https://github.com/tokafish/pigpiox
An Elixir wrapper around pigpiod for the Raspberry PI
https://github.com/tokafish/pigpiox
elixir embedded nerves
Last synced: 6 months ago
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An Elixir wrapper around pigpiod for the Raspberry PI
- Host: GitHub
- URL: https://github.com/tokafish/pigpiox
- Owner: tokafish
- License: apache-2.0
- Created: 2017-08-20T04:06:35.000Z (about 8 years ago)
- Default Branch: master
- Last Pushed: 2022-10-05T17:06:51.000Z (about 3 years ago)
- Last Synced: 2024-04-23T13:09:35.359Z (over 1 year ago)
- Topics: elixir, embedded, nerves
- Language: Elixir
- Size: 28.3 KB
- Stars: 35
- Watchers: 3
- Forks: 23
- Open Issues: 7
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Pigpiox
Pigpiox is a wrapper around pigpiod for the Raspberry Pi. For all of pigpio's features, check out its [documentation](http://abyz.me.uk/rpi/pigpio/).
# Requirements
To use Pigpiox, pigpiod must be included in your firmware. Currently, this is included by default on `nerves_system_rpi0`, but not on other Pi systems.
If you'd like to use Pigpiox on one of those systems, customize the nerves system you're interested in, and add `BR2_PACKAGE_PIGPIO=y` to its `nerves_defconfig`.
# Installation
In your firmware's `mix.exs`, add `pigpiox` to your deps for your system target:
```elixir
def deps(target) do
[ system(target),
{:pigpiox, "~> 0.1"}
]
```
# Usage
Adding pigpiox as a dependency to your system will automatically launch the pigpio daemon and open a socket to communicate with it. To interact with pigpiod, Pigpiox provides various modules exposing different areas of functionality.
All documentation available on [hexdocs](https://hexdocs.pm/pigpiox/).
## GPIO
### Basic functionality
The `Pigpiox.GPIO` provides basic GPIO functionality. Here's an example of reading and writing a GPIO:
```elixir
gpio = 17
Pigpiox.GPIO.set_mode(gpio, :input)
{:ok, level} = Pigpiox.GPIO.read(gpio)
Pigpiox.GPIO.set_mode(gpio, :output)
Pigpiox.GPIO.write(gpio, 1)
```
### Watching a GPIO
When reading a GPIO, often it's useful to know immediately when its level changes, instead of having to constantly poll it. Here's an example:
```elixir
{:ok, pid} = Pigpiox.GPIO.watch(gpio)
```
After setting up a watch on a GPIO pin, the calling process will receive messages of the format `{:gpio_leveL_change, gpio, level}` as its level change.
## Waveforms
The `Pigpiox.Waveform` module provides functions that allow you to create and send waveforms on the Raspberry Pi. Here's an example of pulsing a GPIO on and off every 500ms:
```elixir
pulses = [
%Pigpiox.Waveform.Pulse{gpio_on: gpio, delay: 500000},
%Pigpiox.Waveform.Pulse{gpio_off: gpio, delay: 500000}
]
Pigpiox.Waveform.add_generic(pulses)
{:ok, wave_id} = Pigpiox.Waveform.create()
Pigpiox.GPIO.set_mode(gpio, :output)
Pigpiox.Waveform.repeat(wave_id)
```
## Clock
The `Pigpiox.Clock` module provides functions that allow you to set a clock on reserved pin.
```elixir
Pigpiox.Clock.hardware_clk(gpio, 2_500_000)
```
## Pulse-width modulation (PWM)
The [`Pigpiox.Pwm` module](https://hexdocs.pm/pigpiox/Pigpiox.Pwm.html#content) provides functions that allow you to build and send waveforms with pigpiod.
According to [Raspberry Pi's GPIO usage documentation](https://www.raspberrypi.org/documentation/usage/gpio/), here are the pins PWM is avaliable on:
- Software PWM: all pins
- Hardware PWM: GPIO12, GPIO13, GPIO18, GPIO19
### Software PWM
Max value for `level` is `255`. Here's an example of changing the brightness of an LED using software PWM.
```elixir
gpio = 12
Pigpiox.Pwm.gpio_pwm(gpio, 255) # 100%
Pigpiox.Pwm.gpio_pwm(gpio, 127) # 50%
Pigpiox.Pwm.gpio_pwm(gpio, 25) # 10%
Pigpiox.Pwm.gpio_pwm(gpio, 2) # 1%
```
### Hardware PWM
Max value for `level` is `1_000_000`. Here's an example of changing the brightness of an LED using hardware PWM.
```elixir
gpio = 12
frequency = 800
Pigpiox.Pwm.hardware_pwm(gpio, frequency, 1_000_000) # 100%
Pigpiox.Pwm.hardware_pwm(gpio, frequency, 500_000) # 50%
Pigpiox.Pwm.hardware_pwm(gpio, frequency, 100_000) # 10%
Pigpiox.Pwm.hardware_pwm(gpio, frequency, 10_000) # 1%
```
# Contributions
This library is still in a very early stage, and I'd appreciate any and all contributions. In particular, a short-term goal is getting feature parity with the [python](http://abyz.co.uk/rpi/pigpio/python.html) pigpiod client library.