Hello.
I am wanting to send an infrared signal from my nrf52 DK (pca10040). I've found code online for sending custom IR signals using pwm and a gpio pin. The IR signals are 38kHz and I am wondering if that will work on the nrf52 DK.
#define txPinIR 11 //ASSIGN A DIFFERENT PIN HERE WHEN READY FOR TESTING
unsigned char carrierFreq = 38;
unsigned char period = (1000 + carrierFreq / 2) / carrierFreq;
unsigned char periodHigh = (period + 1) / 3;
unsigned char periodLow = period - periodHigh;
unsigned long sigTime = 0; //used in mark & space functions to keep track of time
unsigned long sigStart = 0; //used to calculate correct length of existing signal, to handle some repeats
#define NEC_HEX_VALUE 0xAAAAAAAAUL //UL makes this an unsigned long
#define NEC_BIT_COUNT 32
void sendHexNEC(unsigned long sigCode, byte numBits, unsigned char repeats, unsigned char kHz) {
/* A basic 32 bit NEC signal is made up of:
* 1 x 9000 uSec Header Mark, followed by
* 1 x 4500 uSec Header Space, followed by
* 32 x bits uSec ( 1- bit 560 uSec Mark followed by 1690 uSec space; 0 - bit 560 uSec Mark follwed by 560 uSec Space)
* 1 x 560 uSec Trailer Mark
* There can also be a generic repeat signal, which is usually not neccessary & can be replaced by sending multiple signals
*/
#define NEC_HEADER_MARK 9000
#define NEC_HEADER_SPACE 4500
#define NEC_ONE_MARK 560
#define NEC_ZERO_MARK 560
#define NEC_ONE_SPACE 1690
#define NEC_ZERO_SPACE 560
#define NEC_TRAILER_MARK 560
unsigned long bitMask = (unsigned long) 1 << (numBits - 1); //allows for signal from 1 bit up to 32 bits
//
//if (carrierFreq != kHz) initSoftPWM(kHz); //we only need to re-initialise if it has changed from last signal sent
sigTime = micros(); //keeps rolling track of signal time to avoid impact of loop & code execution delays
sigStart = sigTime; //remember for calculating first repeat gap (space), must end 108ms after signal starts
// First send header Mark & Space
mark(NEC_HEADER_MARK);
space(NEC_HEADER_SPACE);
while (bitMask) {
if (bitMask & sigCode) { //its a One bit
mark(NEC_ONE_MARK);
space(NEC_ONE_SPACE);
}
else { // its a Zero bit
mark(NEC_ZERO_MARK);
space(NEC_ZERO_SPACE);
}
bitMask = (unsigned long) bitMask >> 1; // shift the mask bit along until it reaches zero & we exit the while loop
}
// Last send NEC Trailer MArk
mark(NEC_TRAILER_MARK);
//now send the requested number of NEC repeat signals. Repeats can be useful for certain functions like Vol+, Vol- etc
/* A repeat signal consists of
* A space which ends 108ms after the start of the last signal in this sequence
* 1 x 9000 uSec Repeat Header Mark, followed by
* 1 x 2250 uSec Repeat Header Space, followed by
* 32 x bits uSec ( 1- bit 560 uSec Mark followed by 1690 uSec space; 0 - bit 560 uSec Mark follwed by 560 uSec Space)
* 1 x 560 uSec repeat Trailer Mark
*/
//First calcualte length of space for first repeat
//by getting length of signal to date and subtracting from 108ms
if (repeats == 0) return; //finished - no repeats
else if (repeats > 0) { //first repeat must start 108ms after first signal
space(108000 - (sigTime - sigStart)); //first repeat Header should start 108ms after first signal
mark(NEC_HEADER_MARK);
space(NEC_HEADER_SPACE / 2); //half the length for repeats
mark(NEC_TRAILER_MARK);
}
while (--repeats > 0) { //now send any remaining repeats
space(108000 - NEC_HEADER_MARK - NEC_HEADER_SPACE / 2 - NEC_TRAILER_MARK); //subsequent repeat Header must start 108ms after previous repeat signal
mark(NEC_HEADER_MARK);
space(NEC_HEADER_SPACE / 2); //half the length for repeats
mark(NEC_TRAILER_MARK);
}
}
void mark(unsigned int mLen)
{
sigTime += mLen;
unsigned long now = micros();
unsigned long dur = sigTime - now;
if (dur == 0) return;
while ((micros() - now) < dur)
{
digitalWrite(txPinIR, HIGH);
if (periodHigh) delayMicroseconds(periodHigh);
digitalWrite(txPinIR, LOW);
if (periodLow) delayMicroseconds(periodLow);
}
}
void space(unsigned long sLen)
{
sigTime += sLen;
unsigned long now = micros();
unsigned long dur = sigTime - now;
if (dur == 0) return;
while ((micros() - now) < dur) ;
}
void setup()
{
Serial.begin(9600);
//while(!Serial);
delay(500);
Serial.println(period);
Serial.println(periodHigh);
Serial.println(periodLow);
pinMode(txPinIR, OUTPUT);
periodHigh -= 3;
periodLow -= 7;
}
void loop()
{
Serial.println(F("Sending NEC_HEX_VALUE @ 38kHz"));
sendHexNEC(NEC_HEX_VALUE, NEC_BIT_COUNT, 0, 38);
delay(5000); //wait 5 seconds between each signal (change to suit)
}
This is my code that is based on AnalysIR's forum on sending IR pwm. This code works well with my two arduino unos; I can send custom hex code signals and receive them on my other Arduino.
I use bsp from adafruit to upload the code from Arduino IDE to my dk but I've only gotten it to send a couple of signals that did not match the one I was intending to send. Most of the time it does not even send a signal out.
Do I have to configure a pwm setting in the nrf52 dk or use a different pin? I assume sending 38kHz signals is not the problem so I would like to know if there is something I am missing that is specific to this board.
Thank you.
