I have an Arduino Uno. I am building a custom shield and was wondering how I would connect two of the LEDs on the shield to the TX / RX LEDs on the Uno. Digital pins 0 and 1 seem obvious, but after further research, it appears that they are not for this.

In better terms, I want two LEDs on my shield that replicate the TX / Rx LEDs on the Arduino Uno.

How would I do this?

2 Answers 2


The TX/RX LEDs on the Uno are not connected to the main MCU but are instead connected to the USB communication chip, be it a FTDI or ATmega16U2. You would need to solder wires to the appropriate connections on the board and then connect them to the shield in question.


If you need just indicate data on TX/RX you can make simple circuit on shield bound to TX/RX lines.

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