Information Needed

Alan Cudmore alan.cudmore at
Mon Sep 9 14:29:33 UTC 2013

In my experience, there is no single place to get all of the information
you need, especially for specific device driver development. In addition,
it has taken me a while to feel comfortable navigating the RTEMS source
tree and being able to quickly locate BSPs, drivers, and libraries.

Here are the docs that I know of:
Starting point:

Manuals for developing RTEMS applications:

Doxygen for the cpukit ( but why is that directory called cpukit? )

For the Raspberry Pi: I was hoping to start with the I2C driver shortly. It
seems there are two options:
1. A standalone I2C driver similar to the one in the arm/lpc32xx BSP:

2. A driver for libi2c similar to the one in the arm/lpc24xx BSP:

This readme file gives a pretty good overview of libi2c:

I was going to start with a simple i2c driver for the Rpi, then try to
implement a libi2c driver when I had a little more experience with it.

Same with the SPI/SD card access: I'm pretty sure I saw a good example of
using the SPI bus to access a SD card , but I can't find it right now (
exactly your point! )

Also, here is another GPIO driver for the Raspberry Pi. I was able to use
this for reading button states and lighting multiple LEDs.

But feel free to ask more questions: I would like to help with the I2c


On Mon, Sep 9, 2013 at 5:20 AM, Simon Williams <williamssimonp at>wrote:

> I have made some progress with the work I have been doing for the
> Raspberry Pi, but I am finding that progress is being held up due to lack
> of information about RTEMS.  Is there a repository of information I am not
> aware of?
> I have a GPIO driver which allows me to have an RTEMS task that switches
> an external LED on and off.  The is based on the description of the
> discrete driver in the BSP and Device Driver Development Guide, but that
> description is almost non-existent!  There also does not appear to be any
> sample implementation anywhere.  I have one specific issue with my
> implementation, which is that stat() does not return anything useful and so
> I have to use the deprecated RTEMS specific call to get information about
> the devices.  This leads me to believe that I have not got it quite right!
> My next targets are I2C, followed by a driver to put the console on an HD44780
> compatible display and keyboard attached to the I2C bus.  After that, I
> will be looking at an SD card filesystem and other I2C devices I need for
> my application.  I would be extremely grateful if anyone could point me
> towards some well documented examples of these sort of drivers for other
> boards, I would be grateful.  The problem with most of the examples I have
> found in the repository is that any documentation that they contain assumes
> that the reader has a good knowledge of RTEMS and it's requirements and it
> is that knowledge that I am trying to gain!
> I would also be interested to know if there is any documentation I have
> not been able to find on using the C++ class library as my application
> level code will be written in C++.
> Thanks in advance for your help.
> _______________________________________________
> rtems-users mailing list
> rtems-users at
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