pmstest.ino

#define _DEBUG

unsigned int pm1 = 0;
unsigned int pm2_5 = 0;
unsigned int pm10 = 0;
long lastPmReading = 0;

byte buffer[24];

void setup() {
  Serial.begin(9600);
  Serial.println("Hello!");
  Serial1.begin(9600);
}

unsigned int packetIndex = 0;
void offer(byte value) {
  buffer[packetIndex] = value;
  if (packetIndex == 0) {
    if(value == 0x42) {
      packetIndex = 1;
    }
    return;
  }

  if (packetIndex == 1) {
    if (value == 0x4d) {
      packetIndex = 2;
      return;
    } else {
      packetIndex = 0;
      return;
    }
  }

  if (packetIndex == 23) {
    measure();
    packetIndex = 0;
  } else {
    packetIndex ++;
  }
}


void measure() {
  for (unsigned int i = 0; i < sizeof(buffer); i++) {
    Serial.printf("%x ", buffer[i]);
  }
  Serial.println("");

  pm1 = 256 * buffer[4] + buffer[5];
  pm2_5 = 256 * buffer[6] + buffer[7];
  pm10 = 256 * buffer[8] + buffer[9];
}

void loop() {
  if (Serial1.available())
    offer(Serial1.read());
}