Blinking an LED is the "Hello World" program of hardware. It is also one of the most popular Arduino program, and I bet electronics enthusiast has run it at least once in their life. In this blog post, I am going to show you Our solutions to blink an LED with Arduino so far relied on Arduino's built-in functions, so they would virtually work on any board supported by the Arduino environment. However, if we focus just on the Uno board, we can start taking advantage of its specific hardware features - namely, timers and interrupts. The two resistors, R1 and R2 are used to limit the Optocoupler LED current. TRIAC and the Driving Circuit: TRIAC is a bidirectional device that conducts current on both sides of the Terminals. The bidirectional feature of TRIACs is very useful for controlling alternating-current (AC) operated devices. ... Blynk.begin(auth, ssid, pass); dimmer.