rtt studio用DAP下载不成功怎么解决？

rtt用DAP下载程序到野火指南者开发板不能成功。
MCU是STM32F103，DAP下载器。下载方式设置就是DAP，速度根据相似的帖子改成最慢了。

• done!
  
• 
  
• 开始下载程序：2021-05-19 20:12:20
  
• E:RT-ThreadStudio>cd /d E:RT-ThreadStudiorepoExtractDebugger_Support_PackagesRealThreadPyOCD�.1.1
  
• E:RT-ThreadStudiorepoExtractDebugger_Support_PackagesRealThreadPyOCD�.1.1>pyocd.exe flash --target=STM32F103VE --erase=auto  --frequency=1000000 C:UserswhiskyDesktoprttccDebugrtthread.bin
  
• 0001553:CRItiCAL:__main__:No ACK received
  
• Traceback (most recent call last):
  
•   File "pyocdprobecmsis_dap_probe.py", line 249, in read_dp
  
•   File "pyocdprobepydapaccessdap_access_cmsis_dap.py", line 836, in read_reg
  
•   File "pyocdprobepydapaccessdap_access_cmsis_dap.py", line 830, in read_reg_cb
  
•   File "pyocdprobepydapaccessdap_access_cmsis_dap.py", line 143, in get_result
  
•   File "pyocdutilityconcurrency.py", line 28, in _locking
  
•   File "pyocdprobepydapaccessdap_access_cmsis_dap.py", line 667, in flush
  
•   File "pyocdutilityconcurrency.py", line 28, in _locking
  
•   File "pyocdprobepydapaccessdap_access_cmsis_dap.py", line 915, in _read_packet
  
•   File "pyocdprobepydapaccessdap_access_cmsis_dap.py", line 449, in decode_data
  
•   File "pyocdprobepydapaccessdap_access_cmsis_dap.py", line 418, in _decode_transfer_block_data
  
•   File "pyocdprobepydapaccessdap_access_cmsis_dap.py", line 341, in _check_response
  
• pyocd.probe.pydapaccess.dap_access_api.DAPAccessIntf.TransferError: No ACK received
  
• The above exception was the direct cause of the following exception:
  
• Traceback (most recent call last):
  
•   File "pyocd__main__.py", line 362, in run
  
•   File "pyocd__main__.py", line 520, in do_flash
  
•   File "pyocdcoresession.py", line 302, in __enter__
  
•   File "pyocdcoresession.py", line 420, in open
  
•   File "pyocdboardboard.py", line 85, in init
  
•   File "pyocdcorecoresight_target.py", line 160, in init
  
•   File "pyocdutilitysequencer.py", line 213, in invoke
  
•   File "pyocdutilitysequencer.py", line 208, in invoke
  
•   File "pyocdcoresightdap.py", line 303, in _connect
  
•   File "pyocdcoresightdap.py", line 167, in connect
  
•   File "pyocdcoresightdap.py", line 194, in read_idr
  
•   File "pyocdprobecmsis_dap_probe.py", line 251, in read_dp
  
•   File "", line 3, in raise_from
  
• pyocd.core.exceptions.TransferError: No ACK received
  
• 执行完毕, 耗时：4395ms.