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Honored Contributor
Honored ContributorUnused 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_ForumHonored Contributor
Honored Contributor --- Quote Start --- You'll have to read the MAX V handbook. They should be tri-stated, since their function has not been defined. Your pull-up will define the power-on state with a blank device. You can also program the devices prior to assembly. There are TQFP and BGA sockets available. For small numbers of boards, its easier just to use the JTAG to program the boards. Cheers, Dave --- Quote End --- Searching for the word "unprogrammed" in the databook lead me to this: --- Quote Start --- The programmable pull-up resistor is active during power-up, in-system programming (ISP), and if the device is unprogrammed --- Quote End --- So since the pull-up resistor is active it means the device must be tri-stated. I'm a bit confused by what you mean by --- Quote Start --- Your pull-up will define the power-on state with a blank device. --- Quote End --- How would my pull up resistors define the default state of the device?
