https://github.com/peterschwarz/clj-gpio

A basic library for reading, writing and watching GPIO signals on a Raspberry PI, in a REPL-friendly way.
https://github.com/peterschwarz/clj-gpio

clojure gpio-port raspberry-pi

Last synced: 4 days ago
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A basic library for reading, writing and watching GPIO signals on a Raspberry PI, in a REPL-friendly way.

• Host: GitHub
• URL: https://github.com/peterschwarz/clj-gpio
• Owner: peterschwarz
• License: epl-1.0
• Created: 2014-05-08T18:35:23.000Z (almost 11 years ago)
• Default Branch: development
• Last Pushed: 2016-01-05T20:49:28.000Z (about 9 years ago)
• Last Synced: 2024-12-15T13:39:53.283Z (2 months ago)
• Topics: clojure, gpio-port, raspberry-pi
• Language: Clojure
• Homepage:
• Size: 64.5 KB
• Stars: 76
• Watchers: 7
• Forks: 5
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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# clj-gpio

A basic library for reading, writing and watching GPIO signals on a Raspberry

Pi, in a Clojure REPL-friendly way. Now, also targets ClojureScript.

## Usage

Add the following to your `project.clj`

    [clj-gpio 0.2.0]

Fire up a REPL, and require `gpio.core`.

### GPIO Read/Write 

We can open a basic read/write gpio port as follows (let's say we have an LED

conncted to GPIO 17):

    user=> (require '[gpio.core :refer :all] :reload)

    nil

    user=> (def port (open-port 17))

    #'user/port

To read the value of the port, we can do the following:

    user=> (read-value port)

    :low

To set values on the port, The port needs to be configured for `out` mode:

    user=> (set-direction! port :out)

This also works with `'out` and `"out"`.  A value can be written to the port

as follows:

    user=> (write-value! port :high)

With our LED connected to gpio 17, we should see it turned on.  We can also

read back the value and see that `(= :high @port)`.

We can also toggle the state, for convenience:

    user=> (toggle! port)

which will flip the state from `:low` to `:high` or vice versa.

### GPIO Listening.

We can also pull events off of a gpio port by using `open-channel-port`.  In

addition to setting directions, values etc, we set the edge change that we'll

listen for, and we can create a `core.async` channel from which can receive

values. 

For example (if we have a push button on GPIO 18):

    user=> (def ch-port (open-channel-port 18))

    #'user/ch-port

    user=> (set-direction! ch-port :in)

    ...

    user=> (set-edge! ch-port :both) ; or :falling, :rising, and :none to disable 

    ...

 We'll also set the bit to :high when the button pressed:

    user=> (set-active-low! ch-port true) 

Let's turn on the LED we defined in the Read/Write example above when our

button is pressed: 

    user=> (def ch (create-edge-channel ch-port))

    #'user/ch

    user=>  (require '[clojure.core.async :as a :refer [go  (go (loop []

             (when-let [value (

When we're finished with the channel, we call:

     user=> (a/close! ch)

     nil

And clean up our ports:

    user=> (close! port)

    nil

    user=> (close! ch-port)

    nil

## Development

First compile the java sources:

    lein javac

then fire up your REPL and require `gpio.core` as usual.

Note, the edge channel will only operate on the Raspberry PI platform.

## License

Copyright © 2014 Peter Schwarz

Distributed under the Eclipse Public License, the same as Clojure.