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diff --git a/machxo2/examples/README.md b/machxo2/examples/README.md index f82da63a..87f50f6d 100644 --- a/machxo2/examples/README.md +++ b/machxo2/examples/README.md @@ -10,7 +10,20 @@ This contains a simple example of running `nextpnr-machxo2`: using the [`iverilog`](http://iverilog.icarus.com) compiler and `vvp` runtime. This is known as post-place-and-route simulation. -As `nextpnr-machxo2` is developed the `nextpnr` invocation in `simple.sh` and -`simtest.sh` is subject to change. Other command invocations, such as `yosys`, -_should_ remain unchanged, even as files under the [synth](../synth) directory -change. +As `nextpnr-machxo2` is developed the contents `simple.sh` and `simtest.sh` +are subject to change. + +## Environment Variables For `simple.sh` And `simtest.sh` + +* `YOSYS`- Set to the location of the `yosys` binary to test. Defaults to the + `yosys` on the path. You may want to set this to a `yosys` binary in your + source tree if doing development. +* `NEXTPNR`- Set to the location of the `nextpnr-machxo2` binary to test. + Defaults to the `nextpnr-machxo2` binary at the root of the `nextpnr` source + tree. This should be set, for instance, if doing an out-of-tree build of + `nextpnr-machxo2`. +* `CELLS_SIM`- Set to the location of `machxo2/cells_sim.v` simulation models. + Defaults to whatever `yosys-config` associated with the above `YOSYS` binary + returns. You may want to set this to `/path/to/yosys/src/share/machxo2/cells_sim.v` + if doing development; `yosys-config` cannot find these "before-installation" + simulation models. |