Arduino sketch converting PPM input to FMS-PIC serial data flying in a flight simulator with a remote control

sketch_flysky.ino

#include <PPMReader.h>

const byte ppmInputPin = 3;
const byte channels = 6;

const unsigned PPM_MIN = 1000;
const unsigned PPM_RANGE = 1000;
const unsigned FMS_MAX = 254;

PPMReader ppm(ppmInputPin, channels);

void setup() {
  Serial.begin(19200);
}

void loop() {
  // Start byte.
  Serial.write(255);
  for (byte channel = 1; channel <= channels; ++channel) {
      unsigned raw = ppm.latestValidChannelValue(channel, 0);
      outputValue(raw);
  }
  delay(50);
}

void outputValue(int raw) {
  unsigned long offset = max(0, raw - PPM_MIN);
  unsigned value = min(FMS_MAX, offset * FMS_MAX / PPM_RANGE);
  Serial.write(value);
}