Receiver

Receiver.ino

#include <SPI.h>
#include <Wire.h>
#include <RF24.h>


// https://quadmeup.com/generate-ppm-signal-with-arduino/
#define CHANNEL_NUMBER 1  //set the number of channels
#define CHANNEL_DEFAULT_VALUE 1000  //set the default servo value
#define FRAME_LENGTH 22500  //set the PPM frame length in microseconds (1ms = 1000µs)
#define PULSE_LENGTH 300  //set the pulse length
#define ON_STATE 0  //set polarity of the pulses: 1 is positive, 0 is negative
#define SIGNAL_PIN 10  //set PPM signal output pin on the arduino

#define CE_PIN 7
#define CSN_PIN 8

#define SENDER_MIN_VALUE 0
#define SENDER_MAX_VALUE 1023

#define MOTOR_MIN_VALUE 1500
#define MOTOR_MAX_VALUE 2250

#define MAGIC_STORAGE_ADDRESS 0xE8E8F0F0E1LL

/*this array holds the servo values for the ppm signal
  change theese values in your code (usually servo values move between 1000 and 2000)*/
int ppm[CHANNEL_NUMBER] = {CHANNEL_DEFAULT_VALUE};


RF24 radio(CE_PIN, CSN_PIN);

const uint64_t pipe = MAGIC_STORAGE_ADDRESS;

int message;
long mappedValue = 0;

void setup() {
  Serial.begin(57600);

  pinMode(SIGNAL_PIN, OUTPUT);
  digitalWrite(SIGNAL_PIN, !ON_STATE);  //set the PPM signal pin to the default state (off)

  // C+P
  cli();
  TCCR1A = 0; // set entire TCCR1 register to 0
  TCCR1B = 0;

  OCR1A = 100;  // compare match register, change this
  TCCR1B |= (1 << WGM12);  // turn on CTC mode
  TCCR1B |= (1 << CS11);  // 8 prescaler: 0,5 microseconds at 16mhz
  TIMSK1 |= (1 << OCIE1A); // enable timer compare interrupt
  sei();

  // Setup RECEIVER
  radio.begin();
  radio.openReadingPipe(1, pipe);
  radio.startListening();
}

void loop() {
  if (radio.available()) {
    radio.read(&message, sizeof(message));


    // SET PPM
    mappedValue = map(message, SENDER_MIN_VALUE, SENDER_MAX_VALUE, MOTOR_MIN_VALUE, MOTOR_MAX_VALUE);
    ppm[0] = (int) mappedValue;

    Serial.print("Message received: ");
    Serial.println(message);

    Serial.print("Value sent to ppm: ");
    Serial.println((int) mappedValue);
    delay(10);
  } else {
    Serial.println("Radio is dead.");
  }
}

// C+P
ISR(TIMER1_COMPA_vect) {
  static boolean state = true;

  TCNT1 = 0;

  if (state) {  //start pulse
    digitalWrite(SIGNAL_PIN, ON_STATE);
    OCR1A = PULSE_LENGTH * 2;
    state = false;
  } else { //end pulse and calculate when to start the next pulse
    static byte cur_chan_numb;
    static unsigned int calc_rest;

    digitalWrite(SIGNAL_PIN, !ON_STATE);
    state = true;

    if (cur_chan_numb >= CHANNEL_NUMBER) {
      cur_chan_numb = 0;
      calc_rest = calc_rest + PULSE_LENGTH;//
      OCR1A = (FRAME_LENGTH - calc_rest) * 2;
      calc_rest = 0;
    }
    else {
      OCR1A = (ppm[cur_chan_numb] - PULSE_LENGTH) * 2;
      calc_rest = calc_rest + ppm[cur_chan_numb];
      cur_chan_numb++;
    }
  }
}