NRF9160 Modem Trace not working

[mlang3440]

Hi,

I am trying to capture a modem trace to send to Nordic for analysis, however Nordic says they are unable to open the ones I've captured so far. I am using the NRF9160 with a custom board.

My method for capturing a modem trace is:

1. Configuring UART1 in the devicetree to the USB VCOM port (Essentially swapping UART0 and UART1, so the output is modem trace instead of logging).
   1. We also tried using other pins as the UART1 TX,RX and capturing the modem trace through them.
   2. The baud rate is set to 115200
2. Add CONFIG_BSD_LIBRARY_TRACE_ENABLED=y to the projects prj.conf
3. Send the AT CMD AT%XMODEMTRACE=1,2 during program initialization
   
4. Open the nRF Connect Desktop Appliction (v3.3.0) and the Trace Collector App (v1.0.0)
5. Selecting the com port connected to the modem trace output.
6. Starting capture when the device is running, or resetting the device and starting capture at the same time.
7. Stopping the capture after we have recorded the events we are trying to capture.
8. Copying the bin file and sending to Nordic.

Is there anything I am missing or doing wrong that might affect the modem trace?

Thanks

[Håkon Alseth]

Hi,

 

Your steps shall be sufficient in order to get a valid modem trace, as per this guide: https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/how-to-get-modem-trace-using-trace-collector-in-nrf-connect

 

The baud rate is set to 115200

 It'll get overriden to 1M: https://github.com/NordicPlayground/fw-nrfconnect-nrf/blob/master/lib/bsdlib/bsd_os.c#L409

Might be that your usb-uart bridge has issues with this baud rate? Have you tried capturing the trace with another uart bridge?

 

Kind regards,

Håkon

[mlang3440]

Do you know if starting the modem trace when the application has already started running has any negative effect? Does the device need be reset at the same time the modem trace is started?

[Håkon Alseth]

As long as the AT command returns success, that should work.

When starting logging in trace collector, you should see that the file size increases in the order of kB/s, especially in the beginning of your program.

 

If you have issue wrt. setting %XMODEMTRACE, try running it first in at_client, and send a AT+CFUN=0 afterwards. This will store it persistently inside the modem configuration, and when you flash your own application afterwards, the traces will be default on. You'll still need the CONFIG_BSD_LIBRARY_TRACE_ENABLED=y set in your config.

 

Kind regards,

Håkon

[phipi]

It looks like the trace is enabled by default in the lte link controller initialization when CONFIG_BSD_LIBRARY_TRACE_ENABLED is set. Why does it need to be set separately by the application?

#if defined(CONFIG_BSD_LIBRARY_TRACE_ENABLED)
/* Enable modem trace */
static const char mdm_trace[] = "AT%XMODEMTRACE=1,2";
#endif

static int w_lte_lc_init(void)
{
...
#if defined(CONFIG_BSD_LIBRARY_TRACE_ENABLED)
    if (at_cmd_write(mdm_trace, NULL, 0, NULL) != 0) {
        return -EIO;
    }
#endif

[Håkon Alseth]

Hi,

  

phipi said:

It looks like the trace is enabled by default in the lte link controller initialization when CONFIG_BSD_LIBRARY_TRACE_ENABLED is set. Why does it need to be set separately by the application?

phipi: You are right, it shall be handled by lte_lc. I thought that feature went in after v1.1.0 was tagged, but it went in just before, my apologies. 

 mlang3440: Did you try another USB/UART bridge, in case yours have issues with 1MBaud?

As mentioned, you should see a higher order of kB/s, especially at boot-up.

 

Kind regards,

Håkon

[kk2mkk]

mlang3440 : I hope the answer in this post will help in fixing your problem,

https://devzone.nordicsemi.com/f/nordic-q-a/63007/hardware-requirements-for-collecting-modem-traces

regards

KK