Starting STM trace data capture

Note

If you already have a binary trace data file and would like to have it in a different format, see Converting trace data.

STM tracing uses dictionary-based logging to send messages without redundant strings. This is based on the Zephyr logging API's dictionary feature and is particularly useful for assisted multicore logging.

Complete the following steps:

Make sure you have configured your application for tracing. nrfutil trace stm requires that your application is compatible with the nRF Connect SDK v3.4.0 or later to work.
Identify the device's serial port for tracing by listing the connected devices:
```
nrfutil device list
```
Note

When selecting a serial port for the trace, pick the serial port with the highest serial port number.

Use the nrfutil trace stm command to start capturing logs from the device, specifying the tracing options - at least the database configuration for each domain ID, along with the input serial port.
Use the following command pattern:

nrfutil trace stm --database-config <domain_id>:build/<app_name>/zephyr/log_dictionary.json --input-serialport <serial_port>

In this command, the following parameters are used:

<domain_id> is the decimal ID of the domain (core) that the application is running on. When using several domains, use a comma to separate each domain in the list.
Use the following prefixes to indicate the cores:

Core	Prefix	ID
Secure Domain	`sec`	0x21
Application core	`app`	0x22
Radio core	`rad`	0x23
System Controller (SysCtrl)	`sys`	0x2c
Fast Lightweight Processor (FLPR)	`flpr`	0x2d
Peripheral Processor (PPR)	`ppr`	0x2e

<app_name> is the application name.
<serial_port> is the serial port used for output.
The decoded output is written to the console as ASCII by default. Use --output-type binary to change the format, --output-raw <PATH> to also write the raw trace data to a file, or redirect the output to save it as a file.

For example:

To capture logs from the Secure Domain and the application core, use the following command:

nrfutil trace stm --database-config 0x21:build/my_app/zephyr/log_dictionary.json,0x22:build/my_app/zephyr/log_dictionary.json --input-serialport COM10

To capture logs from the Secure Domain, the application core, and the radio core, use the following command:

nrfutil trace stm --database-config 0x21:build/my_app/zephyr/log_dictionary.json,0x22:build/my_app/zephyr/log_dictionary.json,0x23:build/my_app/zephyr/log_dictionary.json --input-serialport COM10

nRF Util starts to capture the log data from the specified serial port and uses the provided dictionary databases to decode the logs into a human-readable format. The tool sends the decoded logs to the console.

When done, stop tracing by pressing CTRL-C.

For more information about STM tracing with nRF54H20, see the nRF54H20 logging page in the nRF Connect SDK documentation. For more information about multidomain logging, see also Multi-domain logging using ARM Coresight STM in the Zephyr documentation.