Raspberry PI

Tue Nov 27 21:40:13 UTC 2012

I have been looking into this myself. Although part of the chip is closed ( mostly the GPU ), the ARM and peripherals are documented. 
In addition, there is a growing amount of non-linux code available for study ( since the GPL bits could not be copied into RTEMS )

u-boot and freeBSD port:
http://kernelnomicon.org/?p=178

FreeRTOS:
https://github.com/jameswalmsley/RaspberryPi-FreeRTOS

ChibiOS:
https://github.com/steve-bate/ChibiOS-RPi

Plenty of examples in the "Bare Metal" Programming section of the Raspberry Pi forums:
http://www.raspberrypi.org/phpBB3/viewforum.php?f=72

Some other notes:
- There is a serial port available for a console: I used a $10 Serial to USB adapter from eBay on mine to get the u-boot console output.
- The ethernet chip on the board is actually a USB hub with a USB ethernet device. Not sure what to do here.. It would be nice to get the USB support in. 
- Supposedly the linux user land code for the GPU has been released, so the ability to create a graphics console is not out of the question.

As you can tell, I have been thinking about this a lot!

On Nov 27, 2012, at 4:21 PM, Steven Grunza <sgrunza at ctdi.com> wrote:

>> -----Original Message-----
>> From: rtems-users-bounces at rtems.org [mailto:rtems-users-
>> bounces at rtems.org] On Behalf Of Pierre Ficheux
>> Sent: Tuesday, November 27, 2012 3:59 PM
>> To: rtems-users at rtems.org
>> Subject: Re: Raspberry PI
>> 
>> Le 27/11/12 21:51, Angelo Fraietta a écrit :
>>> Does anyone know whether RTEMS would run on this
>>> 
>>> http://www.raspberrypi.org/
>>> 
>>> _______________________________________________
>>> rtems-users mailing list
>>> rtems-users at rtems.org
>>> http://www.rtems.org/mailman/listinfo/rtems-users
>> 
>> 
>> There is a page here, but empty:
>> 
>> http://code.google.com/p/rtemspi/
>> 
>> 
>> --
>> Pierre FICHEUX -/- CTO OW/OWI, France -\-
> 
> The FAQs for the RaspberryPI include the following:
> 
> What hardware documentation will be available?
> 
> Broadcom don't release a full datasheet for the BCM2835, which is the chip at the heart of the Raspberry Pi. We will release a datasheet for the SoC which will cover the hardware exposed on the Raspi board e.g. the GPIOs. We will also release a board schematic later on.
> 
> But I want documentation for <hardware X>!
> 
> Other documentation may be released in future but this will be at the Foundation's discretion.
> 
> But I demand the documentation for the chip. Give it to me!
> 
> To get the full SoC documentation you would need to sign an NDA with Broadcom, who make the chip and sell it to us. But you would also need to provide a business model and estimate of how many chips you are going to sell.
> 
> 
> What operating system (OS) does it use?
> 
> We recommend Debian as our default distribution. It's straightforward to replace the root partition on the SD card with another ARM Linux distro if you want to use something else (there are several available on our downloads page). The OS is stored on the SD card.
> 
> 
> 
> My $0.02 USD:
> 	It's an ARM11-based device but getting the details required to port RTEMS may not be easy.  You might need to reverse engineer from the Debian distro provided.
> 
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