Re: Ada, the best language with the not-so-best tool chain

[Ludovic Brenta <ludovic@ludovic-brenta.org>]

Patrick writes on comp.lang.ada:
> "Why are people so obsessed with ARM? You could have a decent
> Atom-based board for same money. AMD Geode LX could be an alternative.
>
> Anyway, the thingy should run Linux. I believe there was a GNAT for
> ARM somewhere. Maybe others could point out its status. "
>
> Yes but my main point was the lack of GPIO, please comment on this

The Raspberry Pi has, IIRC, 17 GPIO ports.  See it in action here:

http://www.youtube.com/watch?v=RuYLTudcOaM

For what it's worth, here is my opinion on your problem as you describe
it.

* bare-metal programming is _very_ difficult in any language.

* there are so many options to choose from that none is "standard"
  enough to gather a community around it; whatever "bare metal" you
  chose, you'll be alone or almost alone with it.  The various
  processors and µcontrollers are just one aspect of this diversity; at
  the bare metal level, each and every other device on the board
  (e.g. Flash storage, USB, GPIO, whatnot) has its own peculiar
  programming interface.  That's why GNAT supports so few bare-metal
  targets.

* learning bare-metal programming (especially the most difficult part:
  the bootstrapping process) can distract you from building software
  that works.

* I think you should consider basing your development on the Raspberry
  Pi.  It is inexpensive and has the necessary GPIO ports.  It is
  powerful enough that you can program natively on it, avoiding the
  pesky issues of cross-compiling and programming in an environment with
  no memory protection or filesystem.  Yes, that means you'll run
  GNU/Linux on it.  Why should that be a problem?

* once you have built *software* that satisfies your needs on the
  Raspberry Pi, you can *then* look at porting it to an even smaller
  device.  Then you will tackle the difficult bootstrapping and
  toolchain problems.

* Nobody has yet mentioned the Lego Mindstorms, which AdaCore (with
  their staffing and expertise) have programmed to the bare metal. They
  provide a multitasking kernel and a cross-compiler, for free!  If that
  particular target doesn't meet your hardware requirements, you can at
  least base your hypothetical bare-metal toolchain on it.

Last thing: I think your quest is so noble that it deserves
encouragement and help; but you are getting distracted by hardware and
toolchain problems that you imagine and do not fully understand; I think
you should rather spend your time solving the problem that you do
understand - helping children with disabilities to communicate.  It
doesn't matter if your first device has wires all over it, so long as it
works.  If you can demonstrte such a device, you'll be in a position to
attract funding to develop dedicated hardware and bare-metal software.

-- 
Ludovic Brenta.