After cortex-m55 uses swd to connect, it fails to send selectinterface jtag

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    • After cortex-m55 uses swd to connect, it fails to send selectinterface jtag

      As the title says, swd2jtag fails. I captured the waveform and found that jlink sent the command of Switching from SWD to JTAG operation: 0x3CE7, but my cortex-m55 does not support this switching command. It only supports switching in dormant operation mode, so the command is not responded. jlink reports an error after judging that TDO is always high. Here, the dormant switching mode should be added and tried again, and then an error is reported again. In fact, when jtag switches to swd, after the 0x79E7 command fails, jlink will send the dormant switching sequence to try to connect again. I hope that dormant switching support will also be added when swd switches to jtag. Thank you



      //The following is the waveform file captured by the logic analyzer. You can use Dsview software to open and view it.
      Download address: https://www.dreamsourcelab.com/download/

      cortex-m55-swd2jtag-FAILED.7z

      The post was edited 1 time, last by Eclipse ().

    • Hello,

      Switching the interface to JTAG in dormant mode is already supported however the corresponding command was previously undocumented.

      I have added the documentation for this command to our knowledge base. For more information, please refer to:
      kb.segger.com/J-Link_Command_Strings#SetDormantModeHandling

      Best regards,
      Simon
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    • SEGGER - Simon wrote:

      Hello,

      Switching the interface to JTAG in dormant mode is already supported however the corresponding command was previously undocumented.

      I have added the documentation for this command to our knowledge base. For more information, please refer to:
      kb.segger.com/J-Link_Command_Strings#SetDormantModeHandling

      Best regards,
      Simon

      Thanks for your reply

      1. After using the command: exec SetDormantModeHandling=1, the switch from swd to jtag was successful

      2. Can this function be integrated into the "selectinterface jtag" function, that is, automatically send the dormant sequence to switch to jtag after the simple sequence switch fails

      Thanks again