nRF52840 DTM Can not communicate with device.

[lian sheng]

Hi,

I made a BLE module with nRF52840, but an error occurred when testing DTM.

I have successfully compiled the project, but when I use nRF Connect-Direct Test Mode, the connection always fails.

I didn't make any modification to the code, because I confirmed that the RX TX definitions are the same.

How can I solve this issue?

The following is my test environment and schematic.

IDE : SEGGER Embedded Studio for ARM 7.10a

SDK : nRF5_SDK_17.1.0_ddde560

Project file: nRF5_SDK_17.1.0_ddde560\examples\dtm\direct_test_mode\pca10056\blank\ses

nRF Connect for Desktop v3.12.0 ; Direct Test Mode v2.0.3

schematic:

Thanks,

Sheng

[Jørgen Holmefjord]

Hi,

How is the UART pins of the module connected to the PC where you are running nRF Connect DTM application? By default, our DKs have P0.06 and P0.08 connected to the interface MCU on the DK to create a virtual COM port to the nRF52 chip on the DK to run the DTM commands. If you do not have this connection, the DTM commands will not work.

Best regards,
Jørgen

[lian sheng]

Hi Jorgen,

The module UART is connected with USB to TTL.(HW flow control is not connected.)

I tried TX RX swap but same result.

In other applications, my module works fine (including UART).

Thanks,

Sheng