maximum QDEC sample frequency

RE: maximum QDEC sample frequency

ovrebekk — Wed, 26 May 2021 11:06:45 GMT

The QDEC was designed primarily for handling scroll wheels on mice, which doesn't require a very high sampling frequency. Supporting higher frequencies is not necessarily hard from a design standpoint, but could have implications for power consumption etc.

It should be possible to use the TIMER, GPIOTE and PPI modules to sample pulses at higher speeds, but this requires a bit more work on the implementation side to setup the peripherals and decode the results.

Best regards
Torbjørn

RE: maximum QDEC sample frequency

eh — Thu, 15 Apr 2021 12:45:59 GMT

I'm also wondering about this. Currently working on the nRF52840 and sampling encoder signals from a motor. But since the highest sampling frequency in the QDEC is 128us I can not runt the motor very fast. I would like to see a sampling frequency of at least a few tenths of kHz, that does not seem hard to achieve. Are there any reason for this low frequency limit on the sampling?

RE: maximum QDEC sample frequency

sebastiano.xinet — Tue, 24 Nov 2015 08:55:48 GMT

I see. And the sampling reliability is our initial problem so I think we follow your suggestion and use our external solution, that we have already tested and works good. Thanks again!

RE: maximum QDEC sample frequency

ovrebekk — Mon, 23 Nov 2015 20:12:48 GMT

If an external device is an option that would probably be best. I am sure you could hack something together with the nRF51 alone, but I doubt it would be a 100% reliable solution ;)

RE: maximum QDEC sample frequency

sebastiano.xinet — Mon, 23 Nov 2015 15:26:08 GMT

Yes, the movement is bi-directional. If other ways are much more complex to implement we'll use some external device to resolve our problem. Thanks anyway for the reply.

RE: maximum QDEC sample frequency

ovrebekk — Fri, 20 Nov 2015 15:25:22 GMT

As mentioned there are no quicker modes available unfortunately.
If you need to reliably detect a pulse quicker than this you would probably have to do it using the GPIOTE, PPI and TIMER modules, but that would make for a significantly more complex implementation.
I assume the movement is bi-directional (like a scroll wheel for mice) ?

RE: maximum QDEC sample frequency

sebastiano.xinet — Thu, 19 Nov 2015 11:17:00 GMT

Yes, we had already seen what spec sheet tells but we had also seen that the debounce filter, that is into the process of QDEC, work with a 1MHz sampling frequency. So, our question meant to ask if could be an alternative way to use that frequency also for the QDEC sample. Thank you.

RE: maximum QDEC sample frequency

RK — Wed, 18 Nov 2015 04:11:06 GMT

No it's not - the spec sheet for the nrf51x22 tells you the minimum sampling period for the QDEC is 128µs. That's it, that's the minimum.