dvlopt/linux-gpio

Use the standard Linux GPIO api from Clojure


Keywords
clojure, gpio, linux, standard
License
EPL-1.0

Documentation

dvlopt.linux.gpio

Clojars Project

Handle GPIO lines in a fast and portable way from Clojure.

Based on linux-gpio.java. Go there for rationale and background. In short, this API controls GPIO device from user space by using the "new" Linux API which is convenient, standard, and offers a some advantages over other methods (eg. automatic clean-up of resources when lines are released).

Usage

Read the API.

Have a look at the examples.

Attention, at least read permission is needed for the used GPIO devices, which is enough even for writing to outputs.

For instance :

(require '[dvlopt.linux.gpio :as gpio])


;; Alternating between 2 leds every time a button is released.
;;
;; After opening a GPIO device, we need a handle for driving the leds and a watcher
;; for monitoring the button. A buffer is used in conjunction with the handle in
;; order to describe the state of the leds.


(with-open [^AutoCloseable device         (gpio/device "/dev/gpiochip0")
            ^AutoCloseable led-handle     (gpio/handle device
                                                       {17 {::gpio/state false
                                                            ::gpio/tag   :led-1}
                                                        18 {::gpio/state true
                                                            ::gpio/tag   :led-2}}
                                                       {::gpio/direction :output})
            ^AutoCloseable button-watcher (gpio/watcher device
                                                        {22 {::gpio/direction :input}})]
  (let [buffer (gpio/buffer led-handle)]
    (loop [leds (cycle [:led-1
                        :led-2])]
      (gpio/write led-handle
                  (gpio/set-lines buffer
                                  {(first  leds) true
                                   (second leds) false}))
      (gpio/event button-watcher)
      (recur (rest leds)))))

License

Copyright © 2018 Adam Helinski

Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.