Information Needed

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


Simon,
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: http://www.rtems.org/onlinedocs.html

Manuals for developing RTEMS applications:
http://rtems.org/onlinedocs/doc-current/share/rtems/html/

Doxygen for the cpukit ( but why is that directory called cpukit? )
http://www.rtems.org/onlinedocs/doxygen/cpukit/html/

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:
http://git.rtems.org/rtems/tree/c/src/lib/libbsp/arm/lpc32xx/misc/i2c.c

2. A driver for libi2c similar to the one in the arm/lpc24xx BSP:
http://git.rtems.org/rtems/tree/c/src/lib/libbsp/arm/lpc24xx/i2c

This readme file gives a pretty good overview of libi2c:
http://git.rtems.org/rtems/tree/cpukit/libi2c/README_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.
https://github.com/pficheux/raspberry_pi

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

Alan









On Mon, Sep 9, 2013 at 5:20 AM, Simon Williams <williamssimonp at gmail.com>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.
>
>
> _______________________________________________
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> rtems-users at rtems.org
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>
>
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