101 lines
3.7 KiB
Markdown
101 lines
3.7 KiB
Markdown
# Free-DAP
|
|
|
|
This is a free and open implementation of the CMSIS-DAP debugger firmware.
|
|
|
|
Both SWD and JTAG protocols are supported. However JTAG was not well tested due to lack of
|
|
good targets. If you have any issues with it - let me know and I'll try to help.
|
|
|
|
## Platform requirements
|
|
|
|
To create a CMSIS-DAP compliant debugger, your platform must:
|
|
* Implement USB HID (and raw bulk for CMSIS-DAP v2) device able to receive and send arbitrary payloads
|
|
* Provide configuration file dap_config.h with definitions for hardware-dependent calls
|
|
* Call dap_init() at the initialization time
|
|
* Call dap_process_request() for every received request and send the response back
|
|
|
|
## CMSIS-DAP version support
|
|
|
|
Free-DAP library itself is protocol agnostic and implementation of the specific version
|
|
of the CMSIS-DAP protocol (v1 or v2) is up to the individual platforms.
|
|
|
|
Currently RP2040, SAM D11 and SAM D21 implementaitons were updated to support CMSIS-DAP v2.
|
|
Other platforms would be updated if requested or needed by me.
|
|
|
|
## Configuration
|
|
|
|
For complete list of settings see one of the existing configuration file, they are
|
|
pretty obvious.
|
|
|
|
To configure clock frequency you need to specify two parameters:
|
|
* DAP_CONFIG_DELAY_CONSTANT - clock timing constant. This constant can be determined
|
|
by calling dap_clock_test() with varying parameter value and measuring the frequency
|
|
on the SWCLK pin. Delay constant value is the value of the parameter at which
|
|
output frequency equals to 1 kHz.
|
|
* DAP_CONFIG_FAST_CLOCK - threshold for switching to fast clock routines. This value
|
|
defines the frequency, at which more optimal pin manipulation functions are used.
|
|
This is the frequency produced by dap_clock_test(1) on the SWCLK pin.
|
|
You can also measure maximum achievable frequency on your platform by calling dap_clock_test(0).
|
|
|
|
Your configuration file will need to define the following pin manipulation functions:
|
|
|
|
* DAP_CONFIG_SWCLK_TCK_write()
|
|
* DAP_CONFIG_SWDIO_TMS_write()
|
|
* DAP_CONFIG_TDO_write()
|
|
* DAP_CONFIG_nTRST_write()
|
|
* DAP_CONFIG_nRESET_write()
|
|
* DAP_CONFIG_SWCLK_TCK_read()
|
|
* DAP_CONFIG_SWDIO_TMS_read()
|
|
* DAP_CONFIG_TDI_read()
|
|
* DAP_CONFIG_TDO_read()
|
|
* DAP_CONFIG_nTRST_read()
|
|
* DAP_CONFIG_nRESET_read()
|
|
* DAP_CONFIG_SWCLK_TCK_set()
|
|
* DAP_CONFIG_SWCLK_TCK_clr()
|
|
* DAP_CONFIG_SWDIO_TMS_in()
|
|
* DAP_CONFIG_SWDIO_TMS_out()
|
|
|
|
Note that all pin manipulation functions are required even if one of the interfaces (JTAG or SWD) is not enabled.
|
|
|
|
Additionally configuration file must provide basic initialization and control functions:
|
|
|
|
* DAP_CONFIG_SETUP()
|
|
* DAP_CONFIG_DISCONNECT()
|
|
* DAP_CONFIG_CONNECT_SWD()
|
|
* DAP_CONFIG_CONNECT_JTAG()
|
|
* DAP_CONFIG_LED()
|
|
* DAP_CONFIG_DELAY()
|
|
|
|
## Tools
|
|
|
|
A complete RP2040 build requres bin2uf2 utility to generate UF2 file suitable for the RP2040 MSC bootloader.
|
|
This utility can be downloded [here](https://github.com/ataradov/tools/tree/master/bin2uf2).
|
|
|
|
## Binaries
|
|
|
|
Generally there are no pre-built binaries due to effort required to maintain
|
|
them and low potential benefit because of custom hardware requirement.
|
|
|
|
For RP2040 and Raspberry Pi Pico board specifically there is a binary, since
|
|
it is a standard and a widely available board that has a nonvolatile bootloader.
|
|
|
|
The UF2 file is located [here](bin/free_dap_rp2040.uf2). Simply boot into
|
|
a BootROM MSC mode and copy that file to the drive.
|
|
|
|
I will try to do my best to keep this binary in sync with the code updates, but
|
|
it is a manual process, so I may forget. Let me know if you have any issues.
|
|
|
|
The pins used are as follows:
|
|
|
|
| GPIO | Function |
|
|
|:---:|:---|
|
|
| 11 | SWCLK/TCK |
|
|
| 12 | SWDIO/TMS |
|
|
| 13 | TDI |
|
|
| 14 | TDO |
|
|
| 15 | nRESET |
|
|
| 0 | VCP TX |
|
|
| 1 | VCP RX |
|
|
| 2 | VCP Status |
|
|
| 25 (LED) | DAP Status |
|
|
|