jeffreyurban / nrf9160-google_iot_mqtt Goto Github PK

Comment on Nordic Devzone

"One thing that you should be aware of when connecting to GCloud. The JWT must be updated every 24 hours, according to the specified time limits. I can't see that the google_iot_mqtt sample does this, it should be updated."

Hello,
Well, I tried creating a topic in the iot core and tried to publish messages to it. I can see them when pulling from the subscription to that topic in the pub/sub service, but still in the nRF9160 I don't get any PUBLISH events.
Any idea on what's the reason for that?

Thanks,
Abdelali

Hello Jeff,
Thanks a lot for sharing this project example.
I had an issue with programming the cloud side certificates with the .crt extension. This command throws an error (file not found).

python3 cred.py \
  --CA_cert gtsltsr.pem \
  --sec_tag 202

I tried converting it to a .pem certificate, the cred utility programs it but its tag looks empty when looking for it in the Certificate Manager (nRF Connect App).

Thanks again

The MQTT publishing loop in protocol.c:331, inherited from the Zephyr google_iot_mqtt project does not attempt to reconnect in case the client is disconnected, but instead breaks out of the loop and exits.

When setting the Google Cloud IoT Core config payload to content of approximately 648 bytes or larger, the application crashes hard before handling the corresponding MQTT_EVT_PUBLISH event in protocol.c, resulting in no more console output. Crashes become more consistent with higher payload sizes, such as 768. Note that these payloads are smaller than the rx_buffer.

In experimenting with other similar MQTT code, such as in the nRF Connect SDK mqtt_simple sample, larger packet sizes are received OK, or generate an error publish_get_payload failed: -122 when the payload exceeds the buffer size.

Perhaps there is a difference on the Google Cloud IoT Core side that is not accommodated by Zephyr's MQTT library.