#include <HardwareSerial.h>
HardwareSerial SerialPort(2); // use UART2
void setup()
{
    SerialPort.begin(15200, SERIAL_8N1, 16, 17);
}
void loop()
{
    SerialPort.print(1);
    delay(5000);
    SerialPort.print(0);
    delay(5000);
}