Raspberry Pi 2 Model B Bare Metal Reference Design

Not sure if this is what you are after, but perhaps give this one a go:

https://github.com/dwelch67/raspberrypi/tree/master/blinker02

Hi Brett,

There is a wikibook for it here: https://en.wikibooks.org/wiki/Bare-metal_Raspberry_Pi_Programming

I can understand it for academic purposes, but otherwise bare metal on the Pi is likely to end up vastly under-using the Pi, and doesn't easily allow the use of libraries of code (that rely on Linux being the OS). The chip on the Pi is designed to run an OS (as opposed to a microcontroller which of course can still run an OS, but has hardware facilities/resources designed for smaller OSs or bare-metal.

If you wish to flash an LED in assembler or in C code, that is possible under Linux too. If you're looking for real-time behavior, that is just as easy or just as difficult bare-metal, as it is under Linux.

Anyway, it is certainly feasible to go bare-metal on the Pi if you wish. There is also a combined bare-metal and assember forum, there seem to be posts regarding tutorials on bare-metal: https://www.raspberrypi.org/forums/viewforum.php?f=72&sid=12f91dca053fc05f8a82644c6ed66099

shabaz, thanks for the information.  And yes, I understand that I can blink an LED under Linux.  However, the one thing I can't do under Linux is understand how the bootloader works (which is the root purpose behind my question).

As for the forum reference, that's what I was referring to when I said I've been searching for the past couple days - it's easy to find RPi3 references, but RPi2 seems more difficult to locate.

Gough,

Thanks for the reference - I'll take a look at all of the projects in that tree and see if I can find one that will help.  The README on the one that you suggested indicates that there's a RPi2 version, but indicates that it's in a directory that is not present at that link.

I will post again when I've looked through all of the projects on there - hopefully there's one that contains the RPi2 stuff :-)

Whoops - sorry, copy and pasted the wrong link:

https://github.com/dwelch67/raspberrypi/tree/master/boards/pi2

That's probably the one you need

- Gough

Hi Gough!

That looks exactly like what I was looking for.  I'll try it out this weekend (wish I had time to do it now) and let you know how it goes.

Any tips on how you found it?  I'm sure at some point I'll have a RPi 3 (or later when they make one) and will probably be back to the same thing.

Again, thanks so much - I was starting to think the information wasn't out there or was just hidden so well I'd never find it :-)

Brett

Dear Brett,

No specific hints, but I saw that the latest commits by dwelch67 referenced the pi2:

thanks to ultimo and others I think I have the pi2 switching back to …

 

…svc and secure mode now.

 

and other cleanup

I checked the file changes and stumbled upon the /boards/pi2 area which gave away the location which was where the previous example's README should have pointed to, along with the /SVC subdirectory where pi2-specific versions of the examples reside. The diff shows the changes, I presume, from the previous pi2 code which probably had the pi2's CPU running in a different mode.

- Gough

Hi Brett,

The "rpidmx512" project is bare-metal and works on raspberry pi 2. So google for the term download the sources and look around. There are also prebuilt images, so that you can test the code to eliminate "compiler issues".

So much changed since then - now we have Circle, a really mature RPi BM framework. Posted about it a /technologies/code_exchange/b/blog/posts/going-bare-metal-on-raspberry-pi-431574917

I'm not sure if you are aware but the post you made is to content that is five years old. I see by your membership points you are a new member. The anomaly of an old post suddenly looking like there new is a gremlin that continues to haunt the site. I myself have posted to aged out content because it suddenly appeared and it was a topic of interest. Unless you were reviewing old material and thought to post on something, my comments may be unnecessary.