59 lines
2.2 KiB
Markdown
59 lines
2.2 KiB
Markdown
# Free-DAP
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This is a free and open implementation of the CMSIS-DAP debugger firmware.
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Only SWD protocol is supported for now. If you have a real need for JTAG support,
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please contact me.
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## Platform requirements
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To create a CMSIS-DAP compliant debugger, your platform must:
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* Implement USB HID device able to receive and send arbitrary reports
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* Provide configuration file dap_config.h with definitions for hardware-dependent calls
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* Call dap_init() at the initialization time
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* Call dap_process_request() for every received request and send the response back
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## Configuration
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For complete list of settings see one of the existing configuration file, they are
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pretty obvious.
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To configure clock frequency you need to specify two parameters:
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* DAP_CONFIG_DELAY_CONSTANT - clock timing constant. This constant can be determined
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by calling dap_clock_test() with varying parameter value and measuring the frequency
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on the SWCLK pin. Delay constant value is the value of the parameter at which
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output frequency equals to 1 kHz.
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* DAP_CONFIG_FAST_CLOCK - threshold for switching to fast clock routines. This value
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defines the frequency, at which more optimal pin manipulation functions are used.
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This is the frequency produced by dap_clock_test(1) on the SWCLK pin.
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You can also measure maximum achievable frequency on your platform by calling dap_clock_test(0).
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Your configuration file will need to define the following pin manipulation functions:
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* DAP_CONFIG_SWCLK_TCK_write()
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* DAP_CONFIG_SWDIO_TMS_write()
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* DAP_CONFIG_TDO_write()
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* DAP_CONFIG_nTRST_write()
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* DAP_CONFIG_nRESET_write()
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* DAP_CONFIG_SWCLK_TCK_read()
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* DAP_CONFIG_SWDIO_TMS_read()
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* DAP_CONFIG_TDI_read()
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* DAP_CONFIG_TDO_read()
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* DAP_CONFIG_nTRST_read()
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* DAP_CONFIG_nRESET_read()
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* DAP_CONFIG_SWCLK_TCK_set()
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* DAP_CONFIG_SWCLK_TCK_clr()
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* DAP_CONFIG_SWDIO_TMS_in()
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* DAP_CONFIG_SWDIO_TMS_out()
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Note that all pin manipulation functions are required even if one of the interfaces (JTAG or SWD) is not enabled.
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Additionally configuration file must contain basic initialization functions:
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* DAP_CONFIG_SETUP()
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* DAP_CONFIG_DISCONNECT()
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* DAP_CONFIG_CONNECT_SWD()
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* DAP_CONFIG_CONNECT_JTAG()
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