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Altera_Forum
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14 years ago

Unused CPLD Pins

I have two CPLDs on my PCB that connect to a common SPI bus. In order to keep things simple I'm trying to talk to only one of the chips at first but I'm having some trouble with the voltages which le...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
14 years ago

Oh, I'm so sorry. Long day at work! Yes, there's no 22 Ohm resistor. The schematic is slightly out-dated. I AM using 22 Ohm resistors in place of 100. Considering that, do you think it's bus contention?

What does "output driving ground" really mean? Does it imply that the pin is LOW?

Secondly, when I choose "tri-stated but with weak pull up", are the pull-ups internal to the chip or am I supposed to connect them?