QDEC on the nRF52840

[WesC]

using nRF5 SDK 17.1.0

Segger

I need some understanding of the QDEC.  if I connect a motor that has a A/B output at a 5KHZ rate.

what is the maximum rate at which the decoder can run?

what do i need to set the SAMPLEPER register to?  is 128uS preferred for faster decoder inputs?

I am looking to know position.  SO if I set the SAMPLEPER to a fast enough speed, what should i set the REPORTPER to?

is this expected to be larger for a longer sample period before events?

when i have the QDEC_EVENT_HANDLER() and do a event.data.report.acc

does this clear the accumulator?  or do i need to manually do this?

if manually do i set a task to RDCLRACC before i read the ACC in the event?

if so, how?

If I am not using the LED, do i just simply set ledpre =0 and there is no other setting needed?

thanks for you support

[Einar Thorsrud]

Hi Wes,

what is the maximum rate at which the decoder can run?

The sampling period (set in SAMPLEPER) can be down to 128us. So 5 kHz is too much. I don't see that there is any wait around that.

[WesC]

So at 128uS the sample rate is 7.8Khz.  if you need Nyquist we are talking 7.8 / 2 so 3.9Khz maximum? so if there are 4 states in a revolution the maximum RPM of the motor is 975Hz ?  is this correct?

[Einar Thorsrud]

Yes, that is my thinking as well.