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Trace Port

The Trace Port section sets the port and the speed used for tracing.

Serial Wire Trace Output

Trace Port Options

Serial Wire Output – UART/NRZ sets the Serial Wire Trace Output pin (SWO) for tracing. When selecting this option, also set the debug Port to SW in the Debug - J-Link/J-Trace Adapter section.

SWO Settings define the communication speed when Serial Wire Output has been selected as the trace channel.

Prescaler defines the divider that is used to calculate the SWO Clock. Values, from 1 to 8192, can be entered when Autodetect max SWO Clk is unchecked.

Clock shows the communication frequency.

Autodetect max SWO Clk configures the prescaler automatically for the highest possible Clock frequency that J-Link/J-Trace supports.

Errors detected are displayed below Autodetect max SWO Clk.

Sync Trace Port

ETM Trace Port Options

Sync Trace Port with n-bit Data directs the debugger to accept Instruction Trace data in 1, 2, or 4-bit format. When ETM Trace is enabled, make sure these settings match the settings specified in the Initialization File. Consult Configure Cortex-M Devices for Tracing.


  • You must choose one of the Sync Trace Port formats when using ETM.
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