Matter setting CarbonDioxideConcentrationMeasurement value.

[filipmrazek]

Hello,

I am developing matter sensor and I would like to send data to `MeasuredValue` attribute of `CarbonDioxideConcentrationMeasurement` cluster. I followed this tutorial https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/protocols/matter/getting_started/adding_clusters.html. The only thing I changed is that I turned on CO2 cluster and its attribute `MeasuredValue`. I wanted to set the value with this piece of code:

Clusters::CarbonDioxideConcentrationMeasurement::Attributes::MeasuredValue::Set(cluster_id, co2_val);

, but it turned out `Set` function does not exist for `CarbonDioxideConcentrationMeasurement`.

All those `Set` functions are implemented in Accessors.h which is located in `sdk_path/modules/lib/mater/zzz_generated` and I wonder when was this folder generated and why it does contain `Set` functions for clusters used in the samples and not for others. I could implement my own "accessor" for the required cluster, but I would like to ask if I'm missing something, because there is no `Accessors.h` inside my src/zap-generated folder.

Thank you for your answer.

Best regards,

Filip Mrazek

[Maria Gilje]

Hi Filip,

Regarding your implementation you shared on May 15th:

The constructor you used is meant to be used when the kNumericMeasurement feature is not used. If you are using kNumericMeasurement you need to use the other Instance constructor.

If you are not using kNumericMeasurement, you can check if the Init() function returns an error code.

If both steps above are ok, the cases where SetMeasuredValue will not update the MeasuredValue attribute is when the input is the same as the current value or if the input value exceeds the limits for MeasuredValue (CheckConstraintMinMax).

Best regards,

Maria

[filipmrazek]

Hi Maria,

I'm not sure if I understand, but in the post I shared on May 15th I use the correct constructor with 4 arguments and the last one is measurement unit. In the post I used: `ConcentrationMeasurement::MeasurementUnitEnum::kPpm`. 

However, I figured out that the Init() function returns `CHIP_ERROR_INCORRECT_STATE`, but cannot find out why.

Ad MinMax constrain - I didn't set any MinValue or MaxValue, so they are Null and the function you suggested returns always true if they are Null

[Maria Gilje]

Hi Filip,

Yes, I see it now that you are using the constructor with four arguments. Apologies for the misunderstanding, you are correct and I was wrong in my previous reply.

filipmrazek said:

However, I figured out that the Init() function returns `CHIP_ERROR_INCORRECT_STATE`, but cannot find out why.

Alright, so the functions which can cause CHIP_ERROR_INCORRECT_STATE to be returned are IsValidAliasCluster(), emberAfContainsServer(), and registerAttributeAccessOverride() (https://github.com/nrfconnect/sdk-connectedhomeip/blob/v2.6.1/src/app/clusters/concentration-measurement-server/concentration-measurement-server.h#L350-L356). So the next step would be to find our the source for the error amongst those three functions.

Best regards,

Maria

[filipmrazek]

Hi Maria,

Thank you for sour response. I looked at the section you found and I found the problem. I had to add `

emberAfEndpointConfigure()` before `emberAfContainsServer(mEndpointId, mClusterId)`.
Now it works. Thanks for your help.