Linux.I2C

Easily use I2C and its subset SMBus from Clojure JVM.

Based on linux-i2c.java which provides an API around the standard Linux interface for talking to slave devices.

Usage

This is a small overview, the full API is available on Cljdoc.

In short, without error checking :

(require '[helins.linux.i2c       :as i2c]
         '[helins.linux.i2c.smbus :as smbus])

;; Selects the relevant "/dev/i2c-X" bus from the filesystem.
;;
(with-open [bus (i2c/bus "/dev/i2c-1")]

    ;; Selects a slave device.
    ;;
    (i2c/select-slave bus
                      0x24)

    ;; Reads 8 bytes.
    ;;
    (i2c/read bus
              8)
    ;; => [...]

    ;; Writes a few bytes
    ;;
    (i2c/write bus
               [42 1 2 3])

    ;; Does a transactions, several messages without interruption.
    ;;
    (i2c/transaction bus
                     [{::i2c/slave-address 0x24
                       ::i2c/write         [42 1 2 3]}
                      {::i2c/slave-address 0x24
                       ::i2c/read          4
                       ::i2c/tag           :some-read}])

    ;; => {:some-read [...]}



    ;; A few SMBus operations.

    (smbus/quick-write bus)

    (smbus/read-byte bus
                     42)

    (smbus/write-block bus
                       43
                       [1 2 3])
    )

Libraries targeting specific devices

Here are examples of libraries leveraging theses utilities for targetting specific I2C slave devices:

• BME280, a triple temperature-humidity-pressure sensor
• MCP342x, a family of A/D converters
• Horter-I2HAE, a simple A/D converter

License

Copyright © 2017 Adam Helinski

Licensed under the term of the Mozilla Public License 2.0, see LICENSE.