#include <Wire.h>

int M3200address = 0x28;   // 0x28, 0x36 or 0x46, depending on the sensor.
float maxPressure =100;  // pressure in PSI for this sensor, 100, 250, 500, ... 10k.
byte status;

unsigned long pressureMillis = 0;
const int pressureTiming = 500; // 500ms every data acquisition

void setup (){
Serial.begin(9600);
Serial.println("M3200 initializing");
Wire.begin();
}

void loop(){
if (millis()-pressureMillis >= pressureTiming){
  pressureMillis = millis();
Wire.requestFrom(M3200address,4);   // request 4 bytes
int n = Wire.available();
  if( n == 4){
    status = 0;
    uint16_t rawP;     // pressure data from sensor
    uint16_t rawT;     // temperature data from sensor
    rawP = (uint16_t) Wire.read();    // upper 8 bits
    rawP <<= 8;
    rawP |= (uint16_t) Wire.read();    // lower 8 bits
    rawT = (uint16_t)  Wire.read();    // upper 8 bits
    rawT <<= 8;
    rawT |= (uint16_t) Wire.read();   // lower 8 bits

    status = rawP >> 14;   // The status is 0, 1, 2 or 3
    rawP &= 0x3FFF;   // keep 14 bits, remove status bits

    rawT >>= 5;     // the lowest 5 bits are not used
  
 // The math could be done with integers, but I choose float for now
    float pressure = ((rawP - 1000.0) / (15000.0 - 1000.0)) * maxPressure;
    float temperature = ((rawT - 512.0) / (1075.0 - 512.0)) * 55.0;

    Serial.print("Status = ");
    Serial.println(status);
    Serial.print( "Pressure = ");
    Serial.println( pressure);
    Serial.print( "Temperature = ");
    Serial.println( temperature);
    Serial.println("-------------------------------------");

  }else{
    Serial.println( "M3200 Pressure Transducer not Detected");
  }
}

}