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-rw-r--r-- | docs/ice40.md | 17 | ||||
-rw-r--r-- | ice40/pcf.cc | 4 |
2 files changed, 21 insertions, 0 deletions
diff --git a/docs/ice40.md b/docs/ice40.md new file mode 100644 index 00000000..f142f078 --- /dev/null +++ b/docs/ice40.md @@ -0,0 +1,17 @@ +# iCE40 Architecture Documentation + +## PCF format reference + +PCF files contain physical constraints and are specified using the `--pcf` argument. Each (non blank) line contains a command; lines beginning with `#` are comments. + +Two commands are supported: `set_io` and `set_frequency`. + + set_io [-nowarn] [-pullup yes|no] [-pullup_resistor 3P3K|6P8K|10K|100K] port pin + +Constrains named port `port` to package pin `pin`. `-nowarn` disables the warning if `port` does not exist. `-pullup yes` can be used to enable the built in pullup for all iCE40 devices. `-pullup_resistor` sets the pullup strength, and is available on iCE40 UltraPlus only. + + set_frequency net frequency + +Adds a clock constraint to a named net (any alias for the net can be used). `frequency` is in MHz. + +_Note that this is a non-standard extension, not supported by the vendor toolchain. It allows specifying clock constraints without needing the Python API._
\ No newline at end of file diff --git a/ice40/pcf.cc b/ice40/pcf.cc index 8c61eb23..526b3d64 100644 --- a/ice40/pcf.cc +++ b/ice40/pcf.cc @@ -100,6 +100,10 @@ bool apply_pcf(Context *ctx, std::string filename, std::istream &in) for (const auto &attr : extra_attrs) fnd_cell->second->attrs[attr.first] = attr.second; } + } else if (cmd == "set_frequency") { + if (words.size() < 3) + log_error("expected PCF syntax 'set_frequency net frequency' (on line %d)\n", lineno); + ctx->addClock(ctx->id(words.at(1)), std::stof(words.at(2))); } else { log_error("unsupported PCF command '%s' (on line %d)\n", cmd.c_str(), lineno); } |