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I wish to upload measurement data to Google Cloud Platform IoT Core with Arduino MKR GSM 1400. I have followed:

https://docs.arduino.cc/tutorials/mkr-gsm-1400/securely-connecting-a-mkr-gsm-1400-to-google-cloud-iot-core

and

https://create.arduino.cc/projecthub/Arduino_Genuino/securely-connecting-a-mkr-gsm-1400-to-google-cloud-iot-core-b8b628

but I did not succeed on connecting to Google's MQTT broker.

I have seen that I am not the only one with this problem, but I hope that someone has figured out the solution to this problem.

Reading this:

https://groups.google.com/a/arduino.cc/g/developers/c/EK7lmDK-jTA?pli=1

I came to the realization that I might need to update the root certificate in the "radio module", aka SARA-U201. I've tried to figure out how to do this, and stumbled upon the arduino-fwuploader, I have tried to run it like this:

/arduino-fwuploader firmware get-version -b arduino:samd:mkrgsm1400 -a /dev/ttyACM0

in order to succeed with this:

./arduino-fwuploader certificates flash -b arduino:samd:mkrgsm1400 -a /dev/ttyACM0 -u mqtt.googleapis.com:443

but the fwupdater does not even find the board despite "arduino:samd:mkrgsm1400" being correct. And yes, I am trying to do all this under Linux.

I was also trying to make the example: "SSLCertificateManagement_Example" working, but for this I would have needed the certificates to be converted to DET format and arrange it to be an array of unsigned chars.

https://www.sslshopper.com/ssl-converter.html

At this point I don't know what else I should/could try. I know for a fact that the hardware itself is working, I have tried as many examples regarding GSM as I could (sending SMS, GPRS ping, initiating a voice call, detecting GSM networks, etc.), and all worked. Following the tutorial, I have properly locked the ECC508 crypto chip, and generated a private/public key into slot 0. I have a GCP account, configured it properly, I have even tried to disable the HTTP protocol in the GCP project registry, but no use, I still think that it is about updating the root certificate in the SARA module.

Did anyone figure this out yet?

Thank you for the related tips and ideas!

Balazs Bornyasz
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  • Your question is "how to upgrade root cert", but your description is more like "how to establish a SSL connection". Nobody will follow all the links you provided trying to guess how's your code looks like and what are you trying to do, it would be easier for you to post your code, and more importantly what shows on the Serial Monitor? So that it provides better understanding on whether it failed on establishing a SSL connection (which root CA will be used) or failed on authentication (which your public/private key) exchange mattered. – hcheung Jan 31 '22 at 01:17
  • Hi Hcheung, thank you for the feedback, I may have been less specific at places where I should have been more specific. I wanted to demonstrate what I have done to try to solve the problem. The complete code can be found under my first link in the original question. Near the end of the "comments" section of the second link people begin to write about the same problem, what I am facing: The code gets stuck at an endless loop (writing ascii "."-s) trying to connect to mqtt.googleapis.com. That's the point where I begun my investigation. – Balazs Bornyasz Jan 31 '22 at 10:38

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