Direct Test Mode v2.4.1 GUI does not work with third party boards

[lx_brz]

Using nRF Connect for Desktop on Ubuntu 24.04 LTS I am trying to use the Direct Test Mode v2.4.1 software with our own custom board.

On https://docs.nordicsemi.com/bundle/nrf-connect-direct-test-mode/page/index.html you wrote:

> The application also supports third-party devices that are programmed with the DTM standard protocol and expose access to it through a serial port.

But it is not possible. Trying to select the FTDI based UART and running clicking "Start test" I see the following error:

At the same time I am connected to the board via RTT to view logs and don't see any communication.

On the contrast when I use cutecom to send commands as hex codes directly, everything works as expected:

And I see the expected communication activity on the RTT logs:

Help would be much appreciated. It would be much more convenient to use your GUI based Direct Test Mode tool instead of sending and decoding the DTM commands as hex manually.

There are no problems by the way using a nrf52840DK. It only does not work with the custom board, connected via UART, although you explicitly write:

> The application also supports third-party devices that are programmed with the DTM standard protocol and expose access to it through a serial port.

Thanks

Alex

[lx_brz]

Charlie said:

Is your custom board also use nRF52840 or other chip?

Yes

Charlie said:

Is it also running Bluetooth: Direct Test Mode (nordicsemi.com) sample?

Yes

That both doesn't matter though, it rather seems that the nordic Direct Test Mode application does not even try to start communication.

Charlie said:

When you test DTM with nRF52840DK, do you use uart through onboard interface MCU or just usb port?

I'm plugging in the board where the connector is labelled "MCU USB", so it should be "uart through onboard interface MCU". The nordic Direct Test Mode application device selector then looks like this:

[Elfving]

Hello Alex, I'll be taking over this case for a sec as Charlie is currently busy.

So first of all I just wanted to mention that we do not officially support for nRF Connect for Desktop on Ubuntu 24, but that hopefully won't be a real issue in this case.

lx_brz said:

This seems to work without problems. Using it I can start transmitter tests and see the communication happening in RTT logs.

So I assume you mean that this project works on the third party board using the GUI that comes with it, but does it work with the nRF Connect for Desktop DTM app?

But it is not possible. Trying to select the FTDI based UART and running clicking "Start test" I see the following error:

Could you try pressing the button for "programming compatible fw" there in the GUI? Or is maybe the problem that you don't want it to work with just nordics FW, but any DTM fw?

lx_brz said:

That both doesn't matter though, it rather seems that the nordic Direct Test Mode application does not even try to start communication.

I believe it checks for compatible fw before doing anything else.

Regards,

Elfving

[lx_brz]

Elfving said:

So first of all I just wanted to mention that we do not officially support for nRF Connect for Desktop on Ubuntu 24, but that hopefully won't be a real issue in this case.

I'm aware of this and asked a colleague with a mac to try it. The result is the same.

Elfving said:

So I assume you mean that this project works on the third party board using the GUI that comes with it, but does it work with the nRF Connect for Desktop DTM app?

Exactly.

Elfving said:

Could you try pressing the button for "programming compatible fw" there in the GUI?

There is no programmer attached, only the serial connection, so there is no point in trying to press that button.

Elfving said:

Or is maybe the problem that you don't want it to work with just nordics FW, but any DTM fw?

Not sure what exactly you mean with "any DTM fw", but I have programmed the custom board with this sample: docs.nordicsemi.com/.../README.html

[Elfving]

lx_brz said:

Not sure what exactly you mean with "any DTM fw", but I have programmed the custom board with this sample: docs.nordicsemi.com/.../README.html

Great. DTM is a program defined by BT SIG, so there are multiple versions of this that I guess should act the same. Though if you maybe ran something like radio test, (which is similar to DTM, just better) the DTM app wouldn't work. 

lx_brz said:

There is no programmer attached, only the serial connection, so there is no point in trying to press that button.

I see. Well then I think that is the problem. DTM needs a COM port for it to work. Could you connect your DK to your third party board using a JTAG 10pin debug connector, and try the same thing again? You hopefully have support for that on your board. 

Regards,

Elfving

[lx_brz]

Elfving said:

Great. DTM is a program defined by BT SIG, so there are multiple versions of this that I guess should act the same.

I understand that. By the way: nordic has implemented some vendor specific extensions to the standardized "direct test mode" like constant carrier, see https://github.com/nrfconnect/sdk-nrf/blob/main/samples/bluetooth/direct_test_mode/src/dtm.c#L169

Elfving said:

I see. Well then I think that is the problem. DTM needs a COM port for it to work. Could you connect your DK to your third party board using a JTAG 10pin debug connector, and try the same thing again?

What would be the point of doing that? The DTM app can not possibly know which pins it must configure for UART on our custom board. So if I just click "program" and it flashes the same firmware as for the nrf52840DK, the chances are high that it will not work and will also stop working with the third party program I mentioned above, because probably our custom board does not use the same pins for UART communication as the nrf52840DK.

Also the serial port or "COM port" as you refer to it is available and functional, as the third party application demonstrates.

Sorry, I don't understand how this is supposed to help, maybe there is a misunderstanding somewhere?