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nrf24le1 Wiring Library

A Wiring-like wrapper to use the nrf24le1 SoC

Go to https://hackaday.io/project/5794-nrf24le1-wiring-library for more details

Usage

pinMode, digitalRead, digitalWrite, analogRead, analogWrite

pinMode(P0_0, INPUT | PULLUP);

digitalRead(P0_0);

digitalWrite(P0_0, HIGH);

pinMode is slightly different in that you | together the options which are:

  • PULLUP
  • PULLDOWN
  • INPUT
  • OUTPUT
  • HIGH_POWER
  • NORMAL_POWER

digitalRead, digitalWrite, analogWrite work as usual.

noPullup() and pullup() are absent and rolled into pinMode()

Analog and PWM Functions

ADC is setup in 12 bit resolution, PWM pre-scaler to 10 and width to 8 bits.

Interrupts

interrupts(), noInterrupts(), detachInterrupt() work as expected.

attachInterrupt(GP_INT, condition) is slightly different in that there is no function argument, conditions are LOW and FALLING. You need to write an ISR for INTERRUPT_VECTOR_IFP. Depending on your chip, the GPINT options are

  • INTERRUPT_IFP_INPUT_GPINT0 //P0.0 on 24-pin, P0.5 on 32-pin, P1.2 on 48-pin
  • INTERRUPT_IFP_INPUT_GPINT1 //P0.2 on 24-pin, P0.6 on 32-pin, P1.3 on 48-pin
  • INTERRUPT_IFP_INPUT_GPINT2 //Not present on 24-pin or 32-pin, P1.4 on 48-pin

You can define an ISR like

ISR(INTERRUPT_VECTOR_IFP){
  //do something
}

The list of vectors:

  • INTERRUPT_VECTOR_IFP
  • INTERRUPT_VECTOR_T0
  • INTERRUPT_VECTOR_PWR_FAIL
  • INTERRUPT_VECTOR_T1
  • INTERRUPT_VECTOR_UART
  • INTERRUPT_VECTOR_T2
  • INTERRUPT_VECTOR_RFRDY
  • INTERRUPT_VECTOR_RFIRQ
  • INTERRUPT_VECTOR_SPI_2WIRE
  • INTERRUPT_VECTOR_WU_ON_PIN
  • INTERRUPT_VECTOR_XOSC_ADC_RNG
  • INTERRUPT_VECTOR_RTC2

Timing

millis() is implemented using timer0. Due to it's use of system resources, it is not started automatically. millisBegin() will start it. Thanks to maksms' GitHub repo for this routine. Access it through millis() which is a uint32_t.

delay() and delayMilliseconds() work as expected

Serial

serialBegin() sets up up at 38400 8n1 which is the maximum speed.

serialPrint and serialPrintLn are implemented as wrappers to printf_small(format, args)

serialPrint("wiring wrapper version %u", 1);

debugPrint(format, args) and debugPrintLn(format, args) are macros that wrap printf_small() and is enabled if DEBUG is defined:

debugPrint("nrf24le1 with no args", 0); debugPrint("nrf24le1 version %u", 1);

format output type argument-type
%d decimal int
%ld decimal long
%hd decimal char
%x hexadecimal int
%lx hexadecimal long
%hx hexadecimal char
%o octal int
%lo octal long
%ho octal char
%c character char
%s character generic pointer
%f float float*

SDCC is not compiled by default with float support

I2C

Automatically set up in master mode at 400kHz. I would like this to be made more Wiring-like.

wireWrite8(slave address, data) returns W2_NACK_VAL or W2_ACK_VAL

wireRead8(slave address, address) returns W2_NACK_VAL or W2_ACK_VAL

wireRead16(slave address, address) returns W2_NACK_VAL or W2_ACK_VAL

Watchdog

watchdogRun(millis) will start the watchdog and cause a reset if not called before millis runs out. Does not work in deep sleep mode. Minimum is 7.8125 ms, max is 512 seconds.

Sleep Modes

sleep(mode) will enter the passed mode. Modes are:

  • ACTIVE
  • STANDBY
  • REGISTER_RET
  • MEMORY_TIMER_ON
  • MEMORY_TIMER_OFF
  • DEEP_SLEEP

Random Number Generator

The nrf24le1 has an onboad RNG. The cstd random() has been replaced by the board RNG and returns a random byte.

Pins

Are defined as P0_0 P1_1etc.

gpio.h has defines for all three variants and also the special names for the pins which can be used as well.

AES Accelerator

The chip includes a hardware galois multiplication function.

uint8_t aesGaloisMultiply(uint8_t value1, uint8_t value2)