void setup() { Serial.begin(31250); pinMode(13, OUTPUT); } void loop() { byte buf[3]; buf[0] = 0x90; // Note on buf[1] = 60; // C buf[2] = 127; // max volume Serial.write(buf, 3); digitalWrite(13, LOW); delay(500); buf[0] = 0x80; // Note off buf[1] = 60; // C buf[2] = 0; Serial.write(buf, 3); digitalWrite(13, HIGH); delay(500); }