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YosysHQ / nextpnr

nextpnr portable FPGA place and route tool
ISC License
1.31k stars 243 forks source link

Gowin IODELAY/IDDR/ODDR #928

Open sathibault opened 2 years ago

sathibault commented 2 years ago

I'm working on a project that makes use of these primitives. It does not look to me like they are currently available. What would be involved in adding support for these?

yrabbit commented 2 years ago

Adding support to nextpnr is not that hard, but figuring out which bits need to be set to enable this functionality, determining which points are responsible for which input and which output, finding out which cells in the chip can be used for this purpose and which cannot, figuring out how bits change to encode the same functionality on each of the supported boards - that's a bit harder. Because GOWINs are undocumented chips and you have to figure it all out by compiling examples and looking for bits in the image dump. That's what the apicula project does :)