For some reason today while using the OpenBench one of the input stop working :( There is anything I can do to understand if the problem is from the buffer or the FPGA? I wasn't doing anything fancy only read the value of a micro-controller io port.
It sounds to me that you likly damaged the input either by overvoltage or ESD or some other similat mechanism.
The easiest way to test if it is a problem with the buffer or the FPGA is to measure with a multimeter when you apply both 0 and 3.3v (or 5v).
Apply +3.3v (or +5v) to the input of the buffer (as you normally would use the board) then with a multimeter with a fine-pointed set of probes (you can use a needle, or a safety pin or something similar attached to the usual blunt probes you get with a multimeter) probe the corresponding output pin on the buffer and ensure you see 3.3v. If you do not see 3.3v then it is probably the buffer .
Repeat that procedure but instead apply 0v to the buffer input. You shouked expect to seer approximately 0v at the output as well. If this is not the case its likely the buffer.
If the test above passes, and you can see the input signal you apply to the output of the buffer, its likely a problem with the gpio pin on the FPGA.
If its a problem with the bugger you can buy a new one from digikey: https://www.digikey.ca/product-detail/e ... ND/1480284 (https://www.digikey.ca/product-detail/en/on-semiconductor/MC74LCX16245DTG/MC74LCX16245DTGOS-ND/1480284)
Its not expensive, but you'll need to find someone who can solder it for you.