[TriEmbed] ARM build breakthrough vis a vis FreeRTOS & Re: Nucleo boards for MBED and FreeRTOS

[Pete Soper]

(Heard the news about the A Centauri project as I was typing this. Wow!)

On 04/12/2016 09:10 AM, Alex Davis via TriEmbed wrote:
> Pete,
>
> I think the board you showed me last night was an NUCLEO-L476RG, right?
It's a 401RE. It has oodles of memory and compute power. I picked it 
because the MCU package is something I could very easily solder onto a 
custom PCB. This chip is available for roughly $9 in single quantity vs 
$11 for the chip in the 476 (Mouser).

By contrast, I'm also messing with bare ST M0 chips in TSSOP-20 
packages. One of these is 58 cents for quantity one from Digikey.

But let me tell you what Vikram brought last night. Vikram sent mail 
(the one with the build log) and he's onto something extremely exciting. 
I vaguely knew that mbed projects can be exported, but hadn't invested 
any time looking at this to confirm it will play with gcc on Linux.

(Finding that TI Code Composer Studio won't build TI's RTOS demo 
(because the "free" license is code size limited) really annoyed me, as 
I mentioned last night. I still intend to put my MSP432 boards to use, 
but for some simple, power sensitive utility application that doesn't 
involve heavy investment of time, and I'll use the multitasking Energia 
IDE for that.)

But I digress. Vikram and I got his KL25z board set up properly to 
support mbed (http://mbed.org) and he confirmed that projects can be 
exported from the mbed cloud environment to a local, Linux-based 
environment and they build and run properly. The KL25z (just as other 
mbed supported boards, like the Nucleo401 mentioned above) presents an 
automounted filesystem to a host computer and just dragging and dropping 
(i.e. copying) a .bin file into this filesystem causes the dev board to 
notice the file and reflash itself and start running the new program. 
Copying another program causes the first one to be replaced, and so on. 
It's very convenient. (But by the way, my trick to point my web 
browser's download path to the mount point has stopped working, at least 
for the two Linux systems by two browser combos I tested yesterday. Oh 
well.) Again, this mbed drag/drop programming is an area Gene Kahn 
explored over a year ago.

The cloud-based IDE provided by the mbed.org "classic" dev environment 
is fantastically powerful. It's well integrated with the Mercurial 
revision control system such that two folks can edit the same file and 
with minimal actions they can keep their edits sanely applied. Fetching 
libraries and programs from the collection created by others is 
absolutely trivial and the build speed is great. I fetched the entire 
mbed source tree and will be experimenting with doing development that 
would still work if the cloud tools were turned off.

Got to focus on other things, but I'm intending to explore FreeRTOS with 
various targets in coming weeks.

-Pete