If you don't specify IO standards, drive etc. in the UCF for a Spartan3, what default settings are used ?
What are IO standard defaults in S3 ?
Aug 09, 2005
2 Replies
Unless you specify otherwise, ISE sets the I/O standard to ...
- LVCMOS25
- 12 mA output drive
- SLOW slew rate.
The output will follow whatever voltage level you have connected to the respective VCCO input. In other words, even if ISE sets the I/O to LVCMOS25 and you have VCCO = 3.3V, the output will drive 3.3V levels.
However, it's best to always set the I/O level appropriately so the software can make sure that all your I/O assignments end up in the proper I/O banks.
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