decode dsm packet

dsm.ino

#define BUFFER_SIZE  14
#define MAX_CHANS    8


int ledPin = 13;
int count = 0;
int chan[MAX_CHANS];
bool state = false;
bool sync = false;
byte  chanBuffer[BUFFER_SIZE];
uint8_t  chanPos;


void setup() {
  // initialize both serial ports:
  Serial.begin(115200);
  pinMode(ledPin, OUTPUT);
}
int decode(uint16_t dsm) {
  dsm &= 0x7ff;
  return ((((int)dsm - 1024) * 1000) / 1700) + 1500;
}

void loop() {
  // put your main code here, to run repeatedly:
  while (Serial.available() && (chanPos < BUFFER_SIZE)) {
    byte bt = Serial.read();
    if (bt == 0xAB && !sync && chanPos == 0) {
      sync = true;
      //Serial.println("start of sync msg");
    }
    if (sync) {
      chanBuffer[chanPos++] = bt;
      digitalWrite(ledPin, state = !state);
    }
  }
  if (chanPos == BUFFER_SIZE) {
    for (int i = 0; i < MAX_CHANS; ++i) {


      uint8_t spekChannel = i * 2;
      byte bh = chanBuffer[spekChannel];
      byte bl = chanBuffer[spekChannel + 1];


      // chan[spekChannel] = decode(bh | bl);
      chan[spekChannel] = bl;

    }

    for (int i = 0; i < MAX_CHANS; ++i) {
      Serial.print(" ");
      Serial.print(i);
      Serial.print(":");
      Serial.print(chan[i]);

    }
    Serial.println();

    //Serial.println("end of sync msg");
    sync = false;
    chanPos = 0;

  }
}