Overview

A command line program for controlling BlinkM leds connected to the I2C bus of a embedded Linux machine.

The program uses the built-in i2c-dev Linux driver to talk to the BlinkMs. The i2c-dev driver exposes i2c busses to user programs as /dev/i2c-* entries.

To avoid having to specify the i2c bus on every run of the program, the bus number is hard coded in i2c_functions.c

The default assumes a Raspberry Pi 2 board using /dev/i2c-1

If you are using a v1 RPi board or a Gumstix Overo or other embedded Linux system with i2c drivers built in, then edit i2c_functions.c appropriately before building.

The required change should be self-explanatory. You need to tell the software what /dev/i2c-X bus to use. It's hard-coded so you don't have to specify it on every use.

Building

There is a make file for building the project.

    $ git pull git://github.com/scottellis/blinkm.git
    $ cd blinkm
    $ <optional> edit i2c_functions.c
    $ make

Running

RPi kernels might not load the i2c drivers automatically. If you are running the Debian Wheezy image, you can add the following two lines to /etc/modules

    i2c_dev
    i2c_bcm2708

Gumstix kernels load the i2c drivers by default.

You might need to change permissions for /dev/i2c-* device if you are running blinkm as someone other then root.

The current RPI Raspbian O/S adds the pi user to the i2c group so there should not be any permission problems.

On other O/Ses, a one-time fix is to run the following as root (Gumstix example)

    chmod 0666 /dev/i2c-3

This will get overwritten on your next boot though.

A more permanent fix is to create a udev rule file like this

    /etc/udev/rules.d/90-i2c.rules

With the following single line

    KERNEL=="i2c-[0-3]", MODE="0666"

Run the blinkm program without arguments to get the available commands.

    $ ./blinkm

    Usage: blinkm <command> <args>

    The led address is optional and defaults to 0x09.
    Use a comma separated list to address multiple devices in one command.
    The color arguments are optional and default to zero.

    Available Commands
            find-leds 
            set-rgb [-d led] [-r red] [-g green] [-b blue]
            get-rgb [-d led]
            fade-rgb [-d led] [-r red] [-g green] [-b blue]
            fade-hsb [-d led] [-h hue] [-s saturation] [-b brightness]
            fade-random-rgb [-d led] [-r red] [-g green] [-b blue]
            fade-random-hsb [-d led] [-h hue] [-s saturation] [-b brightness]
            play-script [-d led] -s <script id or name> -n num_repeats
            stop-script [-d led]
            set-fade-speed [-d led] -f speed
            set-time-adjust [-d led] -t adjust
            show-scripts 
            read-script [-d led]
            write-script-line [-d led] -n line_no -t ticks -c cmd -a arg1[,arg2[,arg3]]
            set-script-length-and-repeats [-d led] -l length -n repeats
            set-address -d new_led_address

The first command you probably want to run is find-leds.

    $ ./blinkm find-leds

    Scanning I2C bus for BlinkM devices...
    Found a BlinkM at address 1 (0x01)
    Found a BlinkM at address 2 (0x02)
    Found a BlinkM at address 3 (0x03)
    Found a BlinkM at address 4 (0x04)
    Found 4 devices

TODO

1. Write script function hasn't been tested much.

2. Need to recover the bus after the command to change an led address. Right now you need to power cycle the led which is okay, but you also need to power cycle the overo or the i2c bus stays hung.

3. GetAddress is not implemented. Investigate if i2c broadcasts are possible with the overos.

4. Add code to read in scripts from a file.