STM32 ITM/ETM trace example

This is an example on how to configure the TPIU/DWT/ITM/ETM blocks on a Cortex-M3 microcontroller for tracing the execution. Trace data is output from the TRACESWO pin.

Designed to run especially on STM32 Value Line Discovery board, but should be easily adaptible to other boards also. Note that the STM32F100 chip on value line discovery does not have ETM feature.

What this does:

1. Configures the trace pin to output TPIU formatted trace from both ITM and ETM.
2. Blinks a led, while monitored by ITM tracing.
3. Causes periodic interrupts, where it runs bubblesort while tracing it with ETM.

Trace configuration with OpenOCD

The file configure-trace.openocd contains an alternative way to configure tracing without modifying the actual executable.

Random notes

OpenOCD also has some built-in ETM configuration support. If anyone has an example on how to use it, I'm interested.

Atleast STM32F407 seems to require a few extra settings: ETM_CR to 0xd90 to set the trace port internal width. ETM_TEEVR to 0x6F to do something related to "start/stop resources"..