Direct Test Mode with USB

[kpreiss]

Hi,

There appears to be a bug in the implementation of Direct Test Mode over USB built from NCS v2.2.0.  When the Nordic DTM Desktop application attempts to initially communicate with the target running DTM over USB by pressing the "Start Test" button, an error is returned stating the app cannot communicate with the target.

Pressing the "Start Test" button a second time successfully runs the test.  All subsequent tests run successfully.  It appears to be an "initial condition" bug.

Through experimentation, we discovered if we simply use a 3rd party terminal application (i.e. RealTerm) and open and close the CDC port, then run the Nordic DTM desktop app, it works when we press the "Start Test" button the first time.

Unfortunately, this has caused some grief with the testing lab.  Can you please look into this and let us know if/when/what the solution is?

Thank you.

[Håkon Alseth]

Hi,

 

I see this issue in both NCS v2.2.0 and up to main (as of 11th of May).

I believe that this is a timing issue between the desktop application itself and the cdc acm line setting. Could you try to 'n' select this config?

https://github.com/nrfconnect/sdk-nrf/blob/v2.2.0/samples/bluetooth/direct_test_mode/conf/remote_shell/prj_usb.conf#L28

 

This will disable waiting for DTR (ie. the port to open and be configured)

 

Kind regards,

Håkon

[kpreiss]

Hi Hakon,

I modified the prj.conf file as you indicated and rebuilt the project using the following command line.

west build . -b nrf5340dk_nrf5340_cpunet -- -DCONFIG_DTM_USB=y

I programmed the application using "west flash" and the behavior still exists.

Thanks.

[Håkon Alseth]

Hi, 

 

The behavior is coming from the "remote shell", and its configuration is located in direct_test_mode/conf/remote_shell/prj_usb.conf.

If you set line 28 in the prj_usb.conf file to 'n', it should disable the DTR functionality and not require two initial start with DTM.

 

Kind regards,

Håkon

[kpreiss]

That worked.  Thank you!

[Håkon Alseth]

Glad to hear it worked on your end as well!

Hope you have a wonderful day!

 

Cheers,

Håkon