Godot-GPIO

A Godot/GDScript addon to access GPIO on linux hosts (eg Raspberry Pi).

Setup

Godot-GPIO (ggpio) depends on lg:

1. install rgpiod on the computer you want to control (eg Raspberri Pi).
2. run it: sudo rgpiod (or start it as a deamon: sudo nohup rgpiod
3. on your host (where the ggpio will be running, possibly the same host,
   depending on you situation) install rgs

Requirements

• on Raspberri Pi: sudo apt-get install rgpio-tools
• others: download & compile rgs using lg's install info:

   wget http://abyz.me.uk/lg/lg.zip
   unzip lg.zip
   cd lg
   make
   sudo make install

Introduction

Here's a quick rundown of the main classes:

• ggpio: class_name'd to make it globally available, it can be considered a
  namespace for the project, so that no other gd script needs to be imported in most cases.
• ggpio.SBC: (Single Board Computer). That's the host we'll be interacting with.
• ggpio.Chip: refers to a gpiochip under the kernel's GPIO driver interface.
  Most of the time we're working with gpio 0.
• ggpio.GPIO: this is a single pin on a board.

• ggpio.devices.*: those are high level facilities to help development. See #facilities for details.
• ggpio.lg: this is where the low level lg/rpio interface is implemented. The flow is to create an LGCommand and run it on an SBC. This is for more advanced use.

Usage

In a nutshell:

# turn on LED on gpio 27 using the gpio itself
var sbc_hostname := 'rpi.local'
var sbc := ggpio.SBC.new(sbc_hostname)
gpio27 = sbc.open_chip().open_gpio(
	27,
	ggpio.Mode.OUTPUT,
	ggpio.LineFlag.PULL_DOWN,
	ggpio.Level.LOW
)
gpio27.write(ggpio.Level.HIGH)
assert(gpio27.read() == ggpio.Level.HIGH)

For more, check out scenes in the samples directory. Couple points:

• Each scene can be played independently (F6)
• the main scene is GPIO explorer, kind of a live version of the pinout above,
  but dedicated to GPIO:

Note:

• by default, ggpio connects to localhost, ie it access GPIOs of the board
  it runs on.
• set LG_ENVADDR & LG_ENVPORT to work remotely and access GPIOS of the board
  at those address & port.

Facilities

Devices

GGPIO implements a few abstractions similar to gpiozero
(this is very much a work-in-progress).

Legend:

• lighter classes are abstract
• darker ones are concrete / instanciable
• classes marked with a ✔ have been implemented
• classes marked with a ✖ are not written yet (I may lack the hardware to test them,
  contributions are welcome!)

flowchart RL
	Device[Device ✖]
	class Device abstract
	GPIODevice[GPIODevice ✖] --> Device
	class GPIODevice abstract
	RGBLED[RGBLED ✖] --> Device
	CompositeDevice[CompositeDevice ✖] --> Device
	class CompositeDevice abstract

	OutputDevice[OutputDevice ✔] --> GPIODevice

	DigitalOutputDevice[DigitalOutputDevice ✔] --> OutputDevice
	PWMOutputDevice[PWMOutputDevice ✔] --> OutputDevice

	Buzzer[Buzzer ✖] --> DigitalOutputDevice
	LED[LED ✖] --> DigitalOutputDevice

	PWMLED[PWMLED ✖] --> PWMOutputDevice

	Servo[Servo ✖] --> CompositeDevice
	Motor[Motor ✖] --> CompositeDevice
	PhaseEnableMotor[PhaseEnableMotor ✔] --> CompositeDevice
	TonalBuzzer[TonalBuzzer ✖] --> CompositeDevice

	AngularServo[AngularServo ✖] --> Servo


	classDef abstract fill:#d4ffa6,stroke:#000
	classDef default fill:#86bc4c,stroke:#000

Logging

Godot-GPIO logs under 4 levels:

• VERBOSE: to debug the lib itself. Will flood your terminal.
• DEBUG: Logs most events and gives a verbose overview of what's happening in the lib.
• INFO: Default level.
• WARNING: for local errors detected within this lib.
• ERROR: when the underlying stack (rgs/lg) returns errors.

WIP Status

Not all of rgs API is implemented (but still available as raw commands). This is a work in progress
where contributions are welcome.

FAQ

Why spam rds subprocesses instead of doing a proper rgpio / GDExtension integration?

I know. I wish I had the time. I'm working on this as a side-quest for a hobby.
If the lib picks up, we'll plug a strategy pattern in, and add a native rpgio implementation.
Until then, this is a quick (to write) way to get Godot to play with the Pi.

Changelog

0.5.2

• fixed files missing in downloaded asset