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m-labs / migen

A Python toolbox for building complex digital hardware
https://m-labs.hk/migen
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Can't use TIG on same TNM as period constraints in ISE #43

Closed mithro closed 8 years ago

mithro commented 8 years ago

Because ISE is retarded, if you have anything other than period constraints on a TNM_NET (such as a TIG), then it is unable to trace the constraints through any of the clock elements like PLLs and DCMs. See https://github.com/timvideos/HDMI2USB-misoc-firmware/issues/210 for a lot more info.

The solution for ISE is to generate two TMN with different names on the same signals and use one only for period constraints and another for TIG constraints.

This means that https://github.com/m-labs/migen/commit/cd55748edd3618c136127c337df1fe33b93c92ee#diff-15950acffd0d546d5f0722a73827c20aR203 should be changed so it uses a name other then GRP. Will send a patch soon.

mithro commented 8 years ago

This should be fixed in https://github.com/mithro/migen/commit/6d484a74dde84996d53f22e32f4a6e947450fa1e will send to the mailing list now.

I'm unsure how to test as my primary project is still stuck on the legacy branch of migen...