SAMDblink.ino

const int RX_LED = PIN_LED_RXL; // RX LED on pin 25, we use the predefined PIN_LED_RXL to make sure
const int TX_LED = PIN_LED_TXL; // TX LED on pin 26, we use the predefined PIN_LED_TXL to make sure
bool ledState = LOW;
void setup() {
  pinMode(RX_LED, OUTPUT);  pinMode(TX_LED, OUTPUT);
  digitalWrite(RX_LED, HIGH);  digitalWrite(TX_LED, HIGH);
}
void loop() {
  // Toggle RX and TX LED's
  ledState = !ledState;
  digitalWrite(RX_LED, ledState);
  digitalWrite(TX_LED, !ledState);
  delay(500);
}