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

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

On Tue, 9 Oct 2012 12:04:29 +0000 (UTC), Simon Clubley wrote:

> If, OTOH, you need to know what the voltage on the line actually is, then
> you choose a GPIO line which can be reconfigured as a A/D converter input
> and run it through the MCU's ADC. Sample rates of several thousand per
> second are still commonly achievable in this case.

The problem is that an integrated I/O usually has only on ADC. So to
measure two inputs you need twice so much time plus the time needed to
switch the ADC to another line. This is how you quickly come over 10ms. Not
to forget inability to measure inputs and change the outputs synchronously.
 
> Unless you can generate pulses with a accuracy of _well_ under 0.1ms at a
> rate of about 50Hz, you will see major jitter. You can control the pulse
> length on a AVR GPIO line to this degree of accuracy.

Under VxWorks we were able to receive, process and then send Ethernet
frames with the latency about 100�s. We didn't do such tests for Linux,
though.

>> And who is talking about performance while choosing an ARM?
> 
> It's the difference between latency and raw performance.

Yes. But even with many tasks active latencies under 100�s are doable. Not
for an ARM of course.

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