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AR# 30946

Spartan-3E - At which stage are the I/Os configured with the programmed I/O standard?

Description

At which stage of the configuration process will the I/Os drive with the configured drive strength and slew rate?

Solution

Spartan-3E devices will configure the I/Os at the very end of the start-up sequence. By the time GTS is released, the I/Os will still be driving the default I/O standard. The new I/O Standard will be applied after the entire startup sequence has completed.

If a lower drive strength is being used and the I/O is set to drive a 1 initially, the device will drive the I/O at the increased drive strength for a couple of clock cycles.

To resolve this issue, the I/O can initially drive a 0 as opposed to a 1.

AR# 30946
Date Created 05/20/2008
Last Updated 12/15/2012
Status Active
Type General Article