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Author Topic: can we use RX & TX as gerneral purpose I/O  (Read 633 times)
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Hi,
   I am usinag Ardunio Duemilanove board. I am trying to set TX & RX pins as input pins. But, if i measure the voltage at RX & TX pins it shows 4.5V always. And if i measure voltage at other pins which shows me 200mV ( This pins also set to input mode). How can use RX & TX as a general purpose I/O.
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Yes you can but it has the output of the serial / USB chip connected to it through a 1K so any input must override that. Plus you have to disconnect it when uploading.
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Hi,
    Even i have disconnected the usb and i am powering the unit using external power supply. Then also i am getting 4.5v at both TX  & RX pins.all other pins gives me 0v or 250mv. Weather i need to do anything on the 1K resistor or any other options.
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It's time you posted your code I think.
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Then also i am getting 4.5v at both TX  & RX pins.all other pins gives me 0v or 250mv.
Yes you will. The USB / Serial chip is still on the board and is still being powered.

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Weather i need to do anything on the 1K resistor or any other options.
You need to connect it to an input that will drive a 1K pull up load to low for using it as an input.
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And if i measure voltage at other pins which shows me 200mV ( This pins also set to input mode). How can use RX & TX as a general purpose I/O.

I/O is Input/Output.

Did you have Input in mind, or Output?
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TX & RX  as a input pin.
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TX & RX  as a input pin.

In that case Reply #1 gives you your answer.
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