Re: Implementing real-time embedded system to sample from five SPI ADCs

[Nicholas Kinar <n.kinar@usask.ca>]

> Hi Nicholas,
>
> according to what I understood, you want to use the data coming from 
> your ADCs in a userspace application which implements the control loop.
>
> I think there is a good chance you can then do all the steps (1)-(3) 
> within an userspace application. However, I am not 100% certain about 
> the best solution to implement (2) on this setup. May be anybody else
> knows something about the maximum sample frequency, but this also 
> depends on how complicated your algorithms are.
>
> Here [1] you can find a good example on how to write a RT userspace 
> application. Using the SPI character devices it should also be 
> possible to talk to your hardware.
>
> Regards,
> Andre
>
>
> [1] https://rt.wiki.kernel.org/index.php/RT_PREEMPT_HOWTO
>
>

Thanks, Andre; that is a very good link, and thank you for the 
information.  I am hoping that I can sample from the ADCs at a rate of 
at least 1 kHz, and I am wondering if it is best to do this in a 
userspace program or in a kernel driver.

My processing algorithms are not very complicated.  If one of the ADC 
data values is greater than a certain value, then a digital-to-analog 
converter (DAC) control register is updated.  All that I want to do is 
to collect data at a rate of 1 kHz by toggling a port pin and then 
reading the data values over SPI.

Nicholas