RE: Getting RTT Logging with J-Link Probe and nRF54L15DK

Kazi Afroza Sultana — Tue, 22 Jul 2025 13:53:48 GMT

Hello,

''
- Find a way to use the VCOM0 (The serial port that doesn't end with a 3)''

yes, in principle you can do this, dedicate one UART (e.g., VCOM0) for HCI tracing and other one is for your application logs. You need to configure your firmware so that the HCI trace output is routed to the UART instance connected to VCOM0.

''But I can't seem to get the J-Link Probe to work with''

For the second one, you can check that you are using the latest version of the jlink RTT software and debugger is correctly connected to the PC.

To capture and decode these traces, you should use the btmon tool from BlueZ with the --jlink option, specifying your device and serial number. For example:

btmon --jlink nRF54L15_xxAA,<your_jlink_serial_number>