On Tue, Feb 28, 2017 at 3:41 PM, Drew Fustini <[email protected]> wrote:
> > eCAP is interesting as there seems to be two modes: capture input, and PWM > output. The use of eCAP as PWM output is already supported in mainline as > part of epwmss. > > However, the eCAP input driver written Matt Porter is still out-of-tree > and carried as a patch by Robert. At least this my understanding after > chatting with Robert Nelson and Michael Welling last week. > > eCAP input seems to be another candidate to upstream. Question is which > subsystem fits best. > > You know I'm not really sure. I've never used the ecap module before, but my impressions form what I've read that the ecap is similar to a high speed ADC, except instead of "capturing" voltage levels. ecap captures logic level transitions. High's, to low, low to highs.. Again I'm not sure for this specific application, in terms of speed, but imagine a car with a high RPM engine at the drag strip. Where one could monitor the rotation speed of the engine's cam, and adjust engine timing based on engine RPM. I've discussed this a few times in the past with a person talking about maximizing an engines performance curve. But with an engine operating at let's say 30,000 RPMs, an ADC would need an insane amount of sample per second. I think at one time we calculated this out to somewhere around 2-3Msps minimum. With pulse counting however, which is all you'd really need an ADC for with this application. I think "samples per second" could be mitigated some. Of course with this application mentioned above. One would probably have to use the PRU's, but I'm also not sure in this case if the ecap module, the PRU's or the beaglebone board in general would be up to the task. Because not only would one need to count RPM pulses, but one for this application would have to act on those pulses. The X15 most definitely could handle this. Anyway, I'm not sure if that really helps with the question in general. It's just a thought I've had once in a while for several years now. I have had other ideas similar to this one where I *think* pulse counting could in fact be used instead of ADCs. For various other projects I've considered in the past. *shrug*. -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CALHSORp7Tf8jHOqeHGKNwG%2BLV9NmdQeA%3D27cUgm2jQ2ze403Gg%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
