which led in the arduino uno microcontroller blinks when it transmits data?
On the Arduino Uno , there isn't a dedicated LED that blinks specifically for data transmission (like serial communication). However, there is one that blinks for data reception , and the confusion is very common. Let me clarify which LEDs do what: The LEDs on Arduino Uno 1. TX LED (Transmit) - This is the main answer Location: Labeled "TX" near digital pin 1 (D1) What it does: This LED blinks when the Arduino Uno transmits data to the computer via USB serial. When you'll see it blink: When your code uses Serial.print() or Serial.println() to send data to the Serial Monitor. 2. RX LED (Receive) Location: Labeled "RX" near digital pin 0 (D0) What it does: This LED blinks when the Arduino Uno receives data from the computer. When you'll see it blink: When you send commands from the Serial Monitor to your Arduino . 3. Built-in LED (Pin 13) Location: ...