// Share and enjoy!

#include <SPI.h>
#include "nRF24L01.h"
#include "RF24.h"
#include <Adafruit_NeoPixel.h>

#define PIXEL_PIN 6U
#define NUMPIXELS 16U

Adafruit_NeoPixel pixels = 
  Adafruit_NeoPixel(NUMPIXELS, PIXEL_PIN, NEO_GRB + NEO_KHZ800);

// The Micro:bit's transmission channel
#define CH 2U

// Set up nRF24L01 radio on SPI bus plus pins 7 & 8
RF24 radio(7,8);

uint8_t n, num = 0;
uint8_t currCarr, lastCarr = 0;
uint8_t sampleCount = 0;
uint8_t currBit = 0;
uint8_t incomingByte = 0;

//=========================================================
void setup(void) {

  Serial.begin(115200);
  radio.begin();
  radio.setAutoAck(false);  
  //radio.setPALevel(RF24_PA_HIGH);
  radio.setChannel(CH);

  pixels.begin();
  
}

//=========================================================
bool carrierPresent(void) {
  
  radio.startListening();
  delayMicroseconds(100);
  radio.stopListening();
  return radio.testCarrier();
  
}

//=========================================================
void displayAngle(const uint8_t raw) {

  uint8_t pStart, pStop, i;
  uint8_t rawPerPixel = 256 / (NUMPIXELS / 2);
  uint8_t midVal;

  for (i = 0; i <= NUMPIXELS; ++i) {
    pixels.setPixelColor(i, 0, 0, 32);
  }
  
  pStart = raw / rawPerPixel + 1;
  pStop = pStart + (NUMPIXELS / 2) - 2;

  for (i = pStart; i <= pStop; ++i) {
    pixels.setPixelColor(i, 32, 0, 0);
  }

  midVal = pStart * rawPerPixel - raw;
  pixels.setPixelColor(pStart - 1, midVal, 0, 32 - midVal);
  pixels.setPixelColor(pStop + 1, 32 - midVal, 0, midVal);

  pixels.show();
  
}

//=========================================================
void loop(void) {
      
      currCarr = carrierPresent();

      // Did we spot a change?
      if (currCarr != lastCarr) {

        // Is it the end of a data bit?
        if (currCarr) {

          // We ignore the first "bit" because it was just the "Start" signal
          if (!currBit) {
            currBit = 1;          
          } else {

              // A Legit Bit!
              incomingByte <<= 1;
              if (sampleCount >= 10) {
                  incomingByte += 1;
              }

              ++currBit;
              if (currBit == 9) {
              
                  currBit = 0;
                  Serial.println(incomingByte);
                  displayAngle(incomingByte);  
                  incomingByte = 0;
              
              }
              
            } // else
          
        }
        
        sampleCount = 0;
        lastCarr = currCarr;

      } else {
          
          ++sampleCount;
          if (sampleCount > 50) {
            currBit = 0;
            incomingByte = 0;
          } 
          
        }

}