Weird output from serial port

[Ivan Popov]

Hello,

In short, my use case is that I'm trying to onboard a Thingy:91 to AWS IoT Core through the available code sample following this tutorial (and the related library description linked in it).

What I did successfully was: 

1. I managed to provision the certificates to the device (I can see them listed along with the default ones with the AT%CMNG=1 command).
2. I created a project from the sample (aws_iot), edited the required properties (AWS MQTT endpoint, device_id, topics, ...) and managed to build it in VSCode for the thingy91_nrf9160_ns target.
3. I flashed the resulting app_signed.hex file on the device with the Programmer application (it took ~50 seconds).

However, on rebooting the device in regular mode I get nothing in AWS IoT Core - nothing in the topics, nothing for the shadow.

I tried to get some clues from the serial terminal but all I get is a blank, black terminal. (Interestingly executing commands in the LTE Link Monitor is successful ...)

I tried to play a bit with the ports and their options but the only visible result was on the second (not the default for any of the previously (successfully) executed operations) port and it looked like the wrong Baud Rats was given:

Any ideas on how to proceed and how to determine what might be wrong? I've followed the tutorials as closely as possible, yet we're here.

Best regards,

Ivan Popov

[Ivan Popov]

Hello Håkon,

Your questions caught me a bit uneducated, so I had to see a few things before replying.

Some answers:

Håkon Alseth said:

Still no visible output on ttyACM0?

No. The only three lines I get in the ST's log when I select the Thingy are:

11:11:42.567

Selected device with s/n THINGY91_EFF429E9883D

11:11:42.614

Opened port with options: {"baudRate":115200,"path":"/dev/ttyACM0"}

11:11:42.638

Get terminal settings from persistent store THINGY91_EFF429E9883D.vCom-0.TerminalSettings

I can still execute commands though. If I put AT%CMNG=1 and press enter it either returns 'ERROR', or properly gives me the list of the provisioned certificates ...

Håkon Alseth said:

Same thing with other serial consoles, like putty/minicom etc?

Haven't tried before. With Putty (the following settings - default for the ST too) nothing happens when I click 'Open':

Minicom is completely new for me, and I'd need some time with it in order to get used to it.

Håkon Alseth said:

Could you uncheck the hardware flow control, to ensure it is off?

I'm not sure how to do that.

Håkon Alseth said:

This has references to subimage "b0" - do you have CONFIG_SECURE_BOOT=y set in your current configuration?

I suppose this is the default and I haven't touched it:

So far I've always flashed the built apps according to the rules in the documentation (pressed SW3 while switching on SW1, and MCU Boot option switched ON) ... So far I haven't had a case where in the Programmer the green area (the image layout reaches above the half of the designated area (assuming 100% is to the top)).

But in this case I can't know - the build fails and I don't get to the HEX image to flash. 

Do you mean that the build is limited to a specific memory size and would fail if the image gets calculated to become larger?

Regards,

Ivan Popov