While we’re waiting for the first interface boards to arrive we’ve been checking out our libraries against the new Raspbian distro.
The latest Raspbian kernel supports I2C and SPI, and today we got all our loopback tests passing. This means we have working Python libraries on Raspbian for GPIO, I2C and SPI.
Raspbian is now the official recommended kernel, so we’re fast approaching the point where a new Pi user can plug in our hardware, install our libraries, run an example and expect everything to work.
At the moment the Python GPIO library needs our gpio-admin library as well as the Python code. Soon we’ll package the two together as a .deb file, which will make things even easier. The gpio-admin and Quick2Wire Python libraries are on github so if you feel like experimenting, clone away and let us know how you get on! The libraries have examples and test code included.
If you want to try out the SPI code, you’ll need to upgrade to the latest Raspbian firmware. The kernel in the current Raspbian image (2012-07-15-wheezy-raspbian) supports I2C but not SPI; you can use Hexxeh’s firmware updater to get a later kernel, which supports both.
There are a couple of other things you’ll need to do: uncomment the two lines in /etc/modprobe.d/raspi-blacklist.conf which stop needed modules from loading, and add a line i2c-dev to /etc/modules to ensure that the relevant i2c module is loaded on boot-up.
Your raspi-blacklist.conf should then look like this:
# don't blacklist spi and i2c by default
# blacklist spi-bcm2708 # blacklist i2c-bcm2708
and /etc/modules should look like this:
# /etc/modules: kernel modules to load at boot time. # # This file contains the names of kernel modules that should be loaded # at boot time, one per line. Lines beginning with "#" are ignored. # Parameters can be specified after the module name.
snd-bcm2835 i2c-dev
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