81 lines
2.9 KiB
Markdown
81 lines
2.9 KiB
Markdown
# zig-gpio
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**zig-gpio** is a Zig library for controlling GPIO lines on Linux systems
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This library can be used to access GPIO on devices such as [Raspberry Pis](https://www.raspberrypi.com/) or the [Milk-V Duo](https://milkv.io/duo) (which is the board I created it for and tested it with).
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This is my first Zig project, so I'm open to any suggestions!
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_There's a companion article available on my website: https://www.elara.ws/articles/milkv-duo._
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## Compatibility
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**zig-gpio** uses the v2 character device API, which means it will work on any Linux system running kernel 5.10 or above. All you need to do is find out which `gpiochip` device controls which pin and what the offsets are, which you can do by either finding documentation online, or using the `gpiodetect` and `gpioinfo` tools from this repo or from `libgpiod`.
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## Commands
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**zig-gpio** provides replacements for some of the `libgpiod` tools, such as `gpiodetect` and `gpioinfo`. You can build all of them using `zig build commands` or specific ones using `zig build <command>` (for example: `zig build gpiodetect`).
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## Try it yourself!
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Here's an example of a really simple program that requests pin 22 from `gpiochip2` and makes it blink at a 1 second interval. That pin offset is the LED of a Milk-V Duo board, so if you're using a different board, make sure to change it.
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```zig
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const std = @import("std");
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const gpio = @import("gpio");
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pub fn main() !void {
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var chip = try gpio.getChip("/dev/gpiochip2");
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defer chip.close();
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std.debug.print("Chip Name: {s}\n", .{chip.name});
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var line = try chip.requestLine(22, .{ .output = true });
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defer line.close();
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while (true) {
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try line.setHigh();
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std.time.sleep(std.time.ns_per_s);
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try line.setLow();
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std.time.sleep(std.time.ns_per_s);
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}
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}
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```
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For more examples, see the [_examples](_examples) directory. You can build all the examples using the `zig build examples` command.
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## Using zig-gpio in your project
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If you don't have a zig project already, you can create one by running `zig init-exe` in a new folder.
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To add `zig-gpio` as a dependency, there are two steps:
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1. Add `zig-gpio` to your `build.zig.zon` file
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2. Add `zig-gpio` to your `build.zig` file
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If you don't have a `build.zig.zon` file, create one. If you do, just add `zig-gpio` as a dependency. Here's what it should look like:
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```zig
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.{
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.name = "my_project",
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.version = "0.0.1",
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.dependencies = .{
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.gpio = .{
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.url = "https://gitea.elara.ws/Elara6331/zig-gpio/archive/v0.0.2.tar.gz",
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.hash = "1220e3af3194d1154217423d60124ae3a46537c2253dbfb8057e9b550526d2885df1",
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}
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}
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}
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```
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Then, in your `build.zig` file, add the following before `b.installArtifact(exe)`:
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```zig
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const gpio = b.dependency("gpio", .{
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.target = target,
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.optimize = optimize,
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});
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exe.root_module.addImport("gpio", gpio.module("gpio"));
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```
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And that's it! You should now be able to use `zig-gpio` via `@import("gpio");`
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