nRF9160 DK + Azure IoT Hub Direct Method

RE: nRF9160 DK + Azure IoT Hub Direct Method

Loker — Wed, 25 Nov 2020 13:48:10 GMT

Hi.

I got everything working now (the fix on the parsing of the rid solved it - I didn't use the topic.len when logging and assumed the error was still there).

Thank you for your help!

RE: nRF9160 DK + Azure IoT Hub Direct Method

JONATHAN LL — Mon, 23 Nov 2020 13:34:45 GMT

Hi,

If the print function is not set up correctly hen this might happen, using the following setup:

printf("Topic: %.*s\n", evt->topic.len, evt->topic.str);

should be a functioning solution unless there is something else that does not behave as it should. If you still have a problem could you provide the code you are using ?

Regards,
Jonathan

RE: nRF9160 DK + Azure IoT Hub Direct Method

JONATHAN LL — Fri, 20 Nov 2020 10:17:56 GMT

Hi,

Looking in to the problem and will update you when we have a solution or temporary workaround as soon as possible.

Regards,
Jonathan

RE: nRF9160 DK + Azure IoT Hub Direct Method

Loker — Thu, 19 Nov 2020 14:03:18 GMT

Hi Jonathan, thanks!

Your commit fixes the two first problems, but not the last problem. There's a bug when mqtt_rx.c is parsing the incoming packet in mqtt_handle_packet. The buffer is not reset between packets. Every time a new Direct Method has a _shorter_ topic than the previous, the last char from the topic in the previous message is still in the buffer and becomes part of the (incorrectly) parsed topic.

Here is an example:

This is what mqtt_rx.c is parsing (incorrect):
Topic: $iothub/methods/POST/Open/?$rid=1
Topic: $iothub/methods/POST/Close/?$rid=2
Topic: $iothub/methods/POST/Open/?$rid=32
Topic: $iothub/methods/POST/Open/?$rid=42
Topic: $iothub/methods/POST/Close/?$rid=5
Topic: $iothub/methods/POST/Open/?$rid=65
Topic: $iothub/methods/POST/Close/?$rid=7
Topic: $iothub/methods/POST/Open/?$rid=87
Topic: $iothub/methods/POST/Close/?$rid=9
Topic: $iothub/methods/POST/Open/?$rid=a9
Topic: $iothub/methods/POST/Open/?$rid=b9
Topic: $iothub/methods/POST/Close/?$rid=c

This is what Azure IoT Hub sent (what mqtt_rx.c should have parsed):
Topic: $iothub/methods/POST/Open/?$rid=1
Topic: $iothub/methods/POST/Close/?$rid=2
Topic: $iothub/methods/POST/Open/?$rid=3
Topic: $iothub/methods/POST/Open/?$rid=4
Topic: $iothub/methods/POST/Close/?$rid=5
Topic: $iothub/methods/POST/Open/?$rid=6
Topic: $iothub/methods/POST/Close/?$rid=7
Topic: $iothub/methods/POST/Open/?$rid=8
Topic: $iothub/methods/POST/Close/?$rid=9
Topic: $iothub/methods/POST/Open/?$rid=a
Topic: $iothub/methods/POST/Open/?$rid=b
Topic: $iothub/methods/POST/Close/?$rid=c

RE: nRF9160 DK + Azure IoT Hub Direct Method

JONATHAN LL — Thu, 19 Nov 2020 09:38:08 GMT

Hi Loker,

There is a pending commit here https://github.com/nrfconnect/sdk-nrf/pull/3358 on the Direct Method.
Hopefully this will solve your problems

Regards,
Jonathan