Using nrf9160-DK and nrfCloud - Control GPIO from the nrfCloud

[RobertLukan]

There are many examples available where nrf9160 is reporting data to nrfcloud or some other service. However I cannot find an example where an external application over MQTT or nrfcloud REST API would perform an activity. I am using nrf9160DK as my dev board, I will port the code to Feather later on.

I guess I found a piece of code where this kind of connection is handled(multi service mqtt example), connection.c -> cloud_event_handler function -> case NRF_CLOUD_EVT_RX_DATA_GENERAL.

Somehow I got lost where to continue next. I guess I would know how to create another sensor(just recreate temperature example), however I would like to turn on/off a GPIO pin. I know how to any retrieve data from nrfcloud with Insomnia by using GET method. But I dont know how would I handle POST command in this case. 

It seems that legacy version of asset tracker had one example with Thingy:91, but it is not available anymore(or at least I cannot find it).

Thanks,

Robert

[helsing]

Hello Robert, I just wanted to let you know I have started looking at this.

[RobertLukan]

Great, thanks. FYI, I have been looking more into existing setup I have. I noticed that NRF_CLOUD_EVT_RX_DATA_GENERAL case is not triggered if I send message over NRFcloud console. I managed to push a data into shadow data by sending REST API (Patch) into desired/config. I am still missing the detail how can I use those fields in my application. Nevertheless, it would be good to have an example that covers the basis. 

[justin]

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/samples/nrf9160/nrf_cloud_mqtt_multi_service/README.html#remote-execution-of-modem-at-commands

By default, the MQTT multi-service sample can processes AT command messages sent from the nRF Cloud Terminal.
Those are handled by the NRF_CLOUD_EVT_RX_DATA_GENERAL case.

Did you try to send the example AT command: {"appId":"MODEM", "messageType":"CMD", "data":"AT+CGMR"}

[justin]

If you want to change the state of a pin on your device, you would need to add code in NRF_CLOUD_EVT_RX_DATA_GENERAL to handle the command that you create.

For example, you could define your command as follows:
{"appId":"GPIO", "pin": 1, "state" : 1}

[RobertLukan]

I managed to trigger NRF_CLOUD_EVT_RX_DATA_GENERAL with the message you have suggested by using terminal of nrfcloud. How could I send the same message without using the terminal ? I have tried to send the same content by using Insomnia and sending it as POST message to /messages but it does not work. My goal is to send this message by an external application by using REST API from nrfcloud.

[justin]

You can use the SendDeviceMessage endpoint to send data to your device.
The topic field in the message needs to be a topic your device is subscribed to. 
So if you are using a current version of the nrf_cloud firmware library (as the MQTT multi-service sample does), you can use the c2d/r topic, which would be formatted in your message as follows:
"d/<DEVICE_ID>/c2d/r"


An example curl command:

curl --location 'https://api.nrfcloud.com/v1/devices/<DEVICE_ID>/messages' \

--header 'Content-Type: application/json' \

--header 'Authorization: Bearer <API_KEY>' \

--data '{"message":{"test" : "hello world"}, "topic": "d/<DEVICE_ID>/c2d/r"}'

[RobertLukan]

It works nicely. Thank you for your quick and great support.