Direct Test mode app v3.1.0 can't communicate with the device

RE: Direct Test mode app v3.1.0 can't communicate with the device

Jianxuan Tu — Mon, 09 Feb 2026 18:53:42 GMT

Thank you for the help! It worked with the new .hex

RE: Direct Test mode app v3.1.0 can't communicate with the device

Håkon Alseth — Fri, 06 Feb 2026 07:56:33 GMT

Hi,

[quote user="Jianxuan Tu"]How should I use this .hex file? [/quote]

Flash it to your DK using nRF Connect for desktop -> Programmer application. After a successful programming, power cycle the DK and start up the DTM application.

Kind regards,

Håkon

RE: Direct Test mode app v3.1.0 can't communicate with the device

Jianxuan Tu — Thu, 05 Feb 2026 22:26:04 GMT

Hi, Håkon,

Thanks for the response. How should I use this .hex file? I was trying the settings you recommended but it had the same error.

Best regards,

Jianxuan

RE: Direct Test mode app v3.1.0 can't communicate with the device

Håkon Alseth — Thu, 05 Feb 2026 13:57:45 GMT

Hi,

[quote user=""]

I was using the Direct Test mode app from the nRF desktop to try to run a DTM Tx Test on nRF54L15-DK. The app could find the device (but there're two serial ports xxx51/53). I tried both 19200 (recommendation in https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/samples/bluetooth/direct_test_mode/README.html) and 115200 BaudeRate but all had the error of "can't communicate with device".

Attaching the logs here, can you please help to see what's wrong and how should I config? Thanks.

[/quote]

The direct_test_mode, when compiled for nrf54l15dk, should be detected in the PC/desktop application, with a baud of 19k2.

On macos, specifically for nrf54l15dk, you want to choose the port that ends in "3".

Could you try this .hex file (stock ncs dtm example .hex file)? This worked at my end:

devzone.nordicsemi.com/.../dtm_5F00_nrf54l15dk.hex

Kind regards,

Håkon