Serial Trace Commands

Some ARM-based devices implement a serial trace output using the SWO pin. This is available only when using the SWD interface, and it uses the JTAG TDO pin on the tool to sample the signal. This section describes how to configure the tool for capturing serial trace and how to read the captured serial trace data out of the tool.

Note that the hardware tool performs only raw data capture, storage, and forwarding.

All serial trace commands use vendor command 7 (0x87).

Note: The protocol described here is a custom implementation for SWO trace, which pre-dates that details in the CMSIS-DAP specification. The implementation is thus similar, but not identical.