CMSIS-DAP is a protocol specification and an open-source firmware implementation that provides standardized access to the CoreSight Debug Access Port (DAP) available on many Arm Cortex processors as part of the CoreSight Debug and Trace functionality.

Overview of CMSIS-DAP

CMSIS-DAP supports target devices that contain one or more Cortex processors.

A processor device exposes Debug Access Port (DAP) typically either with a 5-pin JTAG or with a 2-pin Serial Wired Debug (SWD) interface that is used as a physical communication with a debug unit.

CMSIS-DAP provides the interface firmware for a debug unit that implements the communication between the debug port of the device and USB port. With it, a software debug tool that runs on a host computer can connect via USB and the debug unit to the device where the application firwmare gets executed.

Access to CMSIS-DAP

• CMSIS-DAP GitHub Repo provides the full source code.
• CMSIS-DAP Documentation describes the implemented functions in details.

Key Features and Benefits

• Provides a standardized interface for debuggers. Interfaces to many standard debuggers is available.
• Access to CoreSight registers of all Cortex processor architectures (Cortex-A/R/M).
• Connects via 5-pin JTAG or 2-pin Serial Wire Debug (SWD).
• Supports multi-core debugging.
• Supports Serial Wire Output (SWO) of Cortex-M devices.
• Easy to deploy to debug units based on Cortex-M microcontrollers.
• Debug unit may be integrated on an evaluation board.
• Using USB bulk transfers avoids driver installation on host PC.
• Supports time-critical JTAG or SWD command execution.
• Supports Test Domain Timer for time measurement using the debug unit.
• Supports UART communication port, which can be routed to USB COM Port (optional) or native CMSIS-DAP commands.