external interrupts, UART RXD and TXD, a SPI master
port, three enable/count signals for the timers and the PWM output.
2.5 Power Management
The nRF24E1 can be set into a low power down mode under program control, and also the
ADC and RF subsystems can be turned on or off under program control. The CPU will
stop, but all RAM’s and registers maintain their values. The low power RC oscillator is
running, and so are the watchdog and the RTC wakeup timer (if enabled by software). The
current consumption in this mode is typically 2µA.
The device can exit the power down mode by an external pin (INT0_N or INT1_N) if
enabled, by the wakeup timer if enabled or by a watchdog reset.
2.6 RTC Wakeup Timer, Watchdog and RC Oscillator
The nRF24E1 contains a low power RC oscillator which can not be disabled, so it will run
continuously as long as VDD = 1.8V.
RTC Wakeup Timer and Watchdog are two 16 bit programmable timers that run on the RC
oscillator LP_OSC clock. The resolution of the watchdog and wakeup timer is
programmable from approximately 300µs to approximately 80ms. By default the resolution
is 10ms. The wakeup timer can be started and stopped by user software. The watchdog is
disabled after a reset, but if activated it can not be disabled again, except by another reset
2.7 XTAL Oscillator
Both the microcontroller, ADC and RF front end run on a crystal oscillator generated clock.
A range of crystals frequencies from 4 to 20 MHz may be utilised, but 16 MHz is
recommended since it gives best over all performance. For details, please see Crystal
Specification on page 108. The oscillator may be started and stopped as requested by
software.
2.8 AD Converter
The nRF24E1 AD converter has 10 bit dynamic range and linearity with a conversion time
of 48 CPU instruction cycles per 10-bit result.
The reference for the AD converter is software selectable between the AREF input and an
internal 1.22V bandgap reference.
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PRODUCT SPECIFICATION
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The converter has 9 inputs selectable by software. Selecting one of the inputs 0 to 7 will
convert the voltage on the respective AIN0 to AIN7 pin.
Input 8 enables software to monitor the nRF24E1 supply voltage by converting an internal
input that is VDD/3 with the 1.22V internal reference selected.
The AD converter is typically used in a start/stop mode. The sampling time is then under
software control.
The converter is by default configured as 10 bits. For special requirements, the AD
converter can be configured by software to perform 6, 8 or 12 bit conversions. The
converter may also be used in differential mode with AIN0 used as inverting input and one
of the other 7 external inputs used as noninverting input. In that case the conversion time can
be reduced to approximately 2 µs.
2.9 Radio Transceiver
The transceiver part of the circuit has identical functionality to the nRF2401 single chip RF
transceiver. It is accessed through an internal parallel port and / or an internal SPI. The data
ready signals for each DuoCeiver™ receiver output can be programmed as interrupts to the
microcontroller or polled via a GPIO port.
nRF2401 is a radio transceiver for the world wide 2.4 - 2.5 GHz ISM band. The
transceiver consists of a fully integrated frequency synthesizer, a power amplifier, a
modulator and two receiver units. Output power and frequency channels and other RF
parameters are easily programmable by use of the RADIO register, SFR 0xA0. RF current
consumption is only 10.5 mA in TX mode (output power -5dBm) and 18 mA in RX mode.
For power saving the transceiver can be turned on / off under software control. Further
information about the nRF2401 chip can be found at our website http://www.nordicsemi.no.
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PRODUCT SPECIFICATION
nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
3
I/O PORTS
The nRF24E1 have two IO ports located at the default locations for P0 and P1 in standard
8051, but the ports are fully bi-directional CMOS and the direction of each pin is controlled
by a _DIR and an _ALT bit for each bit as shown in the table below.
Pin
Default function
DIN0
P1.2
DIO0
P1.0
DIO1
P1.1
DIO2
P0.02
DIO3
P0.1
DIO4
P0.2
DIO5
P0.3
DIO6
P0.4
DIO7
P0.5
DIO8
P0.6
DIO9
P0.7
Table 3-1 : Port functions
Alternate=1
T2 (timer2 input)
SPI_CTRL=01
SPI_DI
SPI_SCK
SPI_DO
EEPROM_CSN
RXD (UART)
TXD (UART)
INT0_N (interrupt)
INT1_N (interrupt)
T0 (timer0 input)
T1 (timer1 input)
PWM
3.1 I/O port behavior during RESET
During the period the internal reset is active (regardless of whether or not the clock is
running), all the port pins are configured as inputs. When program execution starts, the DIO
ports are still configured as inputs and the program will need to set the _ALT and/or the
_DIR register for the pins that should be used as outputs.
3.2 Port 0 (P0)
P0_ALT and P0_DIR control the P0 port function in that order of priority. If the alternate
function for port p0.n is set (by P0_ALT.n = 1) the pin will be input or output as required by
the alternate function (UART, external interrupt, timer inputs or PWM output), except that
the UART RXD direction will still depend on P0_DIR.1.
To use INT0_N or INT1_N, the corresponding alternate function must be activated,
P0_ALT.3 / P0_ALT.4
When the P0_ALT.n is not set, bit ‘n’ of the port is a GPIO function with the direction
controlled by P0_DIR.n.
P0.0 is always a GPIO. It will be activated by the default boot loader after reset and should
be connected to the CSN of the boot flash.
2
Reserved for use as EEPROM_CSN, works as GPIO P0.0 independent of the “Alternate setting”
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PRODUCT SPECIFICATION
nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
Pin
10
P0.0
P0.0
Out
(DIO2)
P0.1
RXD
Out
(DIO3)
P0.2
TXD
Out
(DIO4)
P0.3
INT0_N In
(DIO5)
P0.4
INT1_N In
(DIO6)
P0.5
T0
In
(DIO7)
P0.6
T1
In
(DIO8)
P0.7
PWM
Out
(DIO9)
Table 3-2 : Port 0 (P0) functions
Data in P0_ALT.n,P0_DIR.n
11
00
P0.0
In
P0.0
Out
P0.0
In
RXD
In
P0.1
Out
P0.1
In
TXD
Out
P0.2
Out
P0.2
In
INT0_N
In
P0.3
Out
P0.3
In
INT1_N
In
P0.4
Out
P0.4
In
T0
In
P0.5
Out
P0.5
In
T1
In
P0.6
Out
P0.6
In
PWM
Out
P0.7
Out
P0.7
In
01
Port 0 is controlled by SFR-registers 0x80, 0x94 and 0x95 listed in the table below.
Addr
SFR
(hex)
80
94
R/W #bit
R/W
R/W
8
8
Init
value
(hex)
FF
FF
Name
Function
P0
P0_DIR
Port 0, pins DIO9 to DIO2
Direction for each bit of Port 0
0: Output, 1: Input
Direction is overridden if alternate function is
selected for a pin.
95
R/W
8
00
P0_ALT Select alternate functions for each pin of P0,
if corresponding bit in P0_ALT is set, as
listed in Table 3-2 : Port 0 (P0) functions,
P0.0 has no alternate function,as it is
intended as CS for external boot flash
memory. It will function as a GPIO bit
regardless of P0_ALT.0
Table 3-3 : Port 0 control and data SFR-registers
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PRODUCT SPECIFICATION
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3.3 Port 1 (P1 or SPI port)
The P1 port consists of only 3 pins, one of which is an hardwired input. The function is
controlled by SPI_CTRL.
When SPI_CTRL is 01, the port is used as a SPI master port. The GPIO bits in port P0
may be used as chip select(s). For timing diagram, please see Figure 3-1 : SPI interface
timing.
When not used as SPI port, P0_ALT.0 will force P1.0 to be the timer T2 input, P1.1 is
now a GPIO. When P0_ALT.0 is 0, also P1.0 is a GPIO.
P1.2 (DIN0) is always an input.
Pin
SPI_CTRL =
01
In
SPI_CTRL != 01
P1_ALT.n = 0
P1_DIR.n = 0
P1_DIR.n = 1
P1.0
In
P1.0
Out
In3
P1.1
In
P1.1
Out
In
P1.2
In
P1.2
In
P1_ALT.n = 1
P1.0
SCK
Out
T2
(DIO0)
P1.1
SDO
Out
P1.1
(DIO1)
P1.2
SDI
In
P1.2
(DIN0)
Table 3-4 : Port 1 (P1) functions
Port 1 is controlled by SFR-registers 0x90, 0x96 and 0x97, and only the 3 lower bits of the
registers are used.
Addr
SFR
(hex)
90
96
R/W #bit
R/W
R/W
3
3
Init
value
(hex)
FF
FF
Name
Function
P1
P1_DIR
Port 1, pins DIN0, DIO1 and DIO0
Direction for each bit of Port 1
0: Output, 1: Input
Direction is overridden if alternate function is
selected for a pin, or if SPI_CTRL=01.
bit0, DIN0 is always input.
3
P1.1 is actually under control of P1_DIR.1 even when P1_ALT.1 is 1, since there is no alternate
function for this pin.
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PRODUCT SPECIFICATION
nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
97
R/W
3
00
P1_ALT
Select alternate functions for each pin of P1
if corresponding bit in P1_ALT is set, as listed
in Table 3-4 : Port 1 (P1) functions
If SPI_CTRL is ‘01’, the P1 port is used as
SPI master data and clock :
2 -> SDI – input to nRF24E1 from slave
1 -> SDO – output from nRF24E1 to slave
0 -> SCK – output from nRF24E1 to slave
Table 3-5 : Port 1 control and data SFR-registers
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P1 may also be configured as a SPI master port , and is then controlled by the 3 SFR
registers 0xB2, 0xB3, 0xB4 as shown in the table below.
Addr
SFR
(hex)
B2
B3
R/W #bit
R/W
R/W
8
2
Init Name
(hex
)
0
SPI_DATA
0
SPI_CTRL
Function
SPI data input/output
00 -> SPI not used no clock generated
01 -> SPI connected to port P1 (as for booting)
another GPIO must be used as chip select
(see also Table 3-4 : Port 1 (P1) functions)
10 -> SPI connected to RADIO
transmitter/receiver 1 for TX or RX or for
transceiver configuration
11 -> SPI connected to RADIO receiver 2 for RX
Chip select is a bit of RADIO register (see
Table 4-2 : RADIO register )
B4
R/W
2
0
SPICLK
Divider factor from CPU clock to SPI clock
00: 1/8 of CPU clock frequency
01: 1/16 of CPU clock frequency
10: 1/32 of CPU clock frequency
11: 1/64 of CPU clock frequency
The CPU clock is the oscillator generated clock
described in Crystal Specification page 108
Table 3-6 : SPI control and data SFR-registers
3.3.1 SPI interface operation
Whenever SPI_DATA register is written to, a sequence of 8 pulses is started on SCK,
and the 8 bits of SPI_DATA register are clocked out on SDO with msb first.
Simultaneously 8 bits from SDI are clocked into SPI_DATA register. Ouput data is shifted
on negedge SCK, and input data is read on posedge SCK. This is illustrated in Figure 3-1 :
SPI interface timing. When the 8 bits are done, SPI_READY interrupt (EXIF.5) goes
active, and the 8 bits from SDI may be read from SPI_DATA register. The EXIF.5 bit must
be cleared before starting another SPI transaction by writing to SPI_DATA register again.
SCK, SDO and SDI may be external pins or internal signals, as defined in SPI_CTRL
register.
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PRODUCT SPECIFICATION
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End of
write to
SPI_DATA
register
SCK
SDO
MSB
LSB
SDI
MSB
LSB
SPI_READY
interrupt
thSDI
tdSCK
tdSDO
t cSCK
tsSDI
Figure 3-1 : SPI interface timing
tcSCK : SCK cycle time, as defined by SPICLK register.
tdSCK : time from writing to SPI_DATA register to first SCK pulse,
tdSCK = tcSCK / 2
tdSDO : delay from negedge SCK to new SDO output data, may vary from
-40ns to 40ns
tsSDI : SDI setup time to posedge SCK, tsSDI > 45ns.
thSDI : SDI hold time to posedge SCK, thSDI > 0ns.
tdready : time from last SCK pulse to SPI_READY interrupt goes active
tdready = 7 CPU clock cycles
Note that the above delay, setup and hold time numbers only apply for SPI
connected to Port 1; as when SPI is connected to the Radio, SCK,SDO,SDI are all
internal signals, not visible to the user.
Minimum time between two consecutive SPI transactions will be :
8.5 tcSCK + tdready + tSW
where tSW is the time taken by the software to process SPI_READY interrupt, and write to
SPI_DATA register.
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tdready
PRODUCT SPECIFICATION
nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
4
nRF2401 2.4GHz TRANSCEIVER SUBSYSTEM
4.1 RADIO port (Port 2)
The transceiver is controlled by the RADIO port. The RADIO port uses the address
normally used by port P2 in standard 8051. However since the radio transceiver is on chip,
the port is not bi-directional. The power on default values in the port “latch” also differs from
traditional 8051 to match the requirements of the radio transceiver subsystem.
Operation of the transceiver is controlled by SFR registers RADIO and SPI_CTRL:
Addr
SFR
(hex)
A0
B3
R/W #bit
R/W
8
Init
value
(hex)
80
R/W
2
0
Name
Function
RADIO
General purpose IO for interface to
nRF2401 radio transceiver subsystem
SPI_CTRL
00 -> SPI not used
01 -> SPI connected to port P1 (boot)
10 -> SPI connected to nRF2401 CH1
11 -> SPI connected to nRF2401 RX
CH2
Table 4-1 : nRF2401 2.4GHz transceiver subsystem control registers - SFR 0xA0 and
0xB3
The bits of the RADIO register correspond to similar pins of the nRF2401 single chip, as
shown in Table 4-2 : RADIO register . In the documentation the pin names are used, so
please note that setting or reading any of these nRF2401 pins, means to write or read the
RADIO SFR register accordingly. Please also note that in the transceiver documentation
the notation MCU means the onchip 8051 compatible microcontroller.
RADIO register bit
Read :
7: 0 (not used)
6: DR2, data ready from receiver 2 (available also
as interrupt)
5: CLK2, clock for receiver 2 data out
4: DOUT2, data out from receiver 2
3: 0 (not used)
2: DR1, data ready from receiver 1 (available also
as interrupt)
1: CLK1, clock for receiver 1 data out
corresponding pin name on
single chip nRF2401
2.4GHz Transceiver
DR2
CLK2
DOUT2
DR1
CLK1
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PRODUCT SPECIFICATION
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0: DATA, data out from receiver 1
DATA
Write :
7: PWR_UP, power on radio
PWR_UP
6: CE, Activate RX or TX mode
CE
5: CLK2, clock for receiver 2 data out
CLK2
4: Not used
3: CS, Chip select configuration mode
CS
2: Not used
1: CLK1, clock for data input or receiver 1 data out
CLK1
0: DATA, configuration or TX data input
DATA
Table 4-2 : RADIO register - SFR 0xA0, default initial data value is 0x80.
Note : Some of the pins are overridden when SPI_CTRL=1x, see Table 4-3 : Transceiver
SPI interface.
4.1.1 Controlling the transceiver via SPI interface.
It is more convenient to use the built-in SPI interface to do the most common transceiver
operations as RF configuration and ShockBurst™ RX or TX. Please see Table 3-6 : SPI
control and data SFR-registers for use of SPI interface. The radio port will be connected in
different ways to the SPI hardware when SPI_CTRL is ‘1x’. When SPI_CTRL is ‘0x’, all
radio pins are connected directly to their respective port pins.
SPI signal
SPI_CTRL=10 (binary)
CS
RADIO_wr.6 (CE) for ShockBurst™
(active high)
RADIO_wr.3 (CS) for Configuration
SCK
nRF2401/CLK1
SDI
nRF2401/DATA
SDO
nRF2401/DATA
ShockBurst™ data
RADIO_rd.2 (DR1)
ready
Table 4-3 : Transceiver SPI interface.
SPI_CTRL=11
RADIO_wr.6 (CE)
nRF2401/CLK2
nRF2401/DOUT2
not used
RADIO_rd.6 (DR2)
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PRODUCT SPECIFICATION
nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
SPI_CTRL
RADIO register
nRF2401
Tranceiver
read bitno
write
-------------------------7 PWR_UP
DR2
6
CE
CLK2 5
CLK2
DOUT2 4
3
CS
DR1
2
CLK1 1
CLK1
DATA 0
DATA
input
output
-----------------------PWR_UP
CE
DR2
CLK2
CLK2
DOUT2
CS
DR1
CLK1
CLK1
DATA
DATA
3
2
2
SPI
interface
MUX
MUX
MUX
SCK
SDO
SDI
MUX
2
3
Figure 4-1 : Transceiver interface
4.1.2 RADIO port behavior during RESET
During the period the internal reset is active (regardless of whether or not the clock is
running), the RADIO outputs that control the nRF2401 transceiver subsystem are forced to
their respective default values (RADIO.3=0 (CS), RADIO.6=0 (CE) RADIO.7=1
(PWR_UP)). When program execution starts, these ports will remain at those default levels
until the programmer actively changes them by writing to the RADIO register.
4.2 Modes of operation
4.2.1 Overview
The nRF2401 subsystem can be set in the following main modes depending on three control
pins:
Mode
Active (RX/TX)
Configuration
Stand by
Power down
PWR_UP
CE
CS
1
1
1
0
1
0
0
X
0
1
0
X
Table 4-4 nRF2401 subsystem main modes
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PRODUCT SPECIFICATION
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4.2.2
Active modes
The nRF2401 subsystem has two active (RX/TX) modes:
•
•
ShockBurst™
Direct Mode (not supported by nRF24E1)
The device functionality in these modes is decided by the content of a configuration word.
This configuration word is presented in the configuration section. Please note that Direct
mode is not supported, as this will require a more powerful CPU than 8051.
4.2.3 ShockBurst™
The ShockBurst™ technology uses on-chip FIFO to clock in data at a low data rate and
transmit at a very high rate thus enabling extremely power reduction.
When operating the nRF2401 subsystem in ShockBurst™, you gain access to the high data
rates (1 Mbps) offered by the 2.4 GHz band without the need of a costly, high-speed
microcontroller (MCU) for data processing.
By putting all high speed signal processing related to RF protocol on-chip, the nRF24E1
offers the following benefits:
•
•
•
Highly reduced current consumption
Lower system cost (facilitates use of less expensive microcontroller)
Greatly reduced risk of ‘on-air’ collisions due to short transmission time
The nRF2401 subsystem can be programmed using a simple 3-wire interface where the
data rate is decided by the speed of the CPU.
By allowing the digital part of the application to run at low speed while maximizing the data
rate on the RF link, the ShockBurst™ mode reduces the average current consumption in
applications considerably.
4.2.3.1 ShockBurst™ principle
When the nRF2401 subsystem is configured in ShockBurst™, TX operation is conducted in
the following way (10 kbps for the example only).
10 kbps effective
8051
MCU
nRF2401
subsyst.
FIFO
ShockBurstTM
1Mbps
Figure 4-2Clocking in data with CPU and sending with ShockBurst technology
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PRODUCT SPECIFICATION
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Without ShockBurstTM, running at speed dictated by 10Kbs MCU
10mA period
10mA period
0
20
40
60
10Kbs MCU with ShockBurst TM
80
100
120
140
160
180
200
220
Time mS
Figure 4-3 RF Current consumption with & without ShockBurst technology
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PRODUCT SPECIFICATION
nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
NO
nRF2401 in
ShockBurst TM
TX (CE=hi)?
YES
Data content of registers:
uController
Loading ADDR
and PAYLOAD
data
ADDR
PAYLOAD
Maximum 256 bits
nRF2401
Calculating CRC
ADDR
PAYLOAD
CRC
NO
CE=Low?
YES
nRF2401
Adding Preamble
nRF2401
Sending
ShockBurst TM
Package
(250 or 1000kbps)
YES
Preamble
ADDR
PAYLOAD
CRC
Input FIFO not Empty
NO
Sending
completed?
Figure 4-4 Flow Chart ShockBurst™ Transmit of nRF2401 subsystem
4.2.3.2 ShockBurst™ Transmit:
4.2.3.2.1 CPU interface pins: CE, CLK1, DATA
1. When the application CPU has data to send, set CE high. This activates
nRF2401 on-board data processing.
2. The address of the receiving node (RX address) and payload data is clocked
into the nRF2401 subsystem. The application protocol or CPU sets the speed
L -> H to start A/D conversion.
This bit is internally synchronized to the ADC clock
Ignored if ADCRUN is set..
Set to have the A/D converter run continuously
CSTARTN is ignored in this case
Set to 0 to put A/D converter in power down state
Select reference for A/D converter
0: Use internal band gap reference (nominally 1.22V)
1: Use external pin AREF for reference
Ignored if ADCSEL=8.
Select input AIN0 to AIN7
ADCSEL=8 will select internal VDD/3, and also automatically
select internal bandgap reference
For n=0..7, ADCSEL=n will select input pin AINn
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Table 5-1 : ADCCON register, SFR 0xA1, default initial data value is 0x80.
5.2.2
Bit(s)
7
ADCSTATIC register, SFR 0xA4
Function
Enable differential measurements, AIN0 must be used as
inverting input and one of the other inputs AIN1 to AIN7, as
selected by ADCSEL, must be used as noninverting input.
6
SLEEP
Set A/D converter in a reduced power mode
5
CLK8
0 : ADCCLK frequency = CPU clock divided by 32
1 : ADCCLK frequency = CPU clock divided by 8
4–2
ADCBIAS
Control A/D converter bias current
No need to change for nRF24E1 operation
1-0
ADCRES
Select A/D converter resolution
00: 6-bit, result in ADCDATAH 5-0
01: 8-bit, result in ADCDATAH
10: 10-bit, result in ADCDATAH,ADCDATAL.7-6
11: 12-bit, result in ADCDATAH,ADCDATAL.7-4
Table 5-2 : ADCSTATIC register, SFR 0xA4, default initial data value is 0x0A.
5.2.3
Bit(s)
7-0
5.2.4
Bit(s)
7-4
Name
DIFFM
ADCDATAH register, SFR 0xA2
Name
ADCDATAH
Function
Most significant 8 bits of A/D converter result. For 6-bit
conversions ADCDATAH.7-6 is ‘00’
ADCDATAL register, SFR 0xA3
Name
ADCDATAL
Function
Least significant part of A/D converter result when resolution
is 12 or 10 bits, leftjustified. For 10-bit conversions
ADCDATAH.5-4 is ‘00’
3
not used
2
ADCUF
Underflow in conversion. Data is all 0’s
1
ADCOF
Overflow in conversion. Data is all 1’s
0
ADCRNG
Overflow or underflow in conversion
(ADCUF | ADCOF)
Table 5-3 : ADC data SFR-registers, SFR 0xA2 and 0xA3.
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5.3 A/D converter usage
5.3.1 End of conversion.
A signal ADC_EOC is available in the EXIF.4 bit (Interrupt 2 flag) and it is set to 1 by A/D
converter when a conversion (single step or continuous mode) is completed, see Table 7-4
: EXIF Register – SFR 0x91. For timing of ADC_EOC, see Figure 5-3 and Figure 5-4
5.3.2 Measurements with external reference
When EXTREF (ADCCON.4) is set to 1 and ADCSEL (ADCCON.3-0) selects an input
AIN i ( i.e. AIN 0 to AIN 7), the result in ADCDATA is directly proportional to the ratio
between the voltage on the selected input, and the voltage on pin AREF.
AIN i voltage = AREF voltage * ADCDATA / 2**N
Where N is the number of bits set in ADCRES (ADCSTATIC.1-0) and ADCDATA is the
resulting bits in ADCDATAH (and ADCDATAL if N > 8).
For differential measurements a simular equation apply :
(AIN i - AIN 0)voltage = AREF voltage * (ADCDATA -2**(N-1)) / 2**N
This mode of operation is normally selected for sources where the voltage is depending on
the supply voltage (or another variable voltage), like shown in Figure 5-2 below. The
resistor R1 is selected to keep AREF = 1.5V for the maximum VDD voltage.
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SUPPLY
R1
VDD
AREF
nRF24E1
R2
AIN0
R3
AIN1
Figure 5-2 Typical use of A/D with 2 ratiometric inputs
5.3.3 Measurements with internal reference
When EXTREF (ADCCON.4) is set to 0 and ADCSEL (ADCCON.3-0) selects an input
AIN i (i.e. AIN 0 to AIN 7), the result in ADCDATA is directly proportional to the ratio
between the voltage on the selected input, and the internal bandgap reference (nominally
1.22V).
if single ended input : AINi voltage = 1.22 V * ADCDATA / 2**N
if differential input : (AINi - AIN 0) voltage = 1.22 V * (ADCDATA -2**(N-1)) / 2**N
Where N is the number of bits set in ADCRES (ADCSTATIC.1-0) and ADCDATA is the
result bits in ADCDATAH (and ADCDATAL if N > 8).
This mode of operation is normally selected for sources where the voltage is not depending
on the supply voltage.
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5.3.4 Supply voltage measurement
When ADCSEL (ADCCON.3-0) is set to 8, the ADC will use the internal bandgap
reference (nominally 1.22V), and the input is 1/3 of the voltage on the VDD pins. The result
in ADCDATA is thus directly proportional to the VDD voltage.
VDD voltage = 3.66 V * ADCDATA / 2**N
Where N is the number of bits set in ADCRES (ADCSTATIC.1-0) and ADCDATA is the
result bits in ADCDATAH (and ADCDATAL if N > 8).
5.4 A/D Converter timing
ADCCLK
CSTARTN
input signal
sampled
tConv
ADC_EOC
ADCDATA
any previously converted value is held until
new ADC_EOC
Figure 5-3 : Timing diagram single step conversion.
ADCRUN=0, and conversion is started at first posedge ADCCLK after CSTARTN has
gone high. A pulse is generated on ADC_EOF when the converted value is available on the
ADCDATA bus. Conversion time tConv depends on resolution,
tConv = N/2 + 3 clock cycles, where N is number of resolution bits. In the figure a 10 bit
conversion is shown. Minimum width of a CSTARTN pulse is 1 clock cycle. If a new
CSTARTN pulse comes before previous conversion has finished, the previous conversion
will be aborted.
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ADCCLK
input signal
sample
n
n+1
n+2
tConv
ADC_EOC
tCycle
ADCDATA
sample n-1
sample n
Figure 5-4 : Timing diagram continuous mode conversion.
ADCRUN=1, and CSTARTN is ignored. Cycle time tCycle is the time between each
conversion. tCycle = N/2 +1 clock cycles, where N is number of resolution bits. The figure is
showing 10 bit conversions.
5.5 Analog interface guidelines
The input impedance of analog inputs should preferably be in range 100-1000 O, and in any
case be less than 10 kO. Small capacitors on inputs (e.g. 200pF) are recommended for
decoupling, see also Figure 15-1 for application example.
If AIN inputs goes beyond the selected reference voltage, the ADC will clip and the result
will be the maximum code. Absolute maximum for any AIN voltage is 2.0V.
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PRODUCT SPECIFICATION
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6
PWM
The nRF24E1 PWM output is a one-channel PWM with a 2 register interface. The first
register, PWMCON, enables PWM function and PWM period length, which is the number
of clock cycles for one PWM period, as shown in the table below. The other register,
PWMDUTY, controls the duty cycle of the PWM output signal. When this register is
written, the PWM signal will change immediately to the new value. This can result in 4
transitions within one PWM period, but the transition period will always have a “DC value”
between the “old” sample and the “new” sample.
The table shows how PWM frequency (or period length) and PWM duty cycle are
controlled by the settings in the two PWM SFR-registers. For a crystal frequency of 16
MHz, PWM frequency range will be about 1-253 kHz.
PWMCON[7:6]
00
PWM frequency
PWMDUTY
(duty cycle)
0 (PWM module inactive)
0
1
63 ⋅ (PWMCON [5 : 0] + 1)
1
f XO ⋅
127 ⋅ ( PWMCON [5 : 0] + 1)
1
f XO ⋅
255 ⋅ ( PWMCON [5 : 0] + 1)
PWMDUTY [5 : 0]
63
PWMDUTY [6 : 0]
127
PWMDUTY
255
f XO ⋅
01
10
11
PWM is controlled by SFR 0xA9 and 0xAA.
Addr
SFR
(hex)
A9
AA
R/W #bit
Init
(hex)
Name
Function
PWM control register
7-6: Enable / period length select
00: Disable PWM
01: Period length is 6 bit
10: Period length is 7 bit
11: Period length is 8 bit
5-0: PWM frequency prescale factor
(see table above)
PWM duty cycle (6 to 8 bits according
to period length)
R/W
8
0
PWMCON
R/W
8
0
PWMDUTY
Table 6-1 : PWM control registers - SFR 0xA9 and 0xAA
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7
INTERRUPTS
nRF24E1 supports the following interrupt sources:
Interrupt signal
INT0_N
Description
External interrupt, active low, configurable as edge-sensitive or levelsensitive, at Port P0.3
TF0
Timer 0 interrupt
INT1_N
External interrupt, active low, configurable as edge-sensitive or levelsensitive, at Port P0.4
TF1
Timer 1 interrupt
TF2 or EXF2
Timer 2 interrupt
TI or RI
Receive/transmit interrupt from Serial Port
int2
Internal ADC_EOC (end of AD conversion) interrupt
int3
Internal SPI_READY interrupt
int4
Internal RADIO.DR1 interrupt (a packet is ready from receiver 1)
int5
Internal RADIO.DR2 interrupt (a packet is ready from receiver 2)
wdti
Internal RTC wakeup timer interrupt
Table 7-1 : nRF24E1 interrupt sources
7.1 Interrupt SFRs
The following SFRs are associated with interrupt control:
- IE – SFR 0xA8 ( Table 7-2)
- IP – SFR 0xB8 ( Table 7-3)
- EXIF – SFR 0x91 ( Table 7-4)
- EICON – SFR 0xD8 ( Table 7-5)
- EIE – SFR 0xE8 ( Table 7-6)
- EIP – SFR 0xF8 ( Table 7-7)
The IE and IP SFRs provide interrupt enable and priority control for the standard
interrupt unit, as with industry standard 8051. The EXIF, EICON, EIE, and EIP
registers provide flags, enable control, and priority control for the extended
interrupt unit.
Table 7-2 explains the bit functions of the IE register.
Bit
IE.7
IE.6
IE.5
Function
EA - Global interrupt enable. Controls masking of all interrupts. EA = 0
disables all interrupts (EA overrides individual interrupt enable bits). When EA
= 1, each interrupt is enabled or masked by its individual enable bit.
Reserved. Read as 0.
ET2 - Enable Timer 2 interrupt. ET2 = 0 disables Timer 2 interrupt (TF2).
ET2 = 1 enables interrupts generated by the TF2 or EXF2 flag.
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IE.4
ES - Enable Serial Port interrupt. ES = 0 disables Serial Port interrupts (TI
and RI). ES = 1 enables interrupts generated by the TI or RI flag.
IE.3
ET1 - Enable Timer 1 interrupt. ET1 = 0 disables Timer 1 interrupt (TF1).
ET1 = 1 enables interrupts generated by the TF1 flag.
IE.2
EX1 - Enable external interrupt 1. EX1 = 0 disables external interrupt 1
(INT1_N). EX1 = 1 enables interrupts generated by the INT1_N pin.
IE.1
ET0 - Enable Timer 0 interrupt. ET0 = 0 disables Timer 0 interrupt (TF0).
ET0 = 1 enables interrupts generated by the TF0 flag.
IE.0
EX0 - Enable external interrupt 0. EX0 = 0 disables external interrupt 0
(INT0_N). EX0 = 1 enables interrupts generated by the INT0_N pin.
Table 7-2 : IE Register – SFR 0xA8
Table 7-3 explains the bit functions of the IP register.
Bit
IP.7
IP.6
IP.5
Function
Reserved. Read as 1.
Reserved. Read as 0.
PT2 - Timer 2 interrupt priority control. PT2 = 0 sets Timer 2 interrupt (TF2)
to low priority. PT2 = 1 sets Timer 2 interrupt to high priority.
IP.4
PS - Serial Port interrupt priority control. PS = 0 sets Serial Port interrupt (TI
or RI) to low priority. PS = 1 sets Serial Port interrupt to high priority.
IP.3
PT1 - Timer 1 interrupt priority control. PT1 = 0 sets Timer 1 interrupt (TF1)
to low priority. PT1 = 1 sets Timer 1 interrupt to high priority.
IP.2
PX1 - External interrupt 1 priority control. PX1 = 0 sets external interrupt 1
(INT1_N) to low priority. PT1 = 1 sets external interrupt 1 to high priority.
IP.1
PT0 - Timer 0 interrupt priority control. PT0 = 0 sets Timer 0 interrupt (TF0)
to low priority. PT0 = 1 sets Timer 0 interrupt to high priority.
IP.0
PX0 - External interrupt 0 priority control. PX0 = 0 sets external interrupt 0
(INT0_N) to low priority. PT0 = 1 sets external interrupt 0 to high priority.
Table 7-3 : IP Register – SFR 0xB8
Table 7-4 explains the bit functions of the EXIF register.
Bit
EXIF.7
EXIF.6
Function
IE5 - Interrupt 5 flag. IE5 = 1 indicates that a rising edge was detected on the
RADIO.DR2 signal.(see ch. 5.1.RADIO) IE5 must be cleared by software.
Setting IE5 in software generates an interrupt, if enabled.
IE4 - Interrupt 4 flag. IE4 = 1 indicates that a rising edge was detected on the
RADIO.DR1 signal.(see ch. 5.1.RADIO) IE4 must be cleared by software.
Setting IE4 in software generates an interrupt, if enabled.
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EXIF.5
IE3 - Interrupt 3 flag. IE3 = 1 indicates that the internal SPI module has sent
or received 8 bits, and is ready for a new command. IE3 must be cleared by
software. Setting IE3 in software generates an interrupt, if enabled.
EXIF.4
IE2 - Interrupt 2 flag. IE2 = 1 indicates that a rising edge was detected on the
ADC_EOC signal. (see ch.5.3.1 End of conversion.) IE2 must be cleared by
software. Setting IE2 in software generates an interrupt, if enabled.
EXIF.3
Reserved. Read as 1.
EXIF.2-0 Reserved. Read as 0.
Table 7-4 : EXIF Register – SFR 0x91
Table 7-5 explains the bit functions of the EICON register.
Bit
EICON.7
EICON.6
EICON.5
EICON.4
EICON.3
Function
Not used.
Reserved. Read as 1.
Reserved. Read as 0.
Reserved. Read as 0.
WDTI - RTC wakeup timer interrupt flag. WDTI = 1 indicates a wakeup
timer interrupt was detected. WDTI must be cleared by software before
exiting the interrupt service routine. Otherwise, the interrupt occurs again.
Setting WDTI in software generates a wakeup timer interrupt, if enabled.
Reserved. Read as 0.
EICON.20
Table 7-5 : EICON Register – SFR 0xD8
Table 7-6 explains the bit functions of the EIE register.
Bit
EIE.7-5
EIE.4
Function
Reserved. Read as 1.
EWDI - Enable RTC wakeup timer interrupt. EWDI = 0 disables wakeup
timer interrupt (wdti). EWDI = 1 enables interrupts generated by wakeup.
EIE.3
EX5 - Enable interrupt 5. EX5 = 0 disables interrupt 5 (RADIO.DR2). EX5
= 1 enables interrupts generated by the RADIO.DR2 signal.
EIE.2
EX4 - Enable interrupt 4. EX4 = 0 disables interrupt 4 (RADIO.DR1). EX4
= 1 enables interrupts generated by the RADIO.DR1 signal.
EIE.1
EX3 - Enable interrupt 3. EX3 = 0 disables interrupt 3 (SPI_READY). EX3
= 1 enables interrupts generated by the SPI_READY signal.
EIE.0
EX2 - Enable interrupt 2. EX2 = 0 disables interrupt 2 (ADC_EOC). EX2 =
1 enables interrupts generated by the ADC_EOC signal.
Table 7-6 : EIE Register – SFR 0xE8
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Table 7-7 explains the bit functions of the EIP register.
Bit
EIP.7-5
EIP.4
Function
Reserved. Read as 1.
PWDI - RTC wakeup timer interrupt priority control. WDPI = 0 sets wakeup
timer interrupt (wdti) to low priority. PS = 1 sets wakeup timer interrupt to
high priority.
EIP.3
PX5 - interrupt 5 priority control. PX5 = 0 sets interrupt 5 (RADIO.DR2) to
low priority. PX5 = 1 sets interrupt 5 to high priority.
EIP.2
PX4 - interrupt 4 priority control. PX4 = 0 sets interrupt 4 (RADIO.DR1) to
low priority. PX4 = 1 sets interrupt 4 to high priority.
EIP.1
PX3 - interrupt 3 priority control. PX3 = 0 sets interrupt 3 (SPI_READY) to
low priority. PX3 = 1 sets interrupt 3 to high priority.
EIP.0
PX2 - interrupt 2 priority control. PX2 = 0 sets interrupt 2 (ADC_EOC) to
low priority. PX2 = 1 sets interrupt 2 to high priority.
Table 7-7 : EIP Register – SFR 0xF8
7.2 Interrupt Processing
When an enabled interrupt occurs, the CPU vectors to the address of the interrupt
service routine (ISR) associated with that interrupt, as listed in Table 7-8. The
CPU executes the ISR to completion unless another interrupt of higher priority
occurs. Each ISR ends with an RETI (return from interrupt) instruction. After
executing the RETI, the CPU returns to the next instruction that would have been
executed if the interrupt had not occurred.
Interrupt
Description
INT0_N
TF0
INT1_N
TF1
TI or RI
External interrupt 0
Timer 0 interrupt
External interrupt 1
Timer 1 interrupt
Serial Port transmit or
receive
Timer 2 interrupt
ADC_EOC interrupt
SPI_READY interrupt
RADIO.DR1 interrupt
RADIO.DR2 interrupt
RTC wakeup timer
TF2 or EXF2
int2
int3
int4
int5
wdti
Natural Priority
(lowest number
gives highest
priority)
1
2
3
4
5
Interrupt
Vector
6
8
9
10
11
12
0x2B
0x43
0x4B
0x53
0x5B
0x63
0x03
0x0B
0x13
0x1B
0x23
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interrupt
Table 7-8 : Interrupt Natural Vectors and Priorities
An ISR can only be interrupted by a higher priority interrupt. That is, an ISR for a
low-level interrupt can be interrupted only by a high-level interrupt. The CPU
always completes the instruction in progress before servicing an interrupt. If the
instruction in progress is RETI, or a write access to any of the IP, IE, EIP, or EIE
SFRs, the CPU completes one additional instruction before servicing the
interrupt.
7.3 Interrupt Masking
The EA bit in the IE SFR (IE.7) is a global enable for all interrupts. When EA = 1,
each interrupt is enabled/masked by its individual enable bit. When EA = 0, all
interrupts are masked. Table 7-9 provides a summary of interrupt sources, flags,
enables, and priorities.
Interrupt
INT0_N
TF0
INT1_N
TF1
TI or RI
Description
External interrupt 0
Timer 0 interrupt
External interrupt 1
Timer 1 interrupt
Serial Port transmit or
receive
Flag
TCON.1
TCON.5
TCON.3
TCON.7
SCON.0 (RI),
SCON.1 (TI)
Enable
IE.0
IE.1
IE.2
IE.3
IE.4
Control
IP.0
IP.1
IP.2
IP.3
IP.4
TF2 or EXF2
Timer 2 interrupt
T2CON.7 (TF2),
T2CON.6 (EXF2)
EXIF.4
EXIF.5
EXIF.6
EXIF.7
EICON.3
IE.5
IP.5
EIE.0
EIE.1
EIE.2
EIE.3
EIE.4
EIP.0
EIP.1
EIP.2
EIP.3
EIP.4
int2
int3
int4
int5
wdti
ADC_EOC interrupt
SPI_READY interrupt
RADIO.DR1 interrupt
RADIO.DR2 interrupt
RTC wakeup timer
interrupt
Table 7-9 : Interrupt Flags, Enables, and Priority Control
7.4 Interrupt Priorities
There are two stages of interrupt priority assignment: interrupt level and natural
priority. The interrupt level (high, or low) takes precedence over natural priority.
All interrupts can be assigned either high or low priority. In addition to an
assigned priority level (high or low), each interrupt has a natural priority, as listed
in Table 7-8. Simultaneous interrupts with the same priority level (for example,
both high) are resolved according to their natural priority. For example, if
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INT0_N and int2 are both programmed as high priority, INT0_N takes
precedence. Once an interrupt is being serviced, only an interrupt of higher
priority level can interrupt the service routine of the interrupt currently being
serviced.
7.5 Interrupt Sampling
The internal timers and serial port generate interrupts by setting their respective
SFR interrupt flag bits. The CPU samples external interrupts once per instruction
cycle, at the rising edge of CPU_clk at the end of cycle C4.
The INT0_N and INT1_N signals are both active low and can be programmed
through the IT0 and IT1 bits in the TCON SFR to be either edge-sensitive or
level-sensitive. For example, when IT0 = 0, INT0_N is level-sensitive and the
CPU sets the IE0 flag when the INT0_N pin is sampled low. When IT0 = 1,
INT0_N is edge-sensitive and the CPU sets the IE0 flag when the INT0_N pin is
sampled high then low on consecutive samples. To ensure that edge-sensitive
interrupts are detected, the corresponding ports should be held high for four
clock cycles and then low for four clock cycles. Level-sensitive interrupts are
not latched and must remain active until serviced.
7.6 Interrupt Latency
Interrupt response time depends on the current state of the CPU. The fastest
response time is five instruction cycles: one to detect the interrupt, and four to
perform the LCALL to the ISR.The maximum latency (thirteen instruction
cycles) occurs when the CPU is currently executing an RETI instruction followed
by a MUL or DIV instruction. The thirteen instruction cycles in this case are: one
to detect the interrupt, three to complete the RETI, five to execute the DIV or
MUL, and four to execute the LCALL to the ISR.
For the maximum latency case, the response time is 13 x 4 =52clock cycles.
7.7 Interrupt Latency from Power Down Mode.
nRF24E1 may be set into Power Down Mode by writing 0x2 or 0x3 to SFR 0xB6,
register CK_CTRL. The CPU will then perform a controlled shutdown of clock and power
regulator. The system can only be restarted from pins INT0_N or INT1_N, or an RTC
wakeup or a Watchdog reset. In this case the CPU cannot respond until the clock and
power regulator have restarted, which may take 3 to 4 LP_OSC cycles. This delay may
vary from 0.6ms to 4 ms depending on processing, temperature and supply voltage. In the
same way, the shutdown also takes from 2 to 3 LP_OSC cycles, which will be in the range
of 0.4 - 3ms.
7.8 Single-Step Operation
The nRF24E1 interrupt structure provides a way to perform single-step program
execution. When exiting an ISR with an RETI instruction, the CPU will always
execute at least one instruction of the task program. Therefore, once an ISR is
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entered, it cannot be re-entered until at least one program instruction is executed.
To perform single-step execution, program one of the external interrupts (for
example, INT0_N) to be level-sensitive and write an ISR for that interrupt that
terminates as follows:
JNB TCON.1,$ ;
JB TCON.1,$ ;
RETI ;
wait for high on INT0_N
wait for low on INT0_N
return for ISR
The CPU enters the ISR when INT0_N goes low, then waits for a pulse on
INT0_N. Each time INT0_N is pulsed, the CPU exits the ISR, executes one
program instruction, then re-enters the ISR.
8
WAKEUP TIMER AND WATCHDOG
8.1 Tick calibration
The “TICK” is an interval that is nominally 10ms long. This interval is the unit of resolution
both for the watchdog and the RTC wakeup timer. The LP_OSC clock source of the
“TICK” is very inaccurate, and may vary from 6ms to 30ms depending on processing,
temperature and supply voltage. That means that Watchdog and RTC may not be used for
any accurate timing functions.
The accuracy can be improved by calibrating the TICK value at regular intervals. The
register TICK_DV controls how many LP_OSC periods elapse between each TICK. The
frequency of the LP_OSC (between 1 kHz and 5 kHz) can be measured by timer2 in
capture mode with t2ex enabled (EXEN2=1). The signal connected to t2ex has exactly half
the frequency of LP_OSC. The 16-bit difference between two consecutive captures in
SFR-registers{RCAP2H,RCAP2L} is proportional to the LP_OSC period. For details
about timer2 see ch. 10.8.3 and Figure 10-5 : Timer 2 – Timer/Counter with Capture
TICK is controlled by SFR 0xB5.
Addr
SFR
B5
R/W #bit
R/W
8
Init
hex
1D
Name
Function
TICK_DV
Divider that’s used in generating TICK from
LP_OSC frequency.
fTICK = fLP_OSC / (1 + TICK_DV)
The default value gives a TICK of 10ms
nominal as default.
Table 8-1 : TICK control register - SFR 0xB5
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8.2 RTC Wakeup timer
The RTC is a simple 16 bit down counter that produces an interrupt and reloads
automatically when the count reaches zero. This process is initially disabled, and will be
enabled with the first write to the timer latch. Writing the timer latch will always be followed
by a reload of the counter. The counter may be disabled again by writing a disable opcode
to the control register. Both the latch and the counter value may be read by giving the
respective codes in the control register, see description in Table 8-2
This counter is used for a wakeup sometime in the future (a relative time wakeup call). If
‘N’ is written to the counter, the first wakeup will happen from somewhere between ‘N+1’
and ‘N+2’ “TICK” from the completion of the write, thereafter a new wakeup is issued
every “N+1” "TICK" until the unit is disabled or another value is written to the latch.
The wakeup timer is connected to the WDTI interrupt of the CPU. The programmer may
poll the EICON.3 flag or enable the interrupt. If the oscillator is stopped, the wakeup
interrupt will restart the oscillator regardless of the state of EIE.4 interrupt enable.
The nRF24E1 do not provide any “absolute time functions”. Absolute time functions in
nRF24E1 can well be handled in software since our RAM is continuously powered even
when in sleep mode. There will be an application note with the required code to implement
the complete absolute time function using some 100 bytes of code and 12 IRAM locations
(with 2 alarms).
8.3 Watchdog
The watchdog is activated upon writing 0x08 to its control register SFR 0xAD. It can not be
disabled by any other means than a reset. The watchdog register is loaded by writing a 16bit value to the two 8-bit data registers (SFR 0xAB and 0xAC) and then the writing the
correct opcode to the control register. The watchdog will then count down towards 0 and
when 0 is reached the complete microcontroller will be reset . To avoid the reset, the
software must load new values into the watchdog register sufficiently often.
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8-bit CPU
register
REGX_CTRL
8-bit CPU
register
REGX_MSB
8-bit CPU
register
REGX_LSB
16-BIT BUS
Load
16-BIT
DOWN
COUNTER
Zero
Load
16-BIT
REGISTER
Load
16-BIT
DOWN
COUNTER
Zero
WAKEUP INT
TICK
WATCHDOG_RESET
Figure 8-18-2 : RTC and watchdog block diagram
RTC and Watchdog are controlled by SFRs 0xAB, 0xAC and 0xAD. These 3 registers
REGX_MSB, REGX_LSB and REGX_CTRL are used to interface the blocks running on
the slow LP_OSC clock. The 16-bit register {REGX_MSB, REGX_LSB} can be written
or read as two bytes from the CPU. Typical sequences are:
Write: Wait until not busy.
Write REGX_MSB, Write REGX_LSB, Write REGX_CTRL
Read: Wait until not busy.
Write REGX_CTRL, Wait until not busy.
Read REGX_MSB, Read REGX_LSB
Note : please also wait until not busy before accessing SFR 0xB6 CK_CTRL (page 66)
Addr
SFR
(hex)
AB
R/W #
b
i
t
R/W 8
AC
R/W
8
Init
(hex)
0
0
Name
Function
REGX_
MSB
REGX_
LSB
Most significant part of 16 bit register for
interface to Watchdog and RTC
Least significant part of 16 bit register for
interface to Watchdog and RTC
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AD
R/W
5
0
REGX_
CTRL
Control for 16 bit register for interface to
Watchdog and RTC. Bit 4 is only available on
read and is used to flag the interface unit as
busy.
Bits 3:0 is read/write with the encoding:
0 000: Read from WD register (16 bit)
1 000: Write to WD register (16 bit)
0 010: Read from RTC latch register (16 bit)
1 010: Write to RTC latch register (16 bit)
0 011: Read from RTC counter reg. (16 bit)
1 011: Disable RTC counter (no data)
Table 8-2 : RTC and Watchdog SFR-registers
8.4 Reset
nRF24E1 can be reset either by the on-chip power-on reset circuitry or by the on-chip
watchdog counter.
8.4.1 Power-on Reset
The power-on reset circuitry keeps the chip in power-on-reset state until the supply voltage
reaches VDDmin. At this point the internal voltage generators and oscillators start up, the
SFRs are initialized to their reset values, as listed in Table 10-10, and thereafter the CPU
begins program execution at the standard reset vector address 0x0000. The startup time
from power-on reset is about 14 LP_OSC cycles, which in total may vary from 3 to 15ms
depending on processing, temperature and supply voltage.
8.4.2 Watchdog Reset
If the Watchdog reset signal goes active, nRF24E1 enters the same reset sequence as for
power-on reset, that is the internal voltage generators and oscillators start up, the SFRs are
initialized to their reset values, as listed in Table 10-10, and thereafter the CPU begins
program execution at the standard reset vector address 0x0000. (of the existing program,
there is no reboot) The startup time from watchdog reset is somewhat shorter, 12 LP_OSC
cycles, which in total may vary from 2.5 to 13ms depending on processing, temperature and
supply voltage.
8.4.3 Program reset address
The program reset address is controlled by the RSTREAS register, SFR 0xB1, see Table
8-3 This register shows which reset source that caused the last reset, and provides a choice
of two different program start addresses. The default value is power-on reset, which starts
the boot loader, while a watchdog reset does not reboot, but restarts at address 0 of the
already loaded program.
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Addr
SFR
(hex)
B1
R/W #bit
R/W
2
Init
(hex)
02
Name
Function
RSTREAS
bit 0: Reason for last reset
0: POR
1: Any other reset source
Clear this bit in software to force a
reboot after jump to zero (boot loader
will load code RAM if this bit is 0)
bit 1: Use IROM for reset vector
0: Reset vectors to 0x0000.
1: Reset vectors to 0x8000.
Table 8-3 Reset control registe - SFR 0xB1.
9
POWER SAVING MODES
nRF24E1 provides the two industry standard 8051 power saving modes: idle mode and
stop mode, but with only minor power saving; therefore also a non standard power-down
mode is provided, where both oscillator and internal power regulators are turned off to
achieve more power saving.
The bits that control entry into idle and stop modes are in the PCON register at SFR
address 0x87, listed in Table 9-1. The bits that control entry into power down mode are in
the CK_CTRL register at SFR address 0xB6, listed in Table 9-2
Bit
PCON.7
Function
SMOD – Serial Port baud-rate doubler enable. When SMOD = 1, the
baud rate for Serial Port is doubled.
PCON.6–4 Reserved.
PCON.3
GF1 – General purpose flag 1. Bit-addressable, general purpose flag for
software control.
PCON.2
GF0 – General purpose flag 0. Bit-addressable, general purpose flag for
software control.
PCON.1
STOP – Stop mode select. Setting the STOP bit places the nRF24E1 in
stop mode.
PCON.0
IDLE – Idle mode select. Setting the IDLE bit places the nRF24E1 in idle
mode.
Table 9-1 : PCON Register – SFR 0x87
9.1 Idle Mode
An instruction that sets the IDLE bit (PCON.0) causes the nRF24E1 to enter idle mode
when that instruction completes. In idle mode, CPU processing is suspended and internal
registers and memory maintain their current data. However, unlike the standard 8051, the
CPU clock is not disabled internally, thus not much power is saved.
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There are two ways to exit idle mode: activate any enabled interrupt or watchdog reset.
Activation of any enabled interrupt causes the hardware to clear the IDLE bit and terminate
idle mode. The CPU executes the ISR associated with the received interrupt. The RETI
instruction at the end of the of ISR returns the CPU to the instruction following the one that
put the nRF24E1 into idle mode. A watchdog reset causes the nRF24E1 to exit idle mode,
reset internal registers, execute its reset sequence and begin program execution at the
standard reset vector address 0x0000.
9.2 Stop Mode
An instruction that sets the STOP bit (PCON.1) causes the nRF24E1 to enter stop mode
when that instruction completes. Stop mode is identical to idle mode, except that the only
way to exit stop mode is by watchdog reset Since there is little power saving, stop mode is
not recommended, as it is more efficient to use power down mode.
9.3 Power down mode
An instruction that sets the STOP_CLOCK bit (SFR 0xB6 CK_CTRL.1) causes the
nRF24E1 to enter power down mode when that instruction completes. In power down
mode, CPU processing is suspended, while internal registers and memories maintain their
current data. The CPU will perform a controlled shutdown of clock and power regulators.
But the transceiver subsystem has to be disabled separately by setting RADIO.7=0 before
stopping the clock.
The system can only be restarted from a low level on pin INT0_N (P0.3) or INT1_N
(P0.4) if enabled (by P0_ALT), or an RTC wakeup interrupt or a Watchdog reset. This
will cause the hardware to clear the CK_CTRL.1 bit and terminate power down mode. If
there is an enabled interrupt associated with the wakeup event, the CPU executes the ISR
associated with that interrupt immediately after power and clocks are restored. The RETI
instruction at the end of the of ISR returns the CPU to the instruction following the one that
put the nRF24E1 into power down mode. A watchdog reset causes the nRF24E1 to exit
power down mode, reset internal registers, execute its reset sequence and begin program
execution at the standard reset vector address 0x0000.
Note : Before accessing the CK_CTRL register, make sure that the busy bit of
RTC/Watchdog SFR 0xAD, bit 4 (page 64) is not set
Bit
CK_CTRL .0
CK_CTRL .1
Function
Not used
STOP_CLOCK. Setting the STOP_CLOCK bit
places the nRF24E1 in power down mode.
Table 9-2 : CK_CTRL register - SFR 0xB6
9.3.1
Clarification about wakeup and interrupt from external events
1: Wakeup and interrupt on pins P0.4 and P0.3 are intended to be parallel exclusive functions.
2: Interrupt circuitry is not active during power down and wakeup not active during power up.
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3: however when the nRF24E1 is started by one of these pins, the event will be captured in the
interrupt circuitry also and an interrupt MAY be delivered if enabled. A level interrupt will always
be delivered (even if pin has returned high). A falling edge interrupt may be delivered.
9.3.2 Startup time from Power down mode.
Startup time consists of a number of LP_OSC cycles + a number of XTAL clock cycles.
fLP_OSC may vary from 1 to 5.5kHz over voltage and temperature, but can be measured as
described on page 61. fXTAL depends on the selected crystal, as described on page 108.
Because frequency fXTAL is much higher, startup time is dominated by fLP_OSC.
Startup times are summarized in the table below :
Reason of startup
Startup time
in fLP_OSC cycles
Power-on reset
Watchdog reset
External interrupt
14-15
12
3-4
Startup time
in fXTAL cycles
24
24
max 52,
see ch. 7.6
RTC interrupt
3
max 52
see ch. 7.6
Table 9-3 : Startup times from Power down mode
Example of total
startup time
if fLP_OSC =3kHz
if fXTAL =16MHz
4.8 ms
4.0 ms
1.2 ms
1.0 ms
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10 MICROCONTROLLER
The embedded microcontroller is the DW8051 MacroCell from Synopsys which is similar
to the Dallas DS80C320 in terms of hardware features and instruction-cycle timing.
10.1 Memory Organization
FFFFh
81FFh
Boot loader
8000h
IRAM
SFR
FFh
Upper
128
bytes.
FFh
Accessible by
indirect
addressing only.
Accessible by
direct addressing
only.
80h
7Fh
0FFFh
Program/data memory.
Accessible with movc and
movx.
Lower
128
bytes.
0000h
80h
Accessible by
direct and indirect
addressing.
Special
Function
Registers
00h
Program memory/Data
Memory (ERAM)
Internal Data Memory
Figure 10-1 : Memory Map and Organization
10.1.1 Program Memory/Data Memory
The nRF24E1 has 4KB of program memory available for user programs located at the
bottom of the address space as shown in Figure 10-1. This memory also function as a
random access memory and can be accessed with the movx and movc instructions.
After power on reset the boot loader loads the user program from the external serial
EEPROM and stores it from address 0 in this memory.
10.1.1.1 Memory paging
A Special function register, MPAGE, at SFR address 0x92 provides memory paging
function. During MOVX A, @Ri and MOVX @Ri, A instructions, the contents of the
MPAGE register are placed on the upper eight address bits of memory address.
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10.1.2 Internal Data Memory
The Internal Data Memory, illustrated in Figure 10-1, consists of:
•
•
•
128 bytes of registers and scratchpad memory accessible through direct or indirect
addressing (addresses 0x00–0x7F).
128 bytes of scratchpad memory accessible through indirect addressing (0x80–
0xFF).
128 special function registers (SFRs) accessible through direct addressing.
The lower 32 bytes form four banks of eight registers (R0–R7). Two bits on the program
status word (PSW) select which bank is in use. The next sixteen bytes form a block of bitaddressable memory space at bit addresses 0x00–0x7F. All of the bytes in the lower 128
bytes are accessible through direct or indirect addressing. The SFRs and the upper 128
bytes of RAM share the same address range (0x80-0xFF). However, the actual address
space is separate and is differentiated by the type of addressing. Direct addressing accesses
the SFRs, while indirect addressing accesses the upper 128 bytes of RAM. Most SFRs are
reserved for specific functions, as described in 10.6Special Function Registers on page 78.
SFR addresses ending in 0h or 8h are bit-addressable.
10.2 Program format in external EEPROM
The table below shows the layout of the first few bytes of the EEPROM image.
7
6
5
4
3
2
1
0
Version
Reserved
SPEED
XO_FREQ
(now 00)
(now 00)
1:
Offset to start of user program (N)
2:
Number of 256 byte blocks in user program (includes block 0 that is not full)
…
Optional User data, not interpreted by boot loader
…
…
N:
First byte of user program, goes into ERAM at 0x0000
N+1: Second byte of user program, goes into ERAM at 0x0001
…
Table 10-1 : EEPROM layout
0:
The contents of the 4 lowest bits in the first byte is used by the boot loader to set the correct
SPI frequency. These fields are encoded as shown below:
SPEED (bit 3): EEPROM max speed
0 = 1MHz
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1 = 0.5MHz
XO_FREQ (bits 2,1 and 0): Crystal oscillator frequency
000 = 4MHz,
001 = 8MHz,
010 = 12MHz,
011 = 16MHz,
100 = 20MHz
The program eeprep can be used to add this header to a program file.
Command format: eeprep [options]
is the output file of an assembler or compiler
is a file suitable for programming the EEPROM (above format with no user data).
Both files are “Intelhex” format.
The options available for eeprep are:
-c n
Set crystal frequency in MHz. Valid numbers are 4, 8, 12, 16 (default) and
20
-i
Ignore checksums
-p n Set program memory size (default 4096 bytes)
-s
Select slow EEPROM clock (500KHz)
10.3 Instruction Set
All nRF24E1 instructions are binary-code–compatible and perform the same functions that
they do in the industry standard 8051. The effects of these instructions on bits, flags, and
other status functions is identical to the industry-standard 8051. However, the timing of the
instructions is different, both in terms of number of clock cycles per instruction cycle and
timing within the instruction cycle.
The instruction set is fully compatible to the instruction set of nRF24E2.
Table 10-3 to Table 10-8 lists the nRF24E1 instruction set and the number of instruction
cycles required to complete each instruction.
Symbol
Function
A
Accumulator
Rn
Register R0–R7
direct
Internal register address
@Ri
Internal register pointed to by R0 or R1 (except MOVX)
rel
Two’s complement offset byte
bit
Direct bit address
#data
8-bit constant
#data 16
16-bit constant
addr 16
16-bit destination address
addr 11
11-bit destination address
Table 10-2 : Legend for Instruction Set Table
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Table 10-3 to Table 10-8 define the symbols and mnemonics used in Table 10-2.
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Mnemonic
Arithmetic Instructions
Description
Byte
ADD A, Rn
ADD A, direct
ADD A, @Ri
ADD A, #data
ADDC A, Rn
ADDC A, direct
ADDC A, @Ri
Instr.
Cycles
1
2
1
2
1
2
1
Add register to A
1
Add direct byte to A
2
Add data memory to A
1
Add immediate to A
2
Add register to A with carry
1
Add direct byte to A with carry 2
Add data memory to A with
1
carry
ADDC A, #data Add immediate to A with carry 2
2
SUBB A, Rn
Subtract register from A with
1
1
borrow
SUBB A, direct Subtract direct byte from A
2
2
with borrow
SUBB A, @Ri
Subtract data memory from A
1
1
with borrow
SUBB A, #data Subtract immediate from A with 2
2
borrow
INC A
Increment A
1
1
INC Rn
Increment register
1
1
INC direct
Increment direct byte
2
2
INC @Ri
Increment data memory
1
1
DEC A
Decrement A
1
1
DEC Rn
Decrement register
1
1
DEC direct
Decrement direct byte
2
2
DEC @Ri
Decrement data memory
1
1
INC DPTR
Increment data pointer
1
3
MUL AB
Multiply A by B
1
5
DIV AB
Divide A by B
1
5
DA A
Decimal adjust A
1
1
All mnemonics are copyright © Intel Corporation 1980.
Hex
Code
28–2F
25
26–27
24
38–3F
35
36–37
34
98–9F
95
96–97
94
04
08–0F
05
06–07
14
18–1F
15
16–17
A3
A4
84
D4
Table 10-3 : nRF24E1 Instruction Set, Arithmetic Instructions.
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Mnemonic
Logical Instructions
Description
Byte
ANL A, Rn
ANL A, direct
ANL A, @Ri
ANL A, #data
ANL direct, A
ANL direct,
#data
ORL A, Rn
ORL A, direct
ORL A, @Ri
ORL A, #data
ORL direct, A
ORL direct,
#data
XRL A, Rn
XRL A, direct
XRL A, @Ri
Instr.
Cycles
1
2
1
2
2
3
AND register to A
1
AND direct byte to A
2
AND data memory to A
1
AND immediate to A
2
AND A to direct byte
2
AND immediate data to direct
3
byte
OR register to A
1
1
OR direct byte to A
2
2
OR data memory to A
1
1
OR immediate to A
2
2
OR A to direct byte
2
2
OR immediate data to direct
3
3
byte
Exclusive-OR register to A
1
1
Exclusive-OR direct byte to A 2
2
Exclusive-OR data memory to
1
1
A
XRL A, #data
Exclusive-OR immediate to A
2
2
XRL direct, A
Exclusive-OR A to direct byte
2
2
XRL direct,
Exclusive-OR immediate to
3
3
#data
direct byte
CLR A
Clear A
1
1
CPL A
Complement A
1
1
SWAP A
Swap nibbles of A
1
1
RL A
Rotate A left
1
1
RLC A
Rotate A left through carry
1
1
RR A
Rotate A right
1
1
RRC A
Rotate A right through carry
1
1
All mnemonics are copyright © Intel Corporation 1980.
Hex
Code
58–5F
55
56–57
54
52
53
48–4F
45
46–47
44
42
43
68–6F
65
66–67
64
62
63
E4
F4
C4
23
33
03
13
Table 10-4 : nRF24E1 Instruction Set, Logical Instructions.
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Mnemonic
Boolean Instructions
Description
Byte
Instr.
Cycles
CLR C
Clear carry
1
1
CLR bit
Clear direct bit
2
2
SETB C
Set carry
1
1
SETB bit
Set direct bit
2
2
CPL C
Complement carry
1
1
CPL bit
Complement direct bit
2
2
ANL C, bit
AND direct bit to carry
2
2
ANL C, /bit
AND direct bit inverse to carry 2
2
ORL C, bit
OR direct bit to carry
2
2
ORL C, /bit
OR direct bit inverse to carry
2
2
MOV C, bit
Move direct bit to carry
2
2
MOV bit, C
Move carry to direct bit
2
2
All mnemonics are copyright © Intel Corporation 1980.
Hex
Code
C3
C2
D3
D2
B3
B2
82
B0
72
A0
A2
92
Table 10-5 : nRF24E1 Instruction Set, Boolean Instructions.
Mnemonic
MOV A, Rn
MOV A, direct
MOV A, @Ri
MOV A, #data
MOV Rn, A
MOV Rn, direct
MOV Rn, #data
MOV direct, A
MOV direct, Rn
MOV direct,
direct
MOV direct,
@Ri
MOV direct,
#data
MOV @Ri, A
MOV @Ri,
Data Transfer Instructions
Description
Byte
Move register to A
Move direct byte to A
Move data memory to A
Move immediate to A
Move A to register
Move direct byte to register
Move immediate to register
Move A to direct byte
Move register to direct byte
Move direct byte to direct byte
1
2
1
2
1
2
2
2
2
3
Instr.
Cycles
1
2
1
2
1
2
2
2
2
3
Hex
Code
E8–EF
E5
E6–E7
74
F8–FF
A8–AF
78–7F
F5
88–8F
85
Move data memory to direct
byte
Move immediate to direct byte
2
2
86–87
3
3
75
Move A to data memory
Move direct byte to data
1
2
1
2
F6–F7
A6–A7
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direct
MOV @Ri,
#data
MOV DPTR,
#data
MOVC A,
@A+DPTR
MOVC A,
@A+PC
MOVX A, @Ri
MOVX A,
@DPTR
MOVX @Ri, A
MOVX
@DPTR, A
PUSH direct
POP direct
XCH A, Rn
XCH A, direct
XCH A, @Ri
XCHD A, @Ri
memory
Move immediate to data
2
memory
Move immediate to data pointer 3
2
76–77
3
90
Move code byte relative DPTR
to A
Move code byte relative PC to
A
Move external data (A8) to A
Move external data (A16) to A
1
3
93
1
3
83
1
1
2–9*
2–9*
E2–E3
E0
Move A to external data (A8)
Move A to external data (A16)
1
1
2–9*
2–9*
F2–F3
F0
Push direct byte onto stack
2
2
Pop direct byte from stack
2
2
Exchange A and register
1
1
Exchange A and direct byte
2
2
Exchange A and data memory
1
1
Exchange A and data memory
1
1
nibble
All mnemonics are copyright © Intel Corporation 1980.
C0
D0
C8–CF
C5
C6–C7
D6–D7
Table 10-6 : nRF24E1 Instruction Set, Data Transfer Instructions.
* Number of cycles is 2 + CKCON.2-0. (CKCON.2-0 is the integer value of the 3LSB of
SFR 0x8E CKCON). Default is 3 cycles.
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Mnemonic
ACALL addr 11
LCALL addr 16
RET
RETI
AJMP addr 11
LJMP addr 16
SJMP rel
JC rel
JNC rel
JB bit, rel
JNB bit, rel
JBC bit, rel
JMP
@A+DPTR
JZ rel
JNZ rel
CJNE A, direct,
rel
CJNE A, #d, rel
Branching Instructions
Description
Byte
Absolute call to subroutine
Long call to subroutine
Return from subroutine
Return from interrupt
Absolute jump unconditional
Long jump unconditional
Short jump (relative address)
Jump on carry = 1
Jump on carry = 0
Jump on direct bit = 1
Jump on direct bit = 0
Jump on direct bit = 1 and clear
Jump indirect relative DPTR
2
3
1
1
2
3
2
2
2
3
3
3
1
Instr.
Cycles
3
4
4
4
3
4
3
3
3
4
4
4
3
Jump on accumulator = 0
Jump on accumulator /= 0
Compare A, direct JNE relative
2
2
3
3
3
4
Compare A, immediate JNE
3
4
relative
CJNE Rn, #d, rel Compare reg, immediate JNE
3
4
relative
CJNE @Ri, #d, Compare ind, immediate JNE
3
4
rel
relative
DJNZ Rn, rel
Decrement register, JNZ
2
3
relative
DJNZ direct, rel Decrement direct byte, JNZ
3
4
relative
All mnemonics are copyright © Intel Corporation 1980.
Hex
Code
11–F1
12
22
32
01–E1
02
80
40
50
20
30
10
73
60
70
B5
B4
B8–BF
B6–B7
D8–DF
D5
Table 10-7 : nRF24E1 Instruction Set, Branching Instructions.
Mnemonic
Miscellaneous Instructions
Description
Byte
NOP
No operation
1
Instr.
Cycles
1
Hex
Code
00
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There is an additional reserved opcode (A5) that performs the same function as
NOP.
All mnemonics are copyright © Intel Corporation 1980.
Table 10-8 : nRF24E1 Instruction Set, Miscellaneous Instructions.
10.4 Instruction Timing
Instruction cycles in the nRF24E1 are four clock cycles in length, as opposed to twelve
clock cycles per instruction cycle in the standard 8051. This translates to a 3X improvement
in execution time for most instructions. However, some instructions require a different
number of instruction cycles on the nRF24E1 than they do on the standard 8051. In the
standard 8051, all instructions except for MUL and DIV take one or two instruction cycles
to complete. In the nRF24E1 architecture, instructions can take between one and five
instruction cycles to complete. For example, in the standard 8051, the instructions MOVX
A, @DPTR and MOV direct, direct each take two instruction cycles (twenty-four clock
cycles) to execute. In the nRF24E1 architecture, MOVX A, @DPTR takes two instruction
cycles (eight clock cycles) and MOV direct, direct takes three instruction cycles (twelve
clock cycles). Both instructions execute faster on the nRF24E1 than they do on the standard
8051, but require different numbers of clock cycles.
For timing of real-time events, use the numbers of instruction cycles from Table 10-3 to
Table 10-8 to calculate the timing of software loops. The bytes column of these table
indicates the number of memory accesses (bytes) needed to execute the instruction. In most
cases, the number of bytes is equal to the number of instruction cycles required to complete
the instruction. However, as indicated in Table 10-3, there are some instructions (for
example, DIV and MUL) that require a greater number of instruction cycles than memory
accesses.By default, the nRF24E1 timer/counters run at twelve clock cycles per increment
so that timer-based events have the same timing as with the standard 8051. The timers can
be configured to run at four clock cycles per increment to take advantage of the higher
speed of the nRF24E1.
10.5 Dual Data Pointers
The nRF24E1 employs dual data pointers to accelerate data memory block moves. The
standard 8051 data pointer (DPTR) is a 16-bit value used to address external data RAM or
peripherals. The nRF24E1 maintains the standard data pointer as DPTR0 at SFR locations
0x82 and 0x83. It is not necessary to modify code to use DPTR0. The nRF24E1 adds a
second data pointer (DPTR1) at SFR locations 0x84 and 0x85. The SEL bit in the DPTR
Select register, DPS (SFR 0x86), selects the active pointer. When SEL = 0, instructions
that use the DPTR will use DPL and DPH. When SEL=1, instructions that use the DPTR
will use DPL1 and DPH1. SEL is the bit 0 of SFR location 0x86. No other bits of SFR
location 0x86 are used. All DPTR-related instructions use the currently selected data
pointer. To switch the active pointer, toggle the SEL bit. The fastest way to do so is to use
the increment instruction (INC DPS). This requires only one instruction to switch from a
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source address to a destination address, saving application code from having to save source
and destination addresses when doing a block move.
Using dual data pointers provides significantly increased efficiency when moving large blocks
of data.
The SFR locations related to the dual data pointers are:
- 0x82 DPL DPTR0 low byte
- 0x83 DPH DPTR0 high byte
- 0x84 DPL1 DPTR1 low byte
- 0x85 DPH1 DPTR1 high byte
- 0x86 DPS DPTR Select (LSB)
10.6 Special Function Registers
The Special Function Registers (SFRs) control several of the features of the nRF24E1.
Most of the nRF24E1 SFRs are identical to the standard 8051 SFRs. However, there are
additional SFRs that control features that are not available in the standard 8051. Table
10-9 lists the nRF24E1 SFRs and indicates which SFRs are not included in the standard
8051 SFR space. When writing software for the nRF24E1, use equate statements to define
the SFRs that are specific to the nRF24E1 and custom peripherals. In Table 10-9, SFR bit
positions that contain a 0 or a 1 cannot be written to and, when read, always return the
value shown (0 or 1). SFR bit positions that contain “–” are available but not used. Table
10-10 shows the value of each SFR, after power-on reset or a watchdog reset, together
with a pointer to a detailled description of each register. Please note that any unused address
in the SFR address space is reserved and should not be written to.
Notes to Table 10-9 on next page :
(1) Not part of standard 8051 architecture.
(2) Registers unique to nRF24E1
(3) P0 and P1 differ from standard 8051
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PRODUCT SPECIFICATION
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Addr
0x80
0x81
0x82
0x83
0x84
0x85
0x86
0x87
0x88
0x89
0x8A
0x8B
0x8C
0x8D
0x8E
0x8F
0x90
0x91
0x92
0x94
0x95
0x96
0x97
0x98
0x99
0xA0
0xA1
0xA2
0xA3
0xA4
0xA8
0xA9
0xAA
0xAB
0xAC
0xAD
0xB1
0xB2
0xB3
0xB4
0xB5
0xB6
Register
P0(3)
SP
DPL
DPH
DPL1(1)
DPH1(1)
DPS(1)
PCON
TCON
TMOD
TL0
TL1
TH0
TH1
CKCON(1)
SPC_FNC(1)
P1(3)
EXIF(1)
MPAGE(1)
P0_DIR(2)
P0_ALT(2)
P1_DIR(2)
P1_ALT(2)
SCON
SBUF
RADIO(2)
ADCCON(2)
ADCDATAH(2)
ADCDATAL(2)
ADCSTATIC(2)
IE
PWMCON(2)
PWMDUTY(2)
REGX_MSB(2)
REGX_LSB(2)
REGX_CTRL(2)
RSTREAS(2)
SPI_DATA(2)
SPI_CTRL(2)
SPICLK(2)
TICK_DV(2)
CK_CTRL(2)
Bit 7
Bit 6
Bit 5
Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Port 0
Stack pointer
Data pointer 0, low byte
Data pointer 0, high byte
Data pointer 1, low byte
Data pointer 1, high byte
0
0
0
0
0
0
0
SEL
SMOD
1
1
GF1
GF0
STOP
IDLE
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
GATE
C/T
M1
M0
GATE
C/T
M1
M0
Timer/counter 0 value, low byte
Timer/counter 1 value, low byte
Timer/counter 0 value, high byte
Timer/counter 1 value, high byte
T2M
T1M
T0M
MD2
MD1
MD0
0
0
0
0
0
0
0
WRS
Port 1 bit 2:0
IE5
IE4
IE3
IE2
1
0
0
0
program/data memory page address
Direction of Port 0
Alternate functions of Port 0
Direction of Port 1
alt.funct.of Port 1
SM0
SM1
SM2
REN
TB8
RB8
TI
RI
Serial port data buffer
PWR_UP DR2/CE CLK2
DOUT2 CS
DR1
CLK1
DATA
CSTRTN ADCRUN NPD
EXTREF
ADCSEL
High bits of ADC result
Low bits of ADC result
ADCUF ADCOF ADCRNG
DIFFM SLEEP CLK8
ADCBIAS
ADCRES
EA
0
ET2
ES
ET1
EX1
ET0
EX0
PWM_LENGTH
PWM_PRESCALE
PWM_DUTY_CYCLE
High byte of Watchdog/RTC register
Low byte of Watchdog/RTC register
Control of REGX_MSB and REGX_LSB
RFLR
SPI_DATA input/output bits
SPI_CTRL
SPICLK
TICK_DV
CK_CTRL
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0xB8
0xC8
0xCA
0xCB
0xCC
0xCD
0xD0
0xD8
0xE0
0xE8
0xF0
0xF8
0xFE
0xFF
IP
T2CON
RCAP2L
RCAP2H
TL2
TH2
PSW
EICON(1)
ACC
EIE(1)
B
EIP(1)
HWREV
-----
1
TF2
CY
-
1
1
0
PT2
PS
PT1
PX1
PT0
PX0
CP/RL2
EXF2
RCLK
TCLK
EXEN2 TR2
C/T2
Timer/counter 2 capture or reload, low byte
Timer/counter 2 capture or reload, high byte
Timer/counter 2 value, low byte
Timer/counter 2 value, high byte
AC
F0
RS1
RS0
OV
F1
P
1
0
0
WDTI
0
0
0
Accumulator register
1
1
EWDI
EX5
EX4
EX3
EX2
B-register
1
1
PWDI
PX5
PX4
PX3
PX2
Device hardware revision number
Reserved, do not use
Table 10-9 : Special Function Registers summary
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Register
ACC
ADCCON
ADCDATAH
ADCDATAL
ADCSTATIC
B
CK_CTRL
CKCON
DPH
DPH1
DPL
DPL1
DPS
EICON
EIE
EIP
EXIF
HWREV
IE
IP
MPAGE
P0
P0_ALT
P0_DIR
P1
P1_ALT
P1_DIR
PCON
PSW
PWMCON
PWMDUTY
RADIO
RCAP2H
RCAP2L
REGX_CTRL
REGX_LSB
REGX_MSB
RSTREAS
SBUF
SCON
SP
SPC_FNC
SPI_CTRL
SPI_DATA
SPICLK
T2CON
TCON
TH0
TH1
Addr
0xE0
0xA1
0xA2
0xA3
0xA4
0xF0
0xB6
0x8E
0x83
0x85
0x82
0x84
0x86
0xD8
0xE8
0xF8
0x91
0xFE
0xA8
0xB8
0x92
0x80
0x95
0x94
0x90
0x97
0x96
0x87
0xD0
0xA9
0xAA
0xA0
0xCB
0xCA
0xAD
0xAC
0xAB
0xB1
0x99
0x98
0x81
0x8F
0xB3
0xB2
0xB4
0xC8
0x88
0x8C
0x8D
Reset value
0x00
0x80
read only
read only
0x0A
0x00
0x00
0x01
0x00
0x00
0x00
0x00
0x00
0x40
0xE0
0xE0
0x08
0x00,read only
0x00
0x80
0x00
0xFF
0x00
0xFF
0xFF
0x00
0xFF
0x30
0x00
0x00
0x00
0x80
0x00
0x00
0x00
0x00
0x00
0x02
0x00
0x00
0x07
0x00
0x00
0x00
0x00
0x00
0x00
0x00
0x00
Description
Accumulator register
Table 5-1, page 49
Table 5-3, page 49
Table 5-3, page 49
Table 5-2, page 49
B-register
Table 9-2, page 66
Table 10-15, page 88
ch.10.5, page 77
ch.10.5, page 77
ch.10.5, page 77
ch.10.5, page 77
ch.10.5, page 77
Table 7-5, page 57
Table 7-6, page 57
Table 7-7, page 58
Table 7-4, page 57
hardware revision no
Table 7-2, page 56
Table 7-3, page 56
ch.10.1.1.1, page 68
Table 3-3, page 15
Table 3-3, page 15
Table 3-3, page 15
Table 1-1, page 17
Table 3-5, page 17
Table 3-5, page 17
Table 9-1, page 65
Table 10-11, page 82
Table 6-1, page 54
Table 6-1, page 54
Table 4-2, page 21
ch.10.8.3.3, page 90
ch.10.8.3.3, page 90
Table 8-2, page 64
Table 8-2, page 64
Table 8-2, page 64
Table 8-3, page 65
ch.10.9, page 92
Table 10-19, page 93
Stack pointer
do not use
Table 3-6, page 18
Table 3-6, page 18
Table 3-6, page 18
Table 10-16, page 90
Table 10-14, page 85
ch.10.8, page 84
ch.10.8, page 84
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TH2
TICK_DV
TL0
TL1
TL2
TMOD
0xCD
0xB5
0x8A
0x8B
0xCC
0x89
0x00
0x1D
0x00
0x00
0x00
0x00
ch.10.8, page 84
Table 8-1, page 61
ch.10.8, page 84
ch.10.8, page 84
ch.10.8, page 84
Table 10-13, page 85
Table 10-10 : Special Function Register reset values and description, alphabetically.
Table 10-11 lists the functions of the bits in the PSW register.
Bit
PSW.7
Function
CY - Carry flag. Set to 1 when last arithmetic operation resulted in a carry (during addition)
or borrow (during subtraction); otherwise cleared to 0 by all arithmetic operations.
AC - Auxiliary carry flag. Set to 1 when last arithmetic operation resulted in a carry into
(during addition) or borrow from (during subtraction) the high-order nibble; otherwise
cleared to 0 by all arithmetic operations.
F0 - User flag 0. Bit-addressable, general purpose flag for software control.
RS1 - Register bank select bit 1. Used with RS0 to select a register blank in internal RAM.
RS0 - Register bank select bit 0, decoded as:
RS1 RS0 Bank selected
0 0 Register bank 0, addresses 0x00-0x07
0 1 Register bank 1, addresses 0x08-0x0F
1 0 Register bank 2, addresses 0x10-0x17
1 1 Register bank 3, addresses 0x18-0x1F
PSW.6
PSW.5
PSW.4
PSW.3
PSW.2
OV - Overflow flag. Set to 1 when last arithmetic operation resulted in a carry (addition),
borrow (subtraction), or overflow (multiply or divide); otherwise cleared to 0 by all
arithmetic operations.
F1 - User flag 1. Bit-addressable, general purpose flag for software control.
P - Parity flag. Set to 1 when modulo-2 sum of 8 bits in accumulator is 1 (odd parity);
cleared to 0 on even parity.
PSW.1
PSW.0
Table 10-11 : PSW Register – SFR 0xD0
10.7 SFR registers unique to nRF24E1
The table below lists the SFR registers that are unique to nRF24E1 (not part of standard
8051 register map) The registers P0, P1 and RADIO use the addresses for the ports P0,
P1 and P2 in a standard 8051. Whereas the functionality of these ports is similar to that of
the corresponding ports in standard 8051, it is not identical.
Addr
SFR
80∗
∗
R/W #bit
R/W
8
Init
hex
FF
Name
Function
P0
Port 0, pins DIO9 to DIO2
This bit addressable register differs in usage from “standard 8051”
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Addr
SFR
90*
94
95
96
97
A0*
R/W #bit
R/W
R/W
R/W
R/W
R/W
R/W
8(3)
8
8
8(3)
8(3)
8
Init
hex
FF
FF
00
FF
00
80
Name
Function
P15
P0_DIR
P0_ALT
P1_DIR
P1_ALT
RADIO
Port 1, pins DIN0, DI1, DI0
Direction of each GPIO bit of port 0
Select alternate functions for each pin of port 0
Direction for each GPIO bit of port 1
Select alternate functions for each pin of port 1
General purpose IO for interface to
2401 radio, for details see ch. 4 nRF2401
2.4GHz TRANSCEIVER SUBSYSTEM
ADC control register
High 8 bits of ADC result
Low bits of ADC result (if any) and status
Static configuration data for ADC:
PWM control register
PWM duty cycle
High part of 16 bit register for interface to
Watchdog and RTC
Low part of 16 bit register for interface to
Watchdog and RTC
Control of interface to Watchdog and RTC.
Reset status and control
SPI data input/output
00 -> SPI not used 01 -> connect to P1
10 or 11 -> connect to RADIO
Divider from CPU clock to SPI clock
TICK Divider.
Clock control
Test mode register.
This register must always be 0 in normal mode.
Another 3 test mode registers.
Initial values must not be changed.
A1
A2
A3
A4
A9
AA
AB
R/W
R
R
R/W
R/W
R/W
R/W
8
8
8
6
8
8
8
80
XX
XX
0A
0
0
0
ADCCON
ADCDATAH
ADCDATAL
ADCSTATIC
PWMCON
PWMDUTY
REGX_MSB
AC
R/W
8
0
REGX_LSB
AD
B1
B2
B3
R/W
R/W
R/W
R/W
5
2
8
2
0
02
0
0
REGX_CTRL
RSTREAS
SPI_DATA
SPI_CTRL
B4
B5
B6
B7
R/W
R/W
W
R
2
8
2
4
0
1D
0
0
SPICLK
TICK_DV
CK_CTRL
TEST_MODE
BC
RW
8
#
T1_1V2
BD
RW
8
#
T2_1V2
BE
RW
4
#
DEV_OFFSET
Table 10-12 : SFR registers unique to nRF24E1
5
Only 3 lower bits are meaningful in P1 and corresponding P1_DIR and P1_ALT
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10.8 Timers/Counters
The nRF24E1 includes three timer/counters (Timer 0, Timer 1 and Timer 2). Each
timer/counter can operate as either a timer with a clock rate based on the CPU clock , or as
an event counter clocked by the t0 pin (Timer 0), t1 pin (Timer 1), or the t2 pin (Timer 2).
These pins are alternate function bits of Port 0 and 1 as this : t0 is P0.5, t1 is P0.6 and t2 is
P1.0, for details please see ch. 3 I/O PORTS.
Each timer/counter consists of a 16-bit register that is accessible to software as three SFRs:
(Table 10-9 : Special Function Registers)
- Timer 0 - TL0 and TH0
- Timer 1 - TL1 and TH1
- Timer 2 - TL2 and TH2
10.8.1 Timers 0 and 1
Timers 0 and 1 each operate in four modes, as controlled through the TMOD SFR
(Table 10-13) and the TCON SFR (Table 10-14). The four modes are:
- 13-bit timer/counter (mode 0)
- 16-bit timer/counter (mode 1)
- 8-bit counter with auto-reload (mode 2)
- Two 8-bit counters (mode 3, Timer 0 only)
Bit
TMOD.7
TMOD.6
TMOD.5
TMOD.4
TMOD.3
TMOD.2
TMOD.1
TMOD.0
Function
GATE - Timer 1 gate control. When GATE = 1, Timer 1 will clock only when external interrupt
INT1_N = 1 and TR1 (TCON.6) = 1. When GATE = 0, Timer 1 will clock only when TR1 = 1,
regardless of the state of INT1_N.
C/T - Counter/Timer select. When C/T = 0, Timer 1 is clocked by CPU_clk/4 or CPU_clk/12,
depending on the state of T1M (CKCON.4). When C/T = 1, Timer 1 is clocked by the t1 pin.
M1 - Timer 1 mode select bit 1.
M0 - Timer 1 mode select bit 0, decoded as:
M1 M0 Mode
00 Mode 0 : 13-bit counter
01 Mode 1 : 16-bit counter
10 Mode 2 : 8-bit counter with auto-reload
11 Mode 3 : Two 8-bit counters
GATE - Timer 0 gate control. When GATE = 1, Timer 0 will clock only when external interrupt
INT0_N = 1 and TR0 (TCON.4) = 1. When GATE = 0, Timer 0 will clock only when TR0 = 1,
regardless of the state of INT0_N.
C/T - Counter/Timer select. When C/T = 0, Timer 0 is clocked by CPU_clk/4 or CPU_clk/12,
depending on the state of T0M (CKCON.3). When C/T = 1, Timer 0 is clocked by the t0 pin.
M1 - Timer 0 mode select bit 1.
M0 - Timer 0 mode select bit 0, decoded as:
M1 M0 Mode
00 Mode 0 : 13-bit counter
01 Mode 1 : 16-bit counter
10 Mode 2 : 8-bit counter with auto-reload
11 Mode 3 : Two 8-bit counters
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Table 10-13 : TMOD Register – SFR 0x89
Bit
TCON.7
TCON.6
TCON.5
TCON.4
TCON.3
TCON.2
TCON.1
TCON.0
Function
TF1 - Timer 1 overflow flag. Set to 1 when the Timer 1 count overflows and cleared when
the CPU vectors to the interrupt service routine.
TR1 - Timer 1 run control. Set to 1 to enable counting on Timer 1.
TF0 - Timer 0 overflow flag. Set to 1 when the Timer 0 count overflows and cleared when
the CPU vectors to the interrupt service routine.
TR0 - Timer 0 run control. Set to 1 to enable counting on Timer 0.
IE1 - Interrupt 1 edge detect. If external interrupt 1 is configured to be edge-sensitive (IT1 =
1), IE1 is set by hardware when a negative edge is detected on the INT1_N external
interrupt pin and is automatically cleared when the CPU vectors to the corresponding
interrupt service routine. In edge-sensitive mode, IE1 can also be cleared by software.
If external interrupt 1 is configured to be level-sensitive (IT1 = 0), IE1 is set when the
INT1_N pin is low and cleared when the INT1_N pin is high. In level-sensitive mode,
software cannot write to IE1.
IT1 - Interrupt 1 type select. When IT1 = 1, the nRF24E1 detects external interrupt pin
INT1_N on the falling edge (edge-sensitive). When IT1 = 0, the nRF24E1 detects INT1_N
as a low level (level-sensitive).
IE0 - Interrupt 0 edge detect. If external interrupt 0 is configured to be edge-sensitive (IT0 =
1), IE0 is set by hardware when a negative edge is detected on the INT0_N external
interrupt pin and is automatically cleared when the CPU vectors to the corresponding
interrupt service routine. In edge-sensitive mode, IE0 can also be cleared by software.
If external interrupt 0 is configured to be level-sensitive (IT0 = 0), IE0 is set when the
INT0_N pin is low and cleared when the INT0_N pin is high. In level-sensitive mode,
software cannot write to IE0.
IT0 - Interrupt 0 type select. When IT0 = 1, the nRF24E1 detects external interrupt INT0_N
on the falling edge (edge-sensitive). When IT0 = 0, the nRF24E1 detects INT0_N as a low
level (level-sensitive).
Table 10-14 : TCON Register – SFR 0x88
10.8.1.1 Mode 0
Mode 0 operation, illustrated in Figure 10-2 : Timer 0/1 – Modes 0 and 1, is the same for
Timer 0 and Timer 1. In mode 0, the timer is configured as a 13-bit counter that uses bits 0–
4 of TL0 (or TL1) and all eight bits of TH0 (or TH1). The timer enable bit (TR0/TR1) in the
TCON SFR starts the timer. The C/T bit selects the timer/counter clock source, CPU_clk
or t0/t1. The timer counts transitions from the selected source as long as the GATE bit is 0,
or the GATE bit is 1 and the corresponding interrupt pin (INT0_N or INT1_N) is
deasserted. INT0_N and INT1_N are alternate function bits of Port0, please seeTable 3-1
: Port functions. When the 13-bit count increments from 0x1FFF (all ones), the counter rolls
over to all zeros, the TF0 (or TF1) bit is set in the TCON SFR, and the t0_out (or t1_out)
pin goes high for one clock cycle. The upper three bits of TL0 (or TL1) are indeterminate in
mode 0 and must be masked when the software evaluates the register.
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10.8.1.2 Mode 1
Mode 1 operation is the same for Timer 0 and Timer 1. In mode 1, the timer is configured
as a 16-bit counter. As illustrated in Figure 10-2 : Timer 0/1 – Modes 0 and 1, all eight bits
of the LSB register (TL0 or TL1) are used. The counter rolls over to all zeros when the
count increments from 0xFFFF. Otherwise, mode 1 operation is the same as mode 0.
Figure 10-2 : Timer 0/1 – Modes 0 and 1
10.8.1.3 Mode 2
Mode 2 operation is the same for Timer 0 and Timer 1. In mode 2, the timer is configured
as an 8-bit counter, with automatic reload of the start value. The LSB register (TL0 or TL1)
is the counter, and the MSB register (TH0 or TH1) stores the reload value. As illustrated in
Figure 10-3 : Timer 0/1 – Mode 2, mode 2 counter control is the same as for mode 0 and
mode 1. However, in mode 2, when TLn increments from 0xFF, the value stored in THn is
reloaded into TLn.
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Figure 10-3 : Timer 0/1 – Mode 2
10.8.1.4 Mode 3
In mode 3, Timer 0 operates as two 8-bit counters, and Timer 1 stops counting and holds
its value. As shown in Figure 10-4 : Timer 0 – Mode 3, TL0 is configured as an 8-bit
counter controlled by the normal Timer 0 control bits. TL0 can count either CPU clock
cycles (divided by 4 or by 12) or high-to-low transitions on t0, as determined by the C/T
bit. The GATE function can be used to give counter enable control to the INT0_N signal.
Figure 10-4 : Timer 0 – Mode 3
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TH0 functions as an independent 8-bit counter. However, TH0 can count only CPU clock
cycles (divided by 4 or by 12). The Timer 1 control and flag bits (TR1 and TF1) are used
as the control and flag bits for TH0.
When Timer 0 is in mode 3, Timer 1 has limited usage because Timer 0 uses the Timer 1
control bit (TR1) and interrupt flag (TF1). Timer 1 can still be used for baud rate generation
and the Timer 1 count values are still available in the TL1 and TH1 registers.Control of
Timer 1 when Timer 0 is in mode 3 is through the Timer 1 mode bits. To turn Timer 1 on,
set Timer 1 to mode 0, 1, or 2. To turn Timer 1 off, set it to mode 3. The Timer 1 C/T bit
and T1M bit are still available to Timer 1. Therefore, Timer 1 can count CPU_clk/4,
CPU_clk/12, or high-to-low transitions on the t1 pin. The Timer 1 GATE function is also
available when Timer 0 is in mode 3.
10.8.2 Timer Rate Control
The default timer clock scheme for the nRF24E1 timers is twelve CPU clock cycles per
increment, the same as in the standard 8051. However, in the nRF24E1, the instruction
cycle is four clock cycles.
Using the default rate (twelve clocks per timer increment) allows existing application code
with real-time dependencies, such as baud rate, to operate properly. However, applications
that require fast timing can set the timers to increment every four clock cycles by setting bits
in the Clock Control register (CKCON) at SFR location 0x8E, described in Table 10-15 :
CKCON Register – SFR 0x.
The CKCON bits that control the timer clock rates are:
CKCON bit Counter/Timer
5
Timer 2
4
Timer 1
3
Timer 0
When a CKCON register bit is set to 1, the associated counter increments at four-clock
intervals. When a CKCON bit is cleared, the associated counter increments at twelve-clock
intervals. The timer controls are independent of each other. The default setting for all three
timers is 0; that is, twelve-clock intervals. These bits have no effect in counter mode.
Bit
CKCON.7,6
CKCON.5
CKCON.4
CKCON.3
CKCON.2–0
Function
Reserved
T2M – Timer 2 clock select. When T2M = 0, Timer 2 uses CPU_clk/12 (for
compatibility with 80C32); when T2M = 1, Timer 2 uses CPU_clk/4. This bit has no
effect when Timer 2 is configured for baud rate generation.
T1M – Timer 1 clock select. When T1M = 0, Timer 1 uses CPU_clk/12 (for
compatibility with 80C32); when T1M = 1, Timer 1 uses CPU_clk/4.
T0M – Timer 0 clock select. When T0M = 0, Timer 0 uses CPU_clk/12 (for
compatibility with 80C32); when T0M = 1, Timer 0 uses CPU_clk/4.
MD2, MD1, MD0 – Control the number of cycles to be used for external MOVX
instructions; number of cycles is 2 + { MD2, MD1, MD0}
Table 10-15 : CKCON Register – SFR 0x8E,
default initial data value is 0x01, i.e. MOVX takes 3 cycles.
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10.8.3 Timer 2
Timer 2 runs only in 16-bit mode and offers several capabilities not available with Timers 0
and 1. The modes available with Timer 2 are:
- 16-bit timer/counter
- 16-bit timer with capture
- 16-bit auto-reload timer/counter
- Baud-rate generator
The SFRs associated with Timer 2 are:
- T2CON – SFR 0xC8; refer to Table 10-16 : T2CON Register – SFR 0x
- RCAP2L – SFR 0xCA – Used to capture the TL2 value when Timer 2 is configured
for capture mode, or as the LSB of the 16-bit reload value when Timer 2 is configured for
auto-reload mode.
- RCAP2H – SFR 0xCB – Used to capture the TH2 value when Timer 2 is configured
for capture mode, or as the MSB of the 16-bit reload value when Timer 2 is configured for
auto-reload mode.
- TL2 – SFR 0xCC – Lower eight bits of the 16-bit count.
- TH2 – SFR 0xCD – Upper eight bits of the 16-bit count.
Bit
T2CON.7
T2CON.6
T2CON.5
T2CON.4
T2CON.3
T2CON.2
T2CON.1
T2CON.0
Function
TF2 - Timer 2 overflow flag. Hardware will set TF2 when Timer 2 overflows from 0xFFFF. TF2 must be
cleared to 0 by the software. TF2 will only be set to a 1 if RCLK and TCLK are both cleared to 0. Writing a
1 to TF2 forces a Timer 2 interrupt if enabled.
EXF2 - Timer 2 external flag. Hardware will set EXF2 when a reload or capture is caused by a high-to-low
transition on the t2ex pin, and EXEN2 is set. EXF2 must be cleared to 0 by the software. Writing a 1 to
EXF2 forces a Timer 2 interrupt if enabled.
RCLK - Receive clock flag. Determines whether Timer 1 or Timer 2 is used for Serial port timing of received
data in serial mode 1 or 3. RCLK = 1 selects Timer 2 overflow as the receive clock. RCLK = 0 selects Timer
1 overflow as the receive clock.
TCLK - Transmit clock flag. Determines whether Timer 1 or Timer 2 is used for Serial port timing of
transmit data in serial mode 1 or 3. TCLK =1 selects Timer 2 overflow as the transmit clock. TCLK = 0
selects Timer 1 overflow as the transmit clock.
EXEN2 - Timer 2 external enable. EXEN2 = 1 enables capture or reload to occur as a result of a high-to-low
transition on t2ex, if Timer 2 is not generating baud rates for the serial port. EXEN2 = 0 causes Timer 2 to
ignore all external events at t2ex.
TR2 - Timer 2 run control flag. TR2 = 1 starts Timer 2. TR2 = 0 stops Timer 2.
C/T2 - Counter/timer select. C/T2 = 0 selects a timer function for Timer 2. C/T2 = 1 selects a counter of
falling transitions on the t2 pin. When used as a timer, Timer 2 runs at four clocks per increment or twelve
clocks per increment as programmed by CKCON.5, in all modes except baud-rate generator mode. When
used in baud-rate generator mode, Timer 2 runs at two clocks per increment, independent of the state of
CKCON.5.
CP/RL2 - Capture/reload flag. When CP/RL2 = 1, Timer 2 captures occur on high-to-low transitions of
t2ex, if EXEN2 = 1. When CP/RL2 = 0, auto-reloads occur when Timer 2 overflows or when high-to-low
transitions occur on t2ex, if EXEN2 = 1. If either RCLK or TCLK is set to 1, CP/RL2 will not function, and
Timer 2 will operate in auto-reload mode following each overflow.
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Table 10-16 : T2CON Register – SFR 0xC8
10.8.3.1 Timer 2 Mode Control
Table 10-17 summarizes how the SFR bits determine the Timer 2 mode.
RCLK TCLK CP/RL2
TR2
Mode
0
0
1
1
16-bit timer/counter with capture
0
0
0
1
16-bit timer/counter with auto-reload
1
X
X
1
Baud-rate generator
X
1
X
1
Baud-rate generator
X
X
X
0
Off
Table 10-17 : Timer 2 Mode Control Summary
10.8.3.2 16-Bit Timer/Counter Mode
Figure 10-5 : Timer 2 – Timer/Counter with Capture illustrates how Timer 2 operates in
timer/counter mode with the optional capture feature. The C/T2 bit determines whether the
16-bit counter counts clock cycles (divided by 4 or 12), or high-to-low transitions on the t2
pin. The TR2 bit enables the counter. When the count increments from 0xFFFF, the TF2
flag is set, and t2_out goes high for one clock cycle.
Figure 10-5 : Timer 2 – Timer/Counter with Capture
10.8.3.3 16-Bit Timer/Counter Mode with Capture
The Timer 2 capture mode, illustrated in Figure 10-5 : Timer 2 – Timer/Counter with
Capture, is the same as the 16-bit timer/counter mode, with the addition of the capture
registers and control signals. The CP/RL2 bit in the T2CON SFR enables the capture
feature. When CP/RL2 = 1, a high-to-low transition on t2ex when EXEN2 = 1 causes the
Timer 2 value to be loaded into the capture registers (RCAP2L and RCAP2H).
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10.8.3.4 16-Bit Timer/Counter Mode with Auto-Reload
When CP/RL2 = 0, Timer 2 is configured for the auto-reload mode illustrated in Figure
10-6 : Timer 2 – Timer/Counter with Auto-Reload. Control of counter input is the same as
for the other 16-bit counter modes. When the count increments from 0xFFFF, Timer 2 sets
the TF2 flag and the starting value is reloaded into TL2 and TH2. The software must
preload the starting value into the RCAP2L and RCAP2H registers.
When Timer 2 is in auto-reload mode, a reload can be forced by a high-to-low transition on
the t2ex pin, if enabled by EXEN2 = 1.
Figure 10-6 : Timer 2 – Timer/Counter with Auto-Reload
10.8.3.5 Baud Rate Generator Mode
Setting either RCLK or TCLK to 1 configures Timer 2 to generate baud rates for Serial
port in serial mode 1 or 3. In baud-rate generator mode, Timer 2 functions in auto-reload
mode. However, instead of setting the TF2 flag, the counter overflow generates a shift clock
for the serial port function. As in normal auto-reload mode, the overflow also causes the
preloaded start value in the RCAP2L and RCAP2H registers to be reloaded into the TL2
and TH2 registers.
When either TCLK = 1 or RCLK = 1, Timer 2 is forced into auto-reload operation,
regardless of the state of the CP/RL2 bit.
When operating as a baud rate generator, Timer 2 does not set the TF2 bit. In this mode, a
Timer 2 interrupt can be generated only by a high-to-low transition on the t2ex pin setting
the EXF2 bit, and only if enabled by EXEN2 = 1.The counter time base in baud-rate
generator mode is CPU_clk/2. To use an external clock source, set C/T2 to 1 and apply the
desired clock source to the t2 pin.
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Figure 10-7 : Timer 2 – Baud Rate Generator Mode
10.9 Serial Interface
The nRF24E1 is configured with one serial port, which is identical in operation to the
standard 8051 serial port. The two serial port pins rxd and txd are available as alternate
functions of P0.1 and P0.2, for details please see ch. 3 I/O PORTS.
The serial port can operate in synchronous or asynchronous mode. In synchronous mode,
the nRF24E1 generates the serial clock and the serial port operates in half-duplex mode. In
asynchronous mode, the serial port operates in full-duplex mode. In all modes, the
nRF24E1 buffers receive data in a holding register, enabling the UART to receive an
incoming word before the software has read the previous value.
The serial port can operate in one of four modes, as outlined in Table 10-18
Mode
Sync/As Baud Clock
ync
Data Bits
Start/ Stop
9th Bit Function
0
Sync
8
None
None
1
Async
8
None
2
Async
3
Async
1 start,
1 stop
1 start,
1 stop
1 start,
1 stop
CPU_clk/4 or
CPU_clk/12
Timer 1 or Timer
2
CPU_clk/32 or
CPU_clk/64
Timer 1 or Timer
2
9
9
0, 1, parity
0, 1, parity
Table 10-18 : Serial Port Modes
The SFRs associated with the serial port are:
- SCON – SFR 0x98 – Serial port control (Table 10-19)
- SBUF – SFR 0x99 – Serial port buffer
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Bit
Function
SCON.7
SCON.6
SM0 - Serial port mode bit 0.
SM1 - Serial port mode bit 1, decoded as:
SM0 SM1 Mode
0
0
0
0
1
1
1
0
2
1
1
3
SM2 - Multiprocessor communication enable. In modes 2 and 3, SM2 enables the
multiprocessor communication feature. If SM2 = 1 in mode 2 or 3, RI will not be
activated if the received 9th bit is 0. If SM2 = 1 in mode 1, RI will be activated only if a
valid stop is received. In mode 0, SM2 establishes the baud rate: when SM2 = 0, the
baud rate is CPU_clk/12; when
SM2 = 1, the baud rate is CPU_clk/4.
REN - Receive enable. When REN = 1, reception is enabled.
TB8 - Defines the state of the 9th data bit transmitted in modes 2 and 3.
RB8 - In modes 2 and 3, RB8 indicates the state of the 9th bit received. In mode 1,
RB8 indicates the state of the received stop bit. In mode 0, RB8 is
not used.
TI - Transmit interrupt flag. Indicates that the transmit data word has been shifted
out. In mode 0, TI is set at the end of the 8th data bit. In all other modes, TI is set
when the stop bit is placed on the txd pin. TI must be cleared by the software.
RI – Receive interrupt flag. Indicates that a serial data word has been
received. In mode 0, RI is set at the end of the 8th data bit. In mode 1, RI
is set after the last sample of the incoming stop bit, subject to the state
of SM2.In modes 2 and 3, RI is set at the end of the last sample of RB8. RI
must be cleared by the software.
SCON.5
SCON.4
SCON.3
SCON.2
SCON.1
SCON.0
Table 10-19 : SCON Register – SFR 0x98
10.9.1 Mode 0
Serial mode 0 provides synchronous, half-duplex serial communication. For Serial
Port 0, both serial data input and output occur on rxd pin, and txd provides the shift clock
for both transmit and receive. The rxd and txd pins are alternate function bits of Port 0,
please also see Table 3-2 : Port 0 (P0) functions for port and pin configuration. The lack of
open drain ports on nRF24E1 makes it a programmer responsibility to control the direction
of the rxd pin.
The serial mode 0 baud rate is either CPU_clk/12 or CPU_clk/4, depending on the state of
the SM2. When SM2 = 0, the baud rate is CPU_clk/12; when SM2 = 1, the baud rate is
CPU_clk/4.
Mode 0 operation is identical to the standard 8051. Data transmission begins when an
instruction writes to the SBUF SFR. The UART shifts the data out, LSB first, at the
selected baud rate, until the 8-bit value has been shifted out.
Mode 0 data reception begins when the REN bit is set and the RI bit is cleared in the
corresponding SCON SFR. The shift clock is activated and the UART shifts data in on
each rising edge of the shift clock until eight bits have been received. One machine cycle
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after the 8th bit is shifted in, the RI bit is set and reception stops until the software clears the
RI bit.
Figure 10-8 : Serial Port Mode 0 receive timing for low-speed (CPU_clk/12) operation.
Figure 10-9 : Serial Port Mode 0 receive timing for high-speed (CPU_clk/4) operation
Figure 10-10 : Serial Port Mode 0 transmit timing for high-speed (CPU_clk/4)
operation
Figure 10-11 : Serial Port Mode 0 transmit timing for high-speed (CPU_clk/4)
operation
10.9.2 Mode 1
Mode 1 provides standard asynchronous, full-duplex communication, using a total
of ten bits: one start bit, eight data bits, and one stop bit. For receive operations, the stop bit
is stored in RB8. Data bits are received and transmitted LSB first.
10.9.2.1 Mode 1 Baud Rate
The mode 1 baud rate is a function of timer overflow. Serial port can use either
Timer 1 or Timer 2 to generate baud rates. Each time the timer increments from its maximum
count (0xFF for Timer 1 or 0xFFFF for Timer 2), a clock is sent to the baud-rate circuit.
The clock is then divided by 16 to generate the baud rate. When using Timer 1, the SMOD
bit selects whether or not to divide the Timer 1 rollover rate by 2. Therefore, when using
Timer 1, the baud rate is determinedby the equation:
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2 SMOD
x Timer 1 Overflow
32
SMOD is SFR bit PCON.7
Baud Rate =
When using Timer 2, the baud rate is determined by the equation:
Timer 2 Overflow
Baud Rate =
16
To use Timer 1 as the baud-rate generator, it is best to use Timer 1 mode 2 (8-bit counter
with auto-reload), although any counter mode can be used. The Timer 1 reload value is
stored in the TH1 register, which makes the complete formula for Timer 1:
2 SMOD
clk
Baud Rate =
x
32
4 x (256 - TH1)
The 4 in the denominator in the above equation can be obtained by setting the T1M bit in
the CKCON SFR. To derive the required TH1 value from a known baud rate (when TM1
= 0), use the equation:
TH1 = 256 -
2 SMOD ∗ clk
128 ∗ Baud Rate
You can also achieve very low serial port baud rates from Timer 1 by enabling the
Timer 1 interrupt, configuring Timer 1 to mode 1, and using the Timer 1 interrupt to
initiate a 16-bit software reload. Table Table 10-20 lists sample reload values for a variety
of common serial port baud rates.
Desired
Baud Rate
SMOD
C/T
Timer 1
Mode
TH1 Value
TH1 Value
for 16 MHz
for 8 MHz
CPU clk
CPU clk
19.2 Kb/s
1
0
2
0xF3
9.6 Kb/s
1
0
2
0xE6
0xF3
4.8 Kb/s
1
0
2
0XcC
0xE6
2.4 Kb/s
1
0
2
0x98
0xCC
1.2 Kb/s
1
0
2
0x30
0x98
Table 10-20 : Timer 1 Reload Values for Serial Port Mode 1 Baud Rates
To use Timer 2 as the baud-rate generator, configure Timer 2 in auto-reload mode and
set the TCLK and/or RCLK bits in the T2CON SFR. TCLK selects Timer 2 as the
baud-rate generator for the transmitter; RCLK selects Timer 2 as the baud-rate generator
for the receiver. The 16-bit reload value for Timer 2 is stored in the RCAP2L and RCA2H
SFRs, which makes the equation for the Timer 2 baud rate:
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Baud Rate =
clk
32 x (65536 - {RCAP2H, RCAP2L})
where RCAP2H,RCAP2L is the content of RCAP2H and RCAP2L taken as a 16-bit
unsigned number. The 32 in the denominator is the result of the CPU_clk signal being
divided by 2 and the Timer 2 overflow being divided by 16. Setting TCLK or RCLK to 1
automatically causes the CPU_clk signal to be divided by 2, as shown in Figure 10-7 :
Timer 2 – Baud Rate Generator Mode, instead of the 4 or 12 determined by the T2M bit in
the CKCON SFR.
To derive the required RCAP2H and RCAP2L values from a known baud rate, use the
equation:
clk
RCAP2H,RCAP2L = 65536 –
32 x Baud Rate
Table Table 10-21 lists sample values of RCAP2L and RCAP2H for a variety of
desired baud rates.
Baud Rate
C/ 16 MHz CPU clk
T2 RCAP2H
RCAP2L
57.6 Kb/s
0
0xFF
0xF7
19.2 Kb/s
0
0xFF
0xE6
9.6 Kb/s
0
0xFF
0xCC
4.8 Kb/s
0
0xFF
0x98
2.4 Kb/s
0
0xFF
0x30
1.2 Kb/s
0
0xFE
0x5F
Table 10-21 : Timer 2 Reload Values for Serial Port Mode 1 Baud Rates
When either RCLK or TCLK is set, the TF2 flag will not be set on a Timer 2
rollover, and the t2ex reload trigger is disabled.
10.9.2.2 Mode 1 Transmit
Figure 10-12 illustrates the mode 1 transmit timing. In mode 1, the UART begins
transmitting after the first rollover of the divide-by-16 counter after the software writes to the
SBUF register. The UART transmits data on the txd pin in the following order: start bit,
eight data bits (LSB first), stop bit. The TI bit is set two clock cycles after the stop bit is
transmitted.
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Figure 10-12 : Serial port Mode 1 Transmit Timing
10.9.2.3 Mode 1 Receive
Figure 18 illustrates the mode 1 receive timing. Reception begins at the falling edge of a start
bit received on rxd_in, when enabled by the REN bit. For this purpose, rxd_in is
sampled sixteen times per bit for any baud rate. When a falling edge of a start bit is
detected, the divide-by-16 counter used to generate the receive clock is reset to align the
counter rollover to the bit boundaries.
Figure 10-13 : Serial port Mode 1 Receive Timing
For noise rejection, the serial port establishes the content of each received bit by a
majority decision of three consecutive samples in the middle of each bit time. This is
especially true for the start bit. If the falling edge on rxd_in is not verified by a majority
decision of three consecutive samples (low), then the serial port stops reception and waits
for another falling edge on rxd_in.
At the middle of the stop bit time, the serial port checks for the following conditions:
- RI = 0
- If SM2 = 1, the state of the stop bit is 1
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(if SM2 = 0, the state of the stop bit does not matter)
If the above conditions are met, the serial port then writes the received byte to the SBUF
register, loads the stop bit into RB8, and sets the RI bit. If the above conditions are not
met, the received data is lost, the SBUF register and RB8 bit are not loaded, and the RI bit
is not set. After the middle of the stop bit time, the serial port waits for another high-to-low
transition on the rxd_in pin.
Mode 1 operation is identical to that of the standard 8051 when Timers 1 and 2 use
CPU_clk/12 (the default).
10.9.3 Mode 2
Mode 2 provides asynchronous, full-duplex communication, using a total of
eleven bits:
- One start bit
- Eight data bits
- One programmable 9th bit
- One stop bit
The data bits are transmitted and received LSB first. For transmission, the 9th bit
is determined by the value in TB8. To use the 9th bit as a parity bit, move the
value of the P bit (SFR PSW.0) to TB8.
The mode 2 baud rate is either CPU_clk/32 or CPU_clk/64, as determined by the
SMOD bit. The formula for the mode 2 baud rate is:
Baud Rate =
2 SMOD ∗ clk
64
Mode 2 operation is identical to the standard 8051.
10.9.3.1 Mode 2 Transmit
Figure 10-14 illustrates the mode 2 transmit timing. Transmission begins after the first
rollover of the divide-by-16 counter following a software write to SBUF . The UART shifts
data out on the txd pin in the following order: start bit, data bits (LSB first), 9th bit, stop bit.
The TI bit is set when the stop bit is placed on the txd pin.
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Figure 10-14 : Serial port Mode 2 Transmit Timing
10.9.3.2 Mode 2 Receive
Figure 10-15 illustrates the mode 2 receive timing. Reception begins at the falling edge of a
start bit received on rxd_in, when enabled by the REN bit. For this purpose, rxd_in is
sampled sixteen times per bit for any baud rate.When a falling edge of a start bit is detected,
the divide-by-16 counter used to generate the receive clock is reset to align the counter
rollover to the bit boundaries.
Figure 10-15 : Serial port Mode 2 Receive Timing
For noise rejection, the serial port establishes the content of each received bit by a
majority decision of three consecutive samples in the middle of each bit time. This is
especially true for the start bit. If the falling edge on rxd_in is not verified by a majority
decision of three consecutive samples (low), then the serial port stops reception and waits
for another falling edge on rxd_in.
At the middle of the stop bit time, the serial port checks for the following conditions:
- RI = 0
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- If SM2 = 1, the state of the stop bit is 1
(if SM2 = 0, the state of the stop bit does not matter)
If the above conditions are met, the serial port then writes the received byte to the
SBUF register, loads the 9th received bit into RB8, and sets the RI bit. If the above
conditions are not met, the received data is lost, the SBUF register and RB8 bit are not
loaded, and the RI bit is not set. After the middle of the stop bit time, the serial port waits
for another high-to-low transition on the rxd_in.
10.9.4 Mode 3
Mode 3 provides asynchronous, full-duplex communication, using a total of eleven bits:
- One start bit
- Eight data bits
- One programmable 9th bit
- One stop bit; the data bits are transmitted and received LSB first
The mode 3 transmit and receive operations are identical to mode 2. The mode 3 baud
rate generation is identical to mode 1. That is, mode 3 is a combination of mode 2
protocol and mode 1 baud rate. Figure 10-16 illustrates the mode 3 transmit timing. Mode 3
operation is identical to that of the standard 8051 when Timers 1 and 2 use CPU_clk/12
(the default).
Figure 10-16 : Serial port Mode 3 Transmit Timing
Figure 10-17 illustrates the mode 3 receive timing.
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Figure 10-17 : Serial port Mode 3 Receive Timing
10.9.5 Multiprocessor Communications
The multiprocessor communication feature is enabled in modes 2 and 3 when the SM2 bit is
set in the SCON SFR for a serial port. In multiprocessor communication mode, the 9th bit
received is stored in RB8 and, after the stop bit is received, the serial port interrupt is
activated only if RB8 = 1. A typical use for the multiprocessor communication feature is
when a master wants to send a block of data to one of several slaves. The master first
transmits an address byte that identifies the target slave. When transmitting an address byte,
the master sets the 9th bit to 1; for data bytes, the 9th bit is 0.
When SM2 = 1, no slave will be interrupted by a data byte. However, an address byte
interrupts all slaves so that each slave can examine the received address byte to determine
whether that slave is being addressed. Address decoding must be done by software during
the interrupt service routine. The addressed slave clears its SM2 bit and prepares to receive
the data bytes. The slaves that are not being addressed leave the SM2 bit set and ignore the
incoming data bytes.
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11 ELECTRICAL SPECIFICATIONS
Conditions: VDD = +3V, VSS = 0V, TA = - 40ºC to + 85ºC
Symbol Parameter (condition)
Notes Min.
Operating conditions
Typ.
Max.
Units
VDD
TEMP
3.0
+27
3.6
+85
V
ºC
VDD
0.3
V
V
pF
nA
VDD- 0.3
VSS
VDD
0.3
V
V
4
1
20
5.5
MHz
KHz
mA
µA
2524
MHz
kHz
kbps
MHz
Supply voltage
Operating Temperature
1.9
-40
Digital input pin
VIH
VIL
Ci
IiL
HIGH level input voltage
LOW level input voltage
input capacitance
input leakage current
VDD- 0.3
VSS
0.55
0.08
Digital output pin
VOH
VOL
HIGH level output voltage (IOH=0.5mA)
LOW level output voltage (IOL=-0.5mA)
Microcontroller
fXTAL
fLP_OSC
IVDD_MCU
IVDD_pwd
Crystal frequency
Low power RC oscillator frequency
Supply current @16MHz @3V
Average Supply current in power down
2)
I
3
2
General RF conditions
fOP
∆f
RGFSK
FCHANNEL
Operating frequency
Frequency deviation
Data rate ShockBurst™
Channel spacing
1)
2400
±156
>0
1000
1
Transmitter operation
PRF
PRFC
PRFCR
PBW
PRF2
PRF3
IVDD_TX0
IVDD_TX20
Maximum Output Power
4)
RF Power Control Range
RF Power Control Range Resolution
20dB Bandwidth for Modulated Carrier
2nd Adjacent Channel Transmit Power 2MHz
3rd Adjacent Channel Transmit Power 3MHz
Supply current @ 0dBm output power
5)
Supply current @ -20dBm output power
5)
16
0
20
+4
13
9
dBm
dB
dB
kHz
dBm
dBm
mA
mA
18
19
23
25
-90
-80
10
-20
-37
-43
-41
mA
mA
mA
mA
dBm
dBm
dB
dB
dB
dB
dB
±3
1000
-20
-40
Receiver operation
IVDD_RX
IVDD_RX
IVDD_RX2
IVDD_RX2
RXSENS
RXSENS
C/ICO
C/I1ST
C/I2ND
C/I3RD
RXB
Supply current one receiver @250kbps
Supply current one receiver @1000kbps
Supply current two receivers @250kbps
Supply current two receivers @1000kbps
Sensitivity at 0.1%BER (@250kbps)
Sensitivity at 0.1%BER (@1000kbps)
C/I Co-channel
1st Adjacent Channel Selectivity C/I 1MHz
2nd Adjacent Channel Selectivity C/I 2MHz
3rd Adjacent Channel Selectivity C/I 3MHz
Blocking Data Channel 2
3)
3)
3)
3)
6)
6)
6)
6)
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PRODUCT SPECIFICATION
nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
ADC operation
DNL
INL
SNR
VOS
εG
SNR
SFDR
VBG
Differential Nonlinearity fIN = 0.9991 kHz
Integral Nonlinearity fIN = 0.9991 kHz
Signal to Noise Ratio (DC input)
Midscale offset
Gain Error
Signal to Noise Ratio (without harmonics) fIN
= 10 kHz
Spurious Free Dynamic Range fIN = 10 kHz
Internal reference
Internal reference voltage drift
Reference voltage input (external ref)
6 bit conversion
8 bit conversion
10 bit conversion
12 bit conversion
Supply current ADC operation
Start-up time from ADC Power down
I
I
V
I
I
V
V
I
V
I
IV
IV
IV
IV
I
I
53
1.1
±0.5
±0.75
59
±1
±1
58
65
1.22
100
LSB
LSB
dBFS
%FS
%FS
dBFS
1.3
dB
V
ppm/°C
V
SPS
SPS
SPS
SPS
mA
µs
VFS
0.8
1.5
FS6
fXTAL / 160
fXTAL / 128
FS8
fXTAL / 192
fXTAL / 160
FS10
fXTAL / 224
fXTAL / 192
FS12
fXTAL / 256
fXTAL / 224
IADC
1
t NPD
15
NOTES:
1) Usable band is determined by local regulations
2) The crystal frequency may be chosen from 5 different values (4, 8, 12, 16, and 20MHz) which are specified in
the nRF2401 configuration word, please seeTable 14-2 Crystal specification of the nRF24E1. 16MHz is
required for 1Mbps operation.
3) Current for nRF2401 RF subsystem only.
4) Antenna load impedance = 100Ω+j175Ω
5) Current for nRF2401 RF subsystem only. Antenna load impedance = 100Ω+j175Ω. Effective data rate
250kbps or 1Mbps.
6) 250kbps.
I ) Test Level I: 100% production tested at +25°C
II ) Test Level II: 100% production tested at +25°C and sample tested at specified temperatures
III ) Test Level III: Sample tested only
IV ) Test Level IV: Parameter is guaranteed by design and characterization testing
V ) Test Level V: Parameter is typical value only
VI) Test Level VI: 100% production tested at +25°C. Guaranteed by design and characterization testing for
industrial temperature range
Table 11-1 : nRF24E1 Electrical specifications
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12 PACKAGE OUTLINE
12.1 GREEN PACKAGE OUTLINE
nRF24E1G uses the GREEN QFN36 6x6 package, punch type with matt tin plating. Dimensions are in
mm.
Package
Type
Green
QFN36
(6x6 mm)
Min
typ.
Max
A
A1
A2
b
D/E
D1/E1
e
J
K
L
R
0.8
0.0
0.02
0.05
0.65
0.18
0.23
0.3
6 BSC
5.75 BSC
0.5
BSC
4.47
4.57
4.67
4.47
4.57
4.67
0.3
0.4
0.5
1.735
1.835
1.935
0.9
0.69
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PRODUCT SPECIFICATION
nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
Figure 12-1 : nRF24E1G GREEN Package outline.
12.2
PACKAGE OUTLINE, saw type
nRF24E1 uses the QFN 36LD 6x6 Saw type package., with SnPb plating. Dimensions are in mm.
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PRODUCT SPECIFICATION
nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
Package
Type
QFN36
(6x6 mm)
Min
typ.
Max
A
A1
A2
b
D
E
e
J
K
L
0.8
0.0
0.75
0.2
0.25
0.3
6 BSC
6 BSC
0.5 BSC
4.47
4.57
4.67
4.47
4.57
4.67
0.35
0.4
0.45
1
0.05
1
Figure 12-2 : nRF24E1 package outline.
13 ABSOLUTE MAXIMUM RATINGS
L
Supply voltages
VDD ............................ - 0.3V to + 3.6V
VSS ...................................................0V
Input voltage
For analog pins, AIN0 to AIN7 and AREF :
VIA ................................. - 0.3V to 2.0 V
For all other pins :
VI ........................- 0.3V to VDD + 0.3V
Output voltage
VO .......................- 0.3V to VDD + 0.3V
Total Power Dissipation
PD (TA=85°C)...............................60mW
Temperatures
Operating Temperature…. - 40°C to + 85°C
Storage Temperature….… - 40°C to + 125°C
Note: Stress exceeding one or more of the limiting values may cause permanent
damage to the device.
13.1.1 ATTENTION!
Electrostatic Sensitive Device
Observe Precaution for handling.
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PRODUCT SPECIFICATION
nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
14 Peripheral RF Information
14.1.1 Antenna output
The ANT1 & ANT2 output pins provide a balanced RF output to the antenna. The pins
must have a DC path to VDD, either via a RF choke or via the center point in a dipole
antenna. The load impedance seen between the ANT1/ANT2 outputs should be in the
range 200-700Ω. A load of 100Ω+j175Ω is recommended for maximum output power
(0dBm). Lower load impedance (for instance 50 Ω) can be obtained by fitting a simple
matching network.
14.1.2 Output Power adjustment
Power setting bits of
configuring word
RF output power
DC current
consumption
11
0 dBm ±3dB
16.0 mA
10
-5 dBm ±3dB
13.5 mA
01
-10 dBm ±3dB
12.4 mA
00
-20 dBm ±3dB
11.8 mA
Conditions: VDD = 3.0V, VSS = 0V, T A = 27ºC, Load impedance = 100Ω+j175Ω.
Table 14-1 RF output power setting for the nRF24E1.
14.1.3 Crystal Specification
Tolerance includes initially accuracy and tolerance over temperature and aging.
Frequency
4 MHz
8 MHz
12 MHz
16 MHz
20 MHz
CL
12pF
12pF
12pF
12pF
12pF
ESR
C0max
Tolerance
150 Ω
100 Ω
100 Ω
100 Ω
100 Ω
7.0pF
7.0pF
7.0pF
7.0pF
7.0pF
±30ppm
±30ppm
±30ppm
±30ppm
±30ppm
Table 14-2 Crystal specification of the nRF24E1.
To achieve a crystal oscillator solution with low power consumption and fast start-up time, it
is recommended to specify the crystal with a low value of crystal load capacitance.
Specifying CL=12pF is OK, but it is possible to use up to 16pF. Specifying a lower value of
crystal parallel equivalent capacitance, C0 will also work, but this can increase the price of
the crystal itself. Typically C0=1.5pF at a crystal specified for C0_max=7.0pF.
The selected frequency value must also be set into the nRF2401 configuration word, please
see Table 4-12 Crystal frequency setting.
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14.2 PCB layout and de-coupling guidelines
A well-designed PCB is necessary to achieve good RF performance. Keep in mind that a
poor layout may lead to loss of performance, or even functionality, if due care is not taken.
A fully qualified RF-layout for the nRF24E1 and its surrounding components, including
matching networks, can be downloaded from www.nordicsemi.no.
A PCB with a minimum of two layers including a ground plane is recommended for optimum
performance. The nRF24E1 DC supply voltage should be de-coupled as close as possible
to the VDD pins with high performance RF capacitors, see Table 15-1. It is preferable to
mount a large surface mount capacitor (e.g. 4.7µF tantalum) in parallel with the smaller value
capacitors. The nRF24E1 supply voltage should be filtered and routed separately from the
supply voltages of any digital circuitry.
Long power supply lines on the PCB should be avoided. All device grounds, VDD
connections and VDD bypass capacitors must be connected as close as possible to the
nRF24E1 IC. For a PCB with a topside RF ground plane, the VSS pins should be
connected directly to the ground plane. For a PCB with a bottom ground plane, the best
technique is to have via holes as close as possible to the VSS pads. One via hole should be
used for each VSS pin.
Full swing digital data or control signals should not be routed close to the crystal or the
power supply lines.
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PRODUCT SPECIFICATION
nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
15 Application example
15.1 nRF24E1 with single ended matching network
xxx
R5
AREF
1k
C14
1nF
AIN7
AIN6
AIN5
AIN4
AIN3
AIN2
AIN1
AIN0
C15
100nF
VDD
R2
22k
36
35
34
33
32
31
30
29
28
C6
10nF
P1.2
AIN1
AIN2
VSS
VDD
VSS
AIN3
AIN4
AREF
C5
1nF
DIN1
DIO0
DIO1
DIO2
DIO3
DIO4
DIO5
DIO6
DIO7
DIO8
DIO9
nRF24E1
10
11
12
13
14
15
16
17
18
VDD
VDD
AIN0
DVDD2
P1.0
P1.1
P0.0
P0.1
P0.2
P0.3
P0.4
P0.5
P0.6
P0.7
DVDD
VSS
XC2
XC1
VDD_PA
xxx
1
2
3
4
5
6
7
8
9
VDD
IREF
AIN5
AIN6
AIN7
VSS
VDD
VSS_PA
ANT2
ANT1
27
26
25
24
23
22
21
20
19
C10
1.0pF
L4
5.6nH
C11
L3
5.6nH
L1
3.3nH
C12
RF I/O
2.2pF
xxx
4.7pF
L2
10nH
C9
1.0pF
U1
nRF24E1
R3
10k
U2
1
2
3
4
R4
10k
CS
SO
WP
VSS
25XX320
VDD
VCC
HOLD
SCK
SI
8
7
6
5
X1
C13
10nF
C7
1nF
C8
33nF
C3
4.7pF
C4
2.2nF
16 MHz
R1
1M
C1
22pF
C2
22pF
xxx
Figure 15-1 nRF24E1 schematic for RF layout with single end 50Ω antenna
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PRODUCT SPECIFICATION
nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
Component
C1
C2
C3
C4
C5
C6
C7
C8
C9
C10
C11
C12
C13
C14
C15
L1
L2
L3
L4
R1
R2
R3
R4
R5
U1
X1
U2
Description
Capacitor ceramic, 50V, NPO
Capacitor ceramic, 50V, NPO
Capacitor ceramic, 50V, NPO
Capacitor ceramic, 50V, X7R
Capacitor ceramic, 50V, X7R
Capacitor ceramic, 50V, X7R
Capacitor ceramic, 50V, X7R
Capacitor ceramic, 50V, X7R
Capacitor ceramic, 50V, NPO
Capacitor ceramic, 50V, NPO
Capacitor ceramic, 50V, NPO
Capacitor ceramic, 50V, NPO
Capacitor ceramic, 50V, X7R
Capacitor ceramic, 50V, X7R
Capacitor ceramic, 50V, X7R
Inductor, wire wound 2)
Inductor, wire wound 2)
Inductor, wire wound 2)
Inductor, wire wound 2)
Resistor
Resistor
Resistor
Resistor
Resistor
nRF24E1 transceiver
Crystal, CL = 12pF,
ESR < 100 ohm
4 kbyte serial EEPROM with SPI
interface
Size
Value
Tolerance
Units
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
0603
QFN36 / 6x6
LxWxH =
4.0x2.5x0.8
SO8
22
22
4.7
2.2
1.0
10
1
33
1.0
1.0
2.2
4.7
10
1.0
100
3.3
10
5.6
5.6
1.0
22
10
10
1
nRF24E1
161)
±5%
±5%
±5%
±10%
±10%
±10%
±10%
±10%
± 0.1 pF
± 0.1 pF
± 0.25 pF
± 0.25 pF
±10%
±10%
±10%
± 5%
± 5%
± 5%
± 5%
±5%
±1%
±5%
±5%
±5%
pF
pF
pF
nF
nF
nF
nF
nF
pF
pF
pF
pF
nF
nF
nF
nH
nH
nH
nH
MΩ
kΩ
kΩ
kΩ
kΩ
+/- 30 ppm
MHz
2XX320
Table 15-1 Recommended components (BOM) in nRF24E1 with antenna matching
network
2)
Wire wound inductors are recommended, other can be used if their self-resonant
frequency (SRF) is > 2.7 GHz
1)
nRF24E1 can operate at several crystal frequencies, please refer to 108.
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15.2 PCB layout example
Figure 15-2 shows a PCB layout example for the application schematic in Figure 15-1.
A double-sided FR-4 board of 1.6mm thickness is used. This PCB has a ground plane on
the bottom layer. Additionally, there are ground areas on the component side of the board
to ensure sufficient grounding of critical components. A large number of via holes connect
the top layer ground areas to the bottom layer ground plane.
No components in bottom layer
Top silk screen
Top view
Bottom view
Figure 15-2 nRF24E1 RF layout with single ended connection to 50Ω antenna and 0603
size passive components
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nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
16 Table of Figures
Figure 1-1 nRF24E1 block diagram plus external components ..........................................5
Figure 3-1 : SPI interface timing......................................................................................19
Figure 4-1 : Transceiver interface....................................................................................22
Figure 4-2Clocking in data with CPU and sending with ShockBurst technology............23
Figure 4-3 RF Current consumption with & without ShockBurst technology.................24
Figure 4-4 Flow Chart ShockBurst™ Transmit of nRF2401 subsystem...........................25
Figure 4-5 Flow Chart ShockBurst™ Receive of nRF2401 subsystem............................26
Figure 4-6 Simultaneous 2 channel receive on nRF24E1 .................................................27
Figure 4-7 DuoCeiverTM with two simultaneously independent receive channels...............28
Figure 4-8Data packet set-up.........................................................................................29
Figure 4-9 Data Package Diagram..................................................................................41
Figure 4-10 Timing diagram for power down (or VDD off) to configuration mode for
nRF2401 subsystem................................................................................................42
Figure 4-11 Power down (or VDD off) to active mode...................................................43
Figure 4-12 Timing diagram for configuration of nRF2401 subsystem..............................44
Figure 4-13 Timing of ShockBurst™ in TX ....................................................................45
Figure 4-14 Timing of ShockBurst™ in RX....................................................................46
Figure 5-1 : Block diagram of A/D converter..................................................................48
Figure 5-2 Typical use of A/D with 2 ratiometric inputs...................................................51
Figure 5-3 : Timing diagram single step conversion. .........................................................52
Figure 5-4 : Timing diagram continuous mode conversion. ...............................................53
Figure 8-18-2 : RTC and watchdog block diagram.........................................................63
Figure 10-1 : Memory Map and Organization.................................................................68
Figure 10-2 : Timer 0/1 – Modes 0 and 1.......................................................................86
Figure 10-3 : Timer 0/1 – Mode 2..................................................................................87
Figure 10-4 : Timer 0 – Mode 3.....................................................................................87
Figure 10-5 : Timer 2 – Timer/Counter with Capture.......................................................90
Figure 10-6 : Timer 2 – Timer/Counter with Auto-Reload...............................................91
Figure 10-7 : Timer 2 – Baud Rate Generator Mode.......................................................92
Figure 10-8 : Serial Port Mode 0 receive timing for low-speed (CPU_clk/12) operation..94
Figure 10-9 : Serial Port Mode 0 receive timing for high-speed (CPU_clk/4) operation...94
Figure 10-10 : Serial Port Mode 0 transmit timing for high-speed (CPU_clk/4)................94
Figure 10-11 : Serial Port Mode 0 transmit timing for high-speed (CPU_clk/4)................94
Figure 10-12 : Serial port Mode 1 Transmit Timing.........................................................97
Figure 10-13 : Serial port Mode 1 Receive Timing..........................................................97
Figure 10-14 : Serial port Mode 2 Transmit Timing.........................................................99
Figure 10-15 : Serial port Mode 2 Receive Timing..........................................................99
Figure 10-16 : Serial port Mode 3 Transmit Timing.......................................................100
Figure 10-17 : Serial port Mode 3 Receive Timing........................................................101
Figure 12-1 : nRF24E1G GREEN Package outline.......................................................105
Figure 12-2 : nRF24E1 package outline........................................................................106
Figure 15-1 nRF24E1 schematic for RF layout with single end 50Ω antenna .................110
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nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
Figure 15-2 nRF24E1 RF layout with single ended connection to 50Ω antenna and 0603
size passive components........................................................................................112
17 Table of Tables
Table 1-1 : nRF24E1 quick reference data .......................................................................4
Table 1-2 : nRF24E1 ordering information........................................................................4
Table 1-3 : nRF24E1 pin function.....................................................................................7
Table 2-1 : SFR Register map........................................................................................11
Table 3-1 : Port functions ...............................................................................................14
Table 3-2 : Port 0 (P0) functions ....................................................................................15
Table 3-3 : Port 0 control and data SFR-registers...........................................................15
Table 3-4 : Port 1 (P1) functions ....................................................................................16
Table 3-5 : Port 1 control and data SFR-registers...........................................................17
Table 3-6 : SPI control and data SFR-registers...............................................................18
Table 4-1 : nRF2401 2.4GHz transceiver subsystem control registers - SFR 0xA0 and
0xB3.......................................................................................................................20
Table 4-2 : RADIO register - SFR 0xA0, default initial data value is 0x80.......................21
Table 4-3 : Transceiver SPI interface..............................................................................21
Table 4-4 nRF2401 subsystem main modes....................................................................22
Table 4-5 Table of configuration words. .........................................................................30
Table 4-6 Configuration data word.................................................................................32
Table 4-7 PLL setting. ...................................................................................................33
Table 4-8 Number of bits in payload. .............................................................................33
Table 4-9 Address of receiver 2 and receiver 1. .............................................................35
Table 4-10 Number of bits reserved for RX address + CRC setting. ...............................35
Table 4-11 RF operational settings. ................................................................................37
Table 4-12 Crystal frequency setting...............................................................................37
Table 4-13 RF output power setting. ..............................................................................39
Table 4-14 Frequency channel and RX / TX setting. .......................................................39
Table 4-15 Data package description.............................................................................41
Table 4-16 Operational timing for nRF2401 subsystem...................................................42
Table 5-1 : ADCCON register, SFR 0xA1, default initial data value is 0x80....................49
Table 5-2 : ADCSTATIC register, SFR 0xA4, default initial data value is 0x0A. .............49
Table 5-3 : ADC data SFR-registers, SFR 0xA2 and 0xA3............................................49
Table 6-1 : PWM control registers - SFR 0xA9 and 0xAA.............................................54
Table 7-1 : nRF24E1 interrupt sources...........................................................................55
Table 7-2 : IE Register – SFR 0xA8...............................................................................56
Table 7-3 : IP Register – SFR 0xB8...............................................................................56
Table 7-4 : EXIF Register – SFR 0x91 ..........................................................................57
Table 7-5 : EICON Register – SFR 0xD8 ......................................................................57
Table 7-6 : EIE Register – SFR 0xE8.............................................................................57
Table 7-7 : EIP Register – SFR 0xF8.............................................................................58
Table 7-8 : Interrupt Natural Vectors and Priorities.........................................................59
Table 7-9 : Interrupt Flags, Enables, and Priority Control................................................59
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Table 8-1 : TICK control register - SFR 0xB5 ...............................................................61
Table 8-2 : RTC and Watchdog SFR-registers ...............................................................64
Table 8-3 Reset control registe - SFR 0xB1. ..................................................................65
Table 9-1 : PCON Register – SFR 0x87........................................................................65
Table 9-2 : CK_CTRL register - SFR 0xB6..................................................................66
Table 9-3 : Startup times from Power down mode..........................................................67
Table 10-1 : EEPROM layout ........................................................................................69
Table 10-2 : Legend for Instruction Set Table .................................................................70
Table 10-3 : nRF24E1 Instruction Set, Arithmetic Instructions.........................................72
Table 10-4 : nRF24E1 Instruction Set, Logical Instructions.............................................73
Table 10-5 : nRF24E1 Instruction Set, Boolean Instructions............................................74
Table 10-6 : nRF24E1 Instruction Set, Data Transfer Instructions. ..................................75
Table 10-7 : nRF24E1 Instruction Set, Branching Instructions.........................................76
Table 10-8 : nRF24E1 Instruction Set, Miscellaneous Instructions...................................77
Table 10-9 : Special Function Registers summary...........................................................80
Table 10-10 : Special Function Register reset values and description, alphabetically. .......82
Table 10-11 : PSW Register – SFR 0xD0......................................................................82
Table 10-12 : SFR registers unique to nRF24E1.............................................................83
Table 10-13 : TMOD Register – SFR 0x89 ...................................................................85
Table 10-14 : TCON Register – SFR 0x88....................................................................85
Table 10-15 : CKCON Register – SFR 0x8E, ...............................................................88
Table 10-16 : T2CON Register – SFR 0xC8 .................................................................90
Table 10-17 : Timer 2 Mode Control Summary..............................................................90
Table 10-18 : Serial Port Modes ....................................................................................92
Table 10-19 : SCON Register – SFR 0x98....................................................................93
Table 10-20 : Timer 1 Reload Values for Serial Port Mode 1 Baud Rates.......................95
Table 10-21 : Timer 2 Reload Values for Serial Port Mode 1 Baud Rates.......................96
Table 11-1 : nRF24E1 Electrical specifications .............................................................103
Table 14-1 RF output power setting for the nRF24E1...................................................108
Table 14-2 Crystal specification of the nRF24E1..........................................................108
Table 15-1 Recommended components (BOM) in nRF24E1 with antenna matching
network ................................................................................................................111
Table 18-1 :Definitions .................................................................................................116
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PRODUCT SPECIFICATION
nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
18 DEFINITIONS
Data sheet status
Objective product specification
Preliminary product
specification
Product specification
This datasheet contains target specifications for product development.
This datasheet contains preliminary data; supplementary data may be
published from Nordic Semiconductor ASA later.
This datasheet contains final product specifications. Nordic Semiconductor
ASA reserves the right to make changes at any time without notice in order to
improve design and supply the best possible product.
Limiting values
Stress above one or more of the limiting values may cause permanent damage to the device. These are stress
ratings only and operation of the device at these or at any other conditions above those given in the
Specifications sections of the specification is not implied. Exposure to limiting values for extended periods may
affect device reliability.
Application information
Where application information is given, it is advisory and does not form part of the specification.
Table 18-1 :Definitions
Nordic Semiconductor ASA reserves the right to make changes without further notice to the
product to improve reliability, function or design. Nordic Semiconductor does not assume
any liability arising out of the application or use of any product or circuits described herein.
LIFE SUPPORT APPLICATIONS
These products are not designed for use in life support appliances, devices, or systems
where malfunction of these products can reasonably be expected to result in personal injury.
Nordic Semiconductor ASA customers using or selling these products for use in such
applications do so at their own risk and agree to fully indemnify Nordic Semiconductor
ASA for any damages resulting from such improper use or sale.
Product Specification: Revision Date: 10.06.2004.
Datasheet order code: 100604-nRF24E1.
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PRODUCT SPECIFICATION
nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
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PRODUCT SPECIFICATION
nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
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PRODUCT SPECIFICATION
nRF24E1 2.4 GHz Radio Transceiver with Microcontroller
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