Serial server for toggle pins hi/lo Arduino Leonardo

serial.cpp

static const int BLUE = 7;
static const int GREEN = 8;

void setup() {
  Serial.begin(115200);
  pinMode(BLUE, OUTPUT);
  pinMode(GREEN, OUTPUT);
  digitalWrite(BLUE, LOW);
  digitalWrite(GREEN, LOW);
}

bool cmd_valid(String cmd) {
  return (
    cmd.length() == 2 && 
    (cmd[0] == 'B' || cmd[0] == 'G') &&
    (cmd[1] == '0' || cmd[1] == '1')
  );
}

void loop() {
  if (Serial.available()) {
    String cmd = Serial.readStringUntil('\n');
    cmd.trim();
    if (cmd_valid(cmd)) {
      // Serial.printf("Got command: \"%s\"\n", cmd);
      int value = cmd[1] == '0' ? LOW : HIGH;
      int pin = cmd[0] == 'B' ? BLUE : GREEN;
      digitalWrite(pin, value);
    } else {
      // Serial.printf("Unsupported cmd: \"%s\". Ignoring...\n", cmd);
    }
  }
}