#include <SPI.h>

/* 

ARDUINO ports definitions - GPIOS and ADCs 

*/

#define RESET 8         //LDR  
#define MUX   2         //LDR  
#define PROG_MODE A2
#define BLUE A0
#define GREEN A1
#define MMC_CS 10
#define RTX_CS 9
#define POWER 6
#define SELECT_MODE_1 7
#define SELECT_MODE_2 3

#define SHT21_ADDRESS        0x40    // Direction of the sht21  

unsigned long t = 0;
byte seq_byte = 0;

void setup() {
  pinMode(RESET, OUTPUT);
  digitalWrite(RESET, LOW); //RESET ON
  delay(100);
  digitalWrite(RESET, HIGH); //RESET OFF
  pinMode(MUX, OUTPUT);
  digitalWrite(MUX, LOW); //NORMAL MODE
  pinMode(PROG_MODE, OUTPUT);
  digitalWrite(PROG_MODE, LOW); //PROG_MODE OFF
  pinMode(GREEN, OUTPUT);
  digitalWrite(GREEN, HIGH); //GREEN ON
  pinMode(MMC_CS, OUTPUT);
  pinMode(52, OUTPUT);
  digitalWrite(MMC_CS, HIGH); //SPI MMC NO SELECT
  pinMode(RTX_CS, OUTPUT);
  digitalWrite(RTX_CS, HIGH); //SPI RTX NO SELECT
  pinMode(POWER, OUTPUT);
  digitalWrite(POWER, HIGH); //ENABLE POWER RTX
  SPI.begin();
  Serial.begin(9600);
  Serial1.begin(9600);
}

void loop() {
    if (millis() > (t + 3000)) {
    //Test SPI (Arduino=Master)

    digitalWrite(RTX_CS, HIGH); //Hay que ponerlo ya que SPI.begin no lo baja
    SPI.beginTransaction(SPISettings(1000000, LSBFIRST, SPI_MODE0));

    if (seq_byte == 254) {
      seq_byte == 0;
    } else {
      seq_byte ++;
    }
    Serial.println("Datos a enviar:");
    Serial.print("->P1: "); Serial.println(seq_byte);
    Serial.print("->P2: "); Serial.println(123);
    Serial.print("->P3: "); Serial.println(100);

    byte p1 = SPI.transfer(seq_byte);
    byte p2 = SPI.transfer(123);
    byte p3 = SPI.transfer(100);

    Serial.println("Datos recibidos:");
    Serial.print("<-P1: "); Serial.println(p1);
    Serial.print("<-P2: "); Serial.println(p2);
    Serial.print("<-P3: "); Serial.println(p3);
    SPI.endTransaction();

    digitalWrite(RTX_CS, LOW);
    t = millis();
  }

}