[chbot] Nucleo

[Mark Atherton]

Forget all about having to use DMA to get the ADC 
to run. Man, that was a headache.

We went bare-metal, so no issues with performance.

Still amused at the idea of 'openOCD', but not the debugger.

-mark


At 01:35 p.m. 21/10/2014, Stephen Irons wrote:
>We did a project using an STM32, all written in 
>C. We tried C++, but found it difficult to keep 
>the code size down. Perhaps we could have explicitly forced the EC++ subset.
>
>If you have enough performance for your 
>application, it does not matter which core you 
>use. You choose the language: C or C++ or Lua. 
>An ARM xx core is an ARM xx core, whoever makes the chip.Â
>
>You get different peripherals from different 
>manufacturers, and that is what you are really 
>choosing. You use an Arduino because of the libraries, not because of the core.
>
>The ST peripherals were pretty good, with a wide 
>range of useful functions, mostly involving DMA:
>    * AD converter with simultaneous sampling 
> with DMA to a memory buffer (up to 8K), with an 
> interrupt when nearly full. Good for high-speed 
> sampling, though you have to make sure your processing does not fall behind.
>    * DMA on SPI peripherals, so sending data to 
> the small LCD (128x64 or so) took little overhead.
>    * Free-running timer/counter which can reset 
> on input change, and trigger outputs, and 
> trigger DMA, so we made an RS-485 driver that 
> would wait for line idle for a length of time, 
> then enable the output driver some time later, 
> then a bit later trigger the DMA to start 
> transmitting data, all under hardware control; made for nice reliable timing.
>Peripheral docs were ok. I still like the TI docs best.
>
>However, the library functions provided by ST 
>(STM-SIS or something) to configure the 
>peripherals were pretty bad. We did use them, 
>and they worked, but they were slow. Fine for 
>the application, because of the 72 MHz clock, but...just offensively slow.
>
>We used gcc and gdb, running on Linux. We used 
>the Codesourcery tools (now Mentor Graphics), 
>though it would have been easy enough to compile 
>our own cross-toolchain. The Codesourcery tools 
>are still available free from Mentor Graphics, 
>but they make it difficult to find the free ones.
>
>We used a Ethernet connected JTAG debug adapter, 
>which speaks GDB directly. It was easy enough to 
>connect to Eclipse, though it was a bit funky 
>getting the code into the flash. $expensive (many K).
>
>We also made a serial GDB stub that we linked in 
>with the application, so we could debug via a UART.
>
>Other projects at the company have used OpenOCD. 
>That was 4 years ago or so: it might be better 
>now, but I remember a lot of blue air around 
>that team -- OpenOCD was flaky and the cheap USB 
>hardware was slow. $cheap, though.
>
>
>
>On 21 October 2014 10:08, Jasper Mackenzie 
><<mailto:jasper.mackenzie at gmail.com>jasper.mackenzie at gmail.com> wrote:
>So, on the topic of dev boards...
>Â We are about to begin a new project 
>redesigning the open source BMS for EV Lithium 
>stacks, but will be using STM32 chips which I 
>have absolutely no experience with.
>
>The prototype board is already on the way apparently!! (No pressure)
>
>The idea is to start with a Nucleo which seems 
>crazy cheap at only $16 from Element14 (More expensive on DX!)
>
>Does anyone have any experience with these 
>devboards, or STM32, or more generally the Arm that they are (left?)?
>
>I come from a C on Arduino background 
>(ATMega328p), where C is sort of like basic without the goto's 8)
>Â Toolchain is hoped to be entirely GNU, mostly running in GNU/Linux.
>
>Cheers.
>
>Jasper
>
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