Re: STM32F4 Discovery, communication and libraries

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Tue, 26 Aug 2014 15:38:33 -0700 (PDT), roy.emmerich@gmail.com wrote:

> [Mike]
> I know that AdaCore is working on comms libraries for the ARM Cortex M
> parts, but I don't know anything about the projected availability.

What "comms" libraries? Basically it does not make sense to have a library
beyond system's port I/O driver, because higher-level protocols have
nothing in common, e.g. AK, CSLIP, ModBus.

> [Roy]
> If they want adopters then they'd better get a move on!
> 
> 2. [UNSOLVED?] Libraries/examples: MODBUS RTU/Eth at the very least

ModBus is very straightforward to implement from scratch. There exist
commercial libraries of course, but you want it for free, I guess...

> I have yet to find a repository of libraries covering the major protocols
> (e.g. MODBUS, CAN, one-wire). There are quite a few in C. Would it be
> viable to just wrap these in Ada?

It depends. Usually middle-layer transports like ModBus, CAN have no use
without integration into some middleware framework. It is a bad idea to
communicate directly to them from the application, even if through a vendor
library.

Then, regarding CAN, the real problems are in the configuration, e.g. DBC
parsing or handling CANOpen. It is a very complicated stuff, which would be
very difficult to handle in an application without a middleware abstracting
away the mess.

And all protocols have issues with polling/event handling policy, you
wouldn't burden the application with that.

> It seems like a great short term
> solution but if we are using Ada to make things more stable, it hardly
> makes sense to use it merely to wrap (flakey) C libraries ;)

You will need lower-level vendor libraries, which are vendor (Vector, IXXAT
etc, I don't know what is the status of Linux CAN driver for ARM boards)
dependent and higher-level libraries implementing the upper-level protocols
like CANOpen.

> I'd appreciate any further feedback from members of this list.

I would try to use a Linux instead of running bare board. Debian for ARM is
available. It has a fully working GNAT FSF. [We successfully ran our
middleware (100% Ada) on an ARM board.]

AFAIK, AdaCore offers a cross compiler to ARM Linux. (It is a pain to use
native ARM GNAT).

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de