The loop usually waits for input from ... The main Arduino header file is named Arduino.h, as we saw above. You can hold down the Command key on your Mac keyboard and double-click any #define ...

void loop() { digitalWrite(PIN_LED,HIGH); delay(500); digitalWrite(PIN_LED,LOW); delay(500); } Now, let's compile and upload it to the Arduino UNO. Use the board set of commands to search for the ...