Firmware for CoreSight Debug Access Port

CMSIS-DAP is a Protocol specification and a implementation of a Firmware that supports access to the CoreSight Debug Access Port (DAP).

The various Arm Cortex processors provide CoreSight Debug and Trace. CMSIS-DAP supports target Devices that contain one or more Cortex processors. A Device provides a Debug Access Port (DAP) typically either with a 5-pin JTAG or with a 2-pin Serial Wired Debug (SWD) interface that connects to a Debug Unit. CMSIS-DAP is the interface firmware for a Debug Unit that connects the Debug Port to USB. Debuggers that execute on a host computer connect via USB and the Debug Unit to the Device which runs the application software.

CMSIS-DAP Overview

Configuration of CMSIS-DAP Firmware

The CMSIS-DAP Firmware version 2 can be configured in two different USB interface modes:

• Version 1 configuration uses USB HID as interface to the host PC.
• Version 2 configuration uses WinUSB as interface to the host PC and provides high-speed SWO trace streaming.

Benefits of CMSIS-DAP

• 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 of Cortex-M devices (new in CMSIS-DAP Version 1.1.0).
• Easy to deploy to Debug Units based on Cortex-M microcontrollers.
• Debug Unit may be integrated on an evaluation board.
• USB using HID (Human Interface Device) driver class that avoids driver installation on host PC.
• Supports time-critical JTAG or SWD command execution (new in CMSIS-DAP Version 1.10).
• Supports Test Domain Timer for time measurement using the debug unit (new in CMSIS-DAP Version 1.2.0)
• Supports UART Communication Port, which can be routed to USB COM Port (optional) or native CMSIS-DAP commands (new in CMSIS-DAP Version 2.1.0).

CMSIS-DAP Firmware

The CMSIS-DAP Firmware is provided as source code and is fully configurable to a new Debug Unit. A source code template and several reference implementations for popular Debug Units are provided. Refer to Firmware Configuration for more information.

The CMSIS-DAP Software Stack is composed of the following components:

• CMSIS-DAP Firmware that interfaces to JTAG or SWD Debug pins using standard I/O pins of the Cortex-M device.
• CMSIS-Driver USART that connects:
  • UART of the Cortex-M device to the SWO output from the target,
  • additional UART of the Cortex-M device to the UART from the target.
• USB Communication Stack that interfaces to the USB Port of the Host Computer using:
  • HID or custom class,
  • CDC ACM class to export USB COM Port.
• The USB Device middleware may require CMSIS-RTOS and a CMSIS-Driver USB.

CMSIS-DAP Software Stack

In the examples provided the MDK Version 5 USB Communication Stack has been used. However it is possible to use alternative USB stacks instead.

The CMSIS-DAP Firmware is provided in the following directory structure.

Directory	Description
.\CMSIS\DAP\Firmware\Config	CMSIS-DAP Firmware configuration
.\CMSIS\DAP\Firmware\Examples	CMSIS-DAP Firmware adapted to various Debug Units
.\CMSIS\DAP\Firmware\Include	CMSIS-DAP Firmware header file
.\CMSIS\DAP\Firmware\Source	CMSIS-DAP Firmware source code
.\CMSIS\DAP\Firmware\Template	Interface Templates for MDK Version 5 middleware

Validation

CMSIS-DAP compliant Debug Units must be validated using the scripts provided in Validate Debug Unit.

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