Hi friends,

I need to improve some function of an working project. As I need more I/O
pins, my idea is to optimize the existing use.actually I have three LED, one
beeper and four pushbuttons.

My idea is to use the same pins for driving LEDS and listen pushbutton.

But the trouble that i think should be is the conflict that can exist if a
LED is lighted and the push button should be listen.

Using a sort of multiplexing, that for ten millisecond drive a LED and for
the following ten millisecon listen the pushbutton going to ground, should
be a good approach, but what happens at the PIC internal circuit, if the pin
is pushed to ground when it drive the LED?

Before to fried a PIC, I would like to have your opinion about this
approach.

If I use a 470 Ohm limiting current resistor to drive LED and in parallel to
the LED I connect the pushbutton  there are any risk??

I understand that when the pushbutton is pressed the LED will go off,ant
this is acceptable, but is sufficient 470 Ohm to save the driving circuit?

Thanks

Regards

Leo

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