#include <RF24.h>
#include <nRF24L01.h>

//tally LEDs
const int tallyLED[] = {2,4};
const int tallyLEDlength = 2;
boolean tallyLEDstat[2];

# define errorLED 6

//init NRF
RF24 radio (7, 8);
const uint16_t address = 0xADB5;
uint16_t datareceive;

//define min interval to show error
unsigned long currentTime = millis();
unsigned long previousTime = 0;
const long errorTime = 3000;

void setup(){
   for (int i=0; i < tallyLEDlength; i++){
    pinMode(tallyLED[i], OUTPUT);
    digitalWrite(tallyLED[i], LOW);
  }
  pinMode(errorLED, OUTPUT);
  digitalWrite(errorLED, HIGH);

  pinMode(3, OUTPUT);
  digitalWrite(3, LOW);

  pinMode(5, OUTPUT);
  digitalWrite(5, LOW);

  //start Serial
  Serial.begin(9600);
  Serial.println("start serial");

  //start NRF
  Serial.println("start NRF");
  radio.begin();
  radio.openReadingPipe(0, address);
  radio.setPALevel(RF24_PA_HIGH);
  radio.setDataRate(RF24_1MBPS);
  radio.setAutoAck(false);
  radio.disableCRC();
  radio.startListening();

  delay(20);
}

void loop(){
  while (!updateLoop());
  radio.read(&datareceive, sizeof(datareceive));
  Serial.print("data: ");
  Serial.println(datareceive, BIN);
  if (getChecksum((datareceive >> 8) & 0xFF) != (datareceive & 0xFF)){
    Serial.println("corrupted data");
    digitalWrite(errorLED, HIGH);
  }else digitalWrite(errorLED, LOW);
  for (int i=0; i < tallyLEDlength; i++){
    digitalWrite(tallyLED[i], (datareceive >> 15 - i) & 1);
  }
}

boolean updateLoop(){
  currentTime = millis();
  if (radio.available()){
    Serial.println("new package");
    previousTime = currentTime;
    return true;
  }
  else if (currentTime - previousTime >= errorTime){
    Serial.println("timeout");
    digitalWrite(errorLED, HIGH);
  }
  return false;
}

byte getChecksum(byte data){
  byte checksum = 0;
  for (int i=8; i<8; i++) checksum += (data >> i) & 1;
  return checksum;
}