Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
12 years ago

I/O Pins show 1.12V on scope

I have a small custom board that is just a fanout of the I/O pins and PLL and dedicated Clock pins using a EP3C40 (Quad Plastic 240 pin pack) FPGA. I have scoped out several I/O and dedicated CLK pin...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
12 years ago

Are you using a voltmeter? If yes you really need to see your signal with a scope. If it is oscillating the DC level shown by the voltmeter doesn't really mean a lot.

Some unused pins, or pins used as inputs, can be connected to the bank's VCCIO through a weak pull-up. This could be what you see. Do you know the pin's bank I/O voltage?