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Altera_Forum's avatar
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

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The signals connected to the CPLD pins will have a weak high applied to them. If an external device drives the signal on the CPLD, then it will over-ride the weak pull-up.

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Thank you. And just to be sure - when an external signal overrides this weak pull up it will not damage the CPLD as the pins will be in tri-state?