xjtuecho / cmsis-dap

An ARM CMSIS-DAP debugger firmware on STM32 device.

CMSIS-DAP user manual

Overview

CMSIS-DAP provides a standardized way to access the Coresight Debug Access Port (DAP) of an ARM Cortex M0 M0+ M3 M4 MCU via USB. It provides direct USB connection from a development board to a debugger running on a host computer on one side, and over JTAG or SWD to the target device to access the Coresight DAP on the other. Click CMSIS-DAP to get more information.

This project is an ARM CMSIS-DAP debugger firmware porting on STM32 device. I purchased a minimal system board from taobao.com, cost me about 17 CNY(less than 3$). With this firmware and board, I can debug Cortex M series MCUs from other verdors such as GigaDevice NXP etc. For STM32, maybe ST-Link is a better choice.

For simplicity, I removed rarely used JTAG-Debug, Mass storage, Virtual COM features, kept only the SWD-Debug feature. This leads to smaller code size and gets rid of the trouble of install drivers on Windows.

The SYSCLK of STM32F103C8 is 48M and the code size about 12kB, so the minimal requirement is STM32F102C4.

Usage

First of all, Flash your STM32F103C8 development board with CMSIS-DAP firmware, then your development board becomes a CMSIS-DAP Debugger.

Connect SWCLK, SWDIO, nRESET, GND to your target board, VCC(5V/3.3V) is optional. You can power your target board with CMSIS-DAP.

Port	Function	Note
PB9	SWCLK
PB8	SWDIO
PB7	nRESET	to MCU NRST PIN

Press Alt+F7, click the Debug Tab, select CMSIS-DAP Debugger, and click Settings button.

Check CMSIS-DAP parameters.

Now you can Erase Download Debug your target board.

cmsis-dap's Issues

No Debug Unit Device found

Hi friend. I tried to make my bluePill board as CMSIS-DAP debug programmer for GD chips. I built Keil project. Downloaded it with ST-LINK Utility. And in devices I see the board now as:

And in Options for target project i set this:


It just doesn't see the board as the programmer:

But, sometimes if I don't set SWJ check box, it does show its Serial No and FW. But only once:

Only I close and open again this window, nothing works. Any ideas how to fix that? Thanks for any help.
But as the device Windows 10 says: All works fine.
I use: Keil V 5.36.0.0.
Windows 10.
STM discovery board (ST-Link) as the programmer for blue pill.

Device not showing as a com on windows machines

hey, thanks for the great effort.
i've tried the custom firmware on a linux machine and it is identified and works with no problem on a guest os running in a virtual machine. the problem appeared when i tried to connect to a host machine that is running windows 8.1/10. the device is recognized in HID section and keil doesn't detect it. is there is something i need to do for the device to be recognized correctly?