QDEC example simple code

[Ali Rumane]

Hi,

I want to interface two QENC with nrf52840, I saw QDEC example and it works as expected.

The problem I am facing is that QENC has four pins of which two are for power and two are ENCA and ENCB. Since I don't have QENC LED, I have to sample let's say 25 samples per second directly, how to do that?

Also I tried connecting my QENC pins to QDEC A (pin3) and QDEC B (pin4), connecting QDEC LED as it is and tried the software, it didn't work.

Is there a simple code not simulator where I can test my actual hardware and the direction whether it is in positive direction or negative direction?

How to add two QDEC in a project?

Regards

SDK 15.2, Keil, nRF52840 DK

[Øyvind]

Hello again, 

I would recommend reading the QDEC chapter in the nRF852840 PS. Furthermore, have a look at the QDEC Peripheral Library in the SDK documentation. 

The problem I am facing is that QENC has four pins of which two are for power and two are ENCA and ENCB. Since I don't have QENC LED, I have to sample let's say 25 samples per second directly, how to do that?

For using off-chip mechanical encoders not requiring a LED, the LED output can be disabled by writing value 'Disconnected' to the CONNECT field of the PSEL.LED register. In this case, the QDEC will not acquire access to a LED output pin and the pin can be used for other purposes by the CPU.

To set the sample rate, use the function:

nrf_qdec_sampleper_set()

 

Also I tried connecting my QENC pins to QDEC A (pin3) and QDEC B (pin4), connecting QDEC LED as it is and tried the software, it didn't work.

See the answer above.  

Is there a simple code not simulator where I can test my actual hardware and the direction whether it is in positive direction or negative direction?

 Unfortunately, we do not have any examples of this sort. I recommend using the example we have and customize it for your use. 

Have a look at cases regarding QDEC here, here and here. 

Kind regards,
Øyvind

[Ali Rumane]

Hi

Thank you for pointing out specific topics.

I am able to read accdbl and acc values in NRF_QDEC_EVENT_REPORTRDY as you showed, I don't understand what they signify.

In table Sampled value encoding I saw the description but they are based on sample register and how to interpret direction based on accdbl and acc as they .

Can you please let me know how can I count pulses and time so that I can calculate speed with sign?

I know the formula

S = (C/CPR) / (T/60)

where,

C is no of pulses

CPR is constant for encoder

T is time in sec at which pulses were captured

[Øyvind]

Ali Rumane said:

I don't understand what they signify.

 ACC = Register accumulating all valid samples (not double transition) read from the SAMPLE register

ACCDBL = Register accumulating the number of detected double or illegal transitions

Ali Rumane said:

In table Sampled value encoding I saw the description but they are based on sample register and how to interpret direction based on accdbl and acc as they .

Not sure what you mean, the link points to the QDEC chapter.  The Sample Value Register contains Last motion sample. The value is a 2's complement value, and the sign gives the direction of the motion. The value '2' indicates a double transition. 

Ali Rumane said:

Can you please let me know how can I count pulses and time so that I can calculate speed with sign?

I'm sorry I don't know the formula. The Sampling and Decoding chapter explains how this works. 

[Ali Rumane]

Thank you for your help

I am reading ACC registers but values seems completely incorrect.

I used gpiote to count pulses and they seems to be fine.

Do you know some common reasons why it isn't working as expected?

I am planning to use gpiote and count risung edge pulses which seems okay for me as of now but still I think qdec should work somehow for my applcation.

Regards