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Feb 13, 2025
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Update docs #17

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583022c
license: update year and make consistent with main repo
deadprogram Feb 13, 2025
883b034
docs: additional info about how to install and use this package
deadprogram Feb 13, 2025
653177d
tweaks
soypat Feb 13, 2025
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2 changes: 1 addition & 1 deletion LICENSE
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BSD 3-Clause License

Copyright (c) 2023, TinyGo
Copyright (c) 2023-2025 The TinyGo Authors. All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
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34 changes: 34 additions & 0 deletions README.md
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# pio

[![Build](https://github.com/tinygo-org/pio/actions/workflows/build.yml/badge.svg)](https://github.com/tinygo-org/pio/actions/workflows/build.yml)

Provides clean API to interact with RP2040's on-board Programable Input/Output (PIO) block.
See chapter 3 of the [RP2040 datasheet](https://datasheets.raspberrypi.com/rp2040/rp2040-datasheet.pdf#page=310) for more information.

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set pins, 0 ; Drive pin low
jmp again ; Set PC to label `again`
```

### How to install pioasm

To develop new code using PIO with this package, you must build and install the `pioasm` tool. It can be be built from the pico-sdk:

```shell
git clone [email protected]:raspberrypi/pico-sdk.git
cd pico-sdk/tools/pioasm
cmake .
make
sudo make install
```

### How to develop a PIO program

To develop a PIO program you first start out with the .pio file. Let's look at the Pulsar example first.

1. [`pulsar.pio`](./rp2-pio/piolib/pulsar.pio): specifies a binary PIO program that can be loaded to the PIO program memory.
2. [`all_generate.go`](./rp2-pio/piolib/all_generate.go): holds the code generation command on the line with `//go:generate pioasm -o go pulsar.pio pulsar_pio.go` which by itself generates the raw binary code that can be loaded onto the PIO along with helper code to load it correctly inside `pulsar_pio.go`.
3. [`pulsar_pio.go`](./rp2-pio/piolib/pulsar_pio.go): contains the generated code by the `pioasm` tool.
4. [`pulsar.go`](./rp2-pio/piolib/pulsar.go): contains the User facing code that allows using the PIO as intended by the author.

### Regenerating piolib

```shell
go generate ./...
```

### Other notes

Keep in mind PIO programs are very finnicky, especially differentiating between SetOutPins and SetSetPins. The difference is subtle but it can be the difference between spending days debugging a silly conceptual mistake. Have fun!