I am creating an IC checker for a large chunk of the 74ls series (basic TTL logic chips), which means that I have 14 pins running to the IC to verify its functionality. One pin is power (+5V) and another ground (GND), which are both consistently in the same seven and fourteen pin positions respectively, but the remaining 12 are various inputs and outputs that vary depending on the IC type.

With that stated, will there be any consequences to dynamically reconfiguring a pin from input to output -- or vice versa -- as different IC types are selected? Weird behavior or electrical failure? What if the IC remains plugged in while the the pins reconfigure? What if said IC is powered on and providing power to a pin as it reconfigures?

If you were curious, I am using a joystick and LCD display as an interface to selecting the appropriate IC to check.

1 Answer 1


There's no problem reconfiguring pins. It happens all the time. One example is with ping sensors where the pin is used as an output to send the ping and then switched to an input to wait for the response. The only caveat is that you must be sure what you're connected to. For instance, if you set a pin to OUTPUT and LOW and it just happens to be connected to a HIGH OUTPUT then you just fried your board.

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