Devkit Mxchip: IoT Plug And Play component name

[chandra-rayaprol]

The "component_name" and "component_name_len" argument values defined in the 'writable_property_received_cb' and 'property_received_cb' methods are always null. Also I noticed that the 'property_name' argument value contains the name of the component instead of the property. Could someone please look into this issue and advise?

[ryanwinter]

Hi @RaysApps,

Writeable properties within components hasn't been tested in this sample, let me take a look and see if I can see what is going on.

[ryanwinter]

Nothing immediate jumps out, did you modify the same to use components with the DTDL model? Is there something you can share?

The current sample only contains writable property within the base DTDL component which in this case is why the component is always empty.

[chandra-rayaprol]

Thanks for your quick response. I've added a new MxChip Model "dtmi:com:raysapps:mxchipapp:mxchipapp;1" with 3 components.

1. MxChipSettings
2. MxChipSensors,
3. MxChipTelemetry.

The Model is publicly available in the repo "https://raysapps.github.io/DeviceModels/"
Please try with Model ID "dtmi:com:raysapps:mxchipapp:mxchipapp;1" to reproduce this issue.
Best Regards,
Chandra Mohan

[ryanwinter]

Hi @RaysApps,

I found the problem, there needs to be a call after the hub is initialized to register the components so that they can be received correctly. This requires some restructuring of the code because at the moment the individual boards dont have access to configuration of the hub after its created so I will likely add a post connect callback so the devkits can add the required configuration.

[ryanwinter]

Fixing in #341

[ryanwinter]

Hi,

I have merged up the change.

There is a new function call:
https://github.com/azure-rtos/getting-started/blob/0912a22143750e49593a3c740782bb9e1dc6e853/shared/src/azure_iot_nx_client.h#L133

You will need to call this in nxclient, somewhere around this line:
https://github.com/azure-rtos/getting-started/blob/0912a22143750e49593a3c740782bb9e1dc6e853/MXChip/AZ3166/app/nx_client.c#L392

This allows the parser to recognise the components when parsing the json and correctly call the callback.

[ryanwinter]

Let me know if you have any more questions or issues. This is still a relatively new and untested codebase and parsing components in json on an embedded device is more complex than I wish it was.

[chandra-rayaprol]

Hi @ryanwinter,
I've implemented the suggested code changes that are specific to my custom PnP model. I am pleased to say that your suggested fix is working perfectly. I can see the relevant values in the functions 'component_name' and 'property_name' arguments.
Currently, I am making other code changes required to completely support the custom model. 
As of now, there are no further queries and I am happy to say that this issue can be considered as resolved.
Best Regards,
Chandra Mohan

[chandra-rayaprol]

Hi @ryanwinter
I did further testing and found another issue. I have a few pre-initalized desired properties in the device twin created using the IOT SDK from my backend server. While debugging, I found that the component name value appears only the first time in the 'property_received_cb' callback and is missing in the subsequent calls. Could you please check this at your end?
Please see the attached images for reference.

// Desired properties snippet "properties": { "desired": { "mxChipSettings": { "pk": 0, "screenLine0": "FirstUpdate", "screenFormat1": 1, "screenFormat2": 3, "screenFormat3": 5, "rgbLEDR": 100, "rgbLEDG": 100, "rgbLEDB": 100, "rgbLEDState": false, "userLEDState": false, "__t": "c" },

Best Regards,
Chandra Mohan

[ryanwinter]

Hey,

I see the issue, let me investigate to understand if this is a problem with the sample, or with the SDK itself. It looks like the SDK isnt behaving how I expect.

Ryan

[ryanwinter]

Hi @RaysApps,

I have isolated the problem which is a bug in the SDK itself. I am raising the issue with the team to roll out a fix.

In the mean time, if you want to make the change in your local code, you need to modify this line:
https://github.com/azure-rtos/netxduo/blob/93aff552c9e85c3b96f7ae62d0cdf48649d641ea/addons/azure_iot/nx_azure_iot_hub_client_properties.c#L190

To be the following:
component_name = az_span_create((UCHAR *)*component_name_pptr, (INT)*component_name_length_ptr);

Notice the pointer deference for the component_name_pptr variable.

Thanks for helping isolate this issue!

Ryan

[ryanwinter]

I have submitted a PR to the netxduo repository: https://github.com/azure-rtos/netxduo/pull/111/files

[chandra-rayaprol]

Hi @ryanwinter ,
Thank you for the fix. I've tested locally and it's all resolved now.