/**
Author: tiger888
Date: 21/08/2024
Last Update: Initial Version 1.0
Sydney, Australia
******* THE PROJECT *********************************
Simulation: NRF24L01 RF Transceiver (RECEIVER Only)
*****************************************************
Project Components;
1 x Arduino Nano
1 x 5v Power supply but pin to Arduino 3.3v. 
        Optional use mobile phone power bank instead.  
1 x NRF24L01 (RF Transceiver) - Receiver mode only
1 x Capacitors 470 micro farad (white noise filter)
1 x Resistors 220 ohm (LED current limiter)
1 x LED yellow (Rx status indicator: steady ON when received TX, else OFF)
1 x LED red (Rx status indicator: steady ON when no data received, else OFF)
1 x LED blue (Rx is on standby)
1 x LED green (mobile phone power bank battery, ON is charged, OFF is no charge)
Note 1: we used Arduino 5v to monitor the mobile phone pwoer bank status
Note 2: In the case that red & yellow LEDs are ON, Rx received data but data is empty (issue?)
*/

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

// Pin 7, 8 are CE & CSN NFR24L01 default pin config
#define CE_PIN  7
#define CSN_PIN 8
// Monitor LED Rx status
#define LED_RX_PIN 5  // yellow (steady ON when Rx receives data, else OFF)
#define LED_NODATA_PIN 2  // red (Normally OFF, Steady ON when no data received)
#define LED_STANDBY_PIN 6 // blue Rx is on Standby

// RF24 simple constructor
RF24 radio(CE_PIN, CSN_PIN);

// Import: this defined address MUST match its Transmitter pair
const byte thisSlaveAddress[5] = {'R','x','A','A','A'};
char dataReceived[32] = {0};
char testData[32] = {"Hello World testing..."};

void setup() {

  Serial.begin(9600);
  Serial.flush();
  
  // Default LED Rx status
  pinMode(LED_RX_PIN, OUTPUT);
  digitalWrite(LED_RX_PIN, LOW);
  pinMode(LED_NODATA_PIN, OUTPUT);
  digitalWrite(LED_NODATA_PIN, LOW);
  pinMode(LED_STANDBY_PIN, OUTPUT);
  digitalWrite(LED_STANDBY_PIN, LOW);
  
  // Init RF24 as receiver mode 
  radio.begin();
  radio.setDataRate(RF24_250KBPS);
  radio.openReadingPipe(1, thisSlaveAddress);
  radio.startListening();
  
  Serial.println("Receiver setup completed.");
}

void loop(){

  // defualt Rx Standby to OFF
  digitalWrite(LED_STANDBY_PIN, LOW);     // blue LED OFF

  boolean rxStatus  = radio.available();
  //---------- debug only - done remove it --------------------
  rxStatus = true; // check the blue LED (Rx is on standby)
  //-----------------------------------------------------------

  if (rxStatus){
    
    radio.read(&dataReceived, sizeof(dataReceived));
    
    // Testing only - remove when done
    strcpy(dataReceived, testData);
    //////////////////////////////////   

    // Check if dataReceived is empty
    if (strlen(dataReceived) == 0) {
      // Rx received but data is empty
      digitalWrite(LED_RX_PIN, HIGH);      // Yellow LED ON
      flashingLed(LED_NODATA_PIN, 500); // Red LED flashing
      Serial.println("Data received but data is empty");
    } else {
      // Rx received data that is not empty (all good here.)
      digitalWrite(LED_RX_PIN, HIGH);      // Yellow LED ON
      // flashing yellow LED and Buzzer : we have received Tx meesage 
      flashingLed(LED_RX_PIN, 500);
      digitalWrite(LED_NODATA_PIN, LOW);   // Red LED OFF
      Serial.print("Data received: ");
      Serial.println(dataReceived);
    }

  } else {
    // radio is available but no trasmission ON
    digitalWrite(LED_STANDBY_PIN, HIGH);     // blue LED ON standby
    Serial.println("Receiver is on standby.");
  } 
}

void flashingLed(int ledPinNbr, int delayTime){

  digitalWrite(ledPinNbr, HIGH);
  delay(delayTime);
  digitalWrite(ledPinNbr, LOW);
  delay(delayTime);
}