Can't establish LTE connection with CONFIG_NRF_MODEM_LIB_TRACE_ENABLED turned on.

[ludw]

I have built on the CoAP example a POST request to the server. This works now without any problems.

I do send the received signal power within my POST. To get the power I use the AT command: AT+CESQ

The problem arises after roughly 20 min where the code get stuck in the <at_cmd_write> function. The timer interrupt callbacks still working correctly.

To get a clue what the problem could be, I wanted to do a modem trace. But if I add the configuration : CONFIG_NRF_MODEM_LIB_TRACE_ENABLED=y, the code get stuck already in the modem_configure() function from the example.

What could be the problem, or how can I track down the problem?

I'm using the VS Code extension as my development environment, the SDK Version 1.7.0 and Modem Version 1.3.0.

My config files are:

0216.prj_qemu_x86.conf2335.overlay-carrier.conf

I'm not 100% sure if I configured everything correct that all of these are used for the west build.

Thanks in advance.

[Håkon Alseth]

Hi,

 

Could it be that you're seeing this restriction?

https://infocenter.nordicsemi.com/topic/nwp_042/WP/nwp_042/intro.html?cp=2_0_7_0

 

If that is the case, a power-cycle would fix the problem.

 

Kind regards,

Håkon

[ludw]

In the meantime I commented out the line with the AT command. The software now works without crashing for multiple hours. After about roughly 20 min, I sent an AT command via the LTE Link Monitor to test whether the AT commands work and received a timeout response. Right after a reset of the board, the AT commands works properly and I receive a response.

The board is still sending the data over LTE, while the AT commands are not working. I know that the data is being sent, because I receive them on the server.

If I understand you correctly, the data would not be sent if the modem is in a loop restriction.

Thank you for your help.

[Håkon Alseth]

Hi,

 

ludw said:

In the meantime I commented out the line with the AT command. The software now works without crashing for multiple hours. After about roughly 20 min, I sent an AT command via the LTE Link Monitor to test whether the AT commands work and received a timeout response. Right after a reset of the board, the AT commands works properly and I receive a response.

A timed out response in LTE Link Monitor can very well be the uart connection between your computer and the kit. Try resetting the PC application (CTRL+R) and reselecting the device in the drop down menu.

 

Kind regards,

Håkon

[ludw]

The LTE Link Monitor is working correctly. I reset the Monitor and the problem still exists. In addition, I receive the printk() outputs.

[Håkon Alseth]

Hi,

 

It sounds like the UART RX is disabled after some time, possibly due to a framing error or similar (ie. noise on the line).

As a test, could you try to comment out this line and see if the issue still exists? https://github.com/nrfconnect/sdk-zephyr/blob/v2.6.99-ncs1/drivers/serial/uart_nrfx_uarte.c#L1038

 

Kind regards,

Håkon

[ludw]

I think that is not the problem, because after the software on the NRF9160DK crashes on the line with the AT command (CPU goes to IDLE state) I still receive timer event notifications over UART in the LTE Link Monitor.

I think the modem does not response for some reason and because I use a blocking AT command, my software waits for the response forever.

Thank you for your help.