Open Source Summit + ELC Europe 2019

Many of the Arm Cortex-M based development boards supported by the Zephyr RTOS have an on-board chip that acts as a debug probe. This is typically based on the ARM Mbed DAPLink open source project. This provides the developer with several interfaces: USB MSD for drag-and-drop programming, USB CDC-ACM for console output and a CMSIS-DAP based debug channel over USB HID. The DAPLink project uses the Keil RTX OS and requires the Keil MDK-ARM or ARM Compiler 5, which makes it impossible to build it on Linux based systems.

​The talk is about whether it would be possible (and how) to build a debug probe on top of the Zephyr RTOS. Zephyr already has a reasonably stable USB device stack with CDC-ACM and MSD support. The author will give a overview about the structure of a debug probe, Host Interface Cirtuit, Serial Wire and SWD protocol. Furthermore, the author will introduce the implementation of the CMSIS-DAP in Zephyr RTOS.