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Topic: Can you use txd and rxd as digital input/outputs (Read 3705 times) previous topic - next topic


Apr 29, 2012, 06:01 pm Last Edit: Apr 29, 2012, 06:05 pm by jonisonvespa Reason: 1
just wondering if you can use pins, 2,3 (txd, and rxd) as input/outputs or are they simply used for transmitting/recieving data? im sure thay are just want to be sure, they are marked up as IO1 and Io2 on the circuit diagram.

thank you

Jack Christensen

They can operate as GPIO pins as well as serial I/O, just not at the same time :)


yes, but you prob mean pin 0 and 1 ?

but you cannot use them when you also use them as serial.

you can also use 1 pin e.g. serial out for serial (e.g. msg to PC) and the other as a digital IO .
Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)


ok thanks for the info just wanted to be sure.

Nick Gammon

Be aware that there is a pull-up from the USB driver chip, through the 1K resistors connecting pins 0 and 1 to it. If you try to use them as inputs (particularly Rx I think) there will be a voltage on it/them.
Please post technical questions on the forum, not by personal message. Thanks!

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