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Hello,
Once the lifecycle stage is set to SECURE, is it possible to go from a DAP lock state to a DAP unlock state using the EFUSE_DATA_SECURE_ACCESS_RESTRICT0 register?
If not, is there any way to unlock the DAP once it has been locked in any given lifecycle stage?
Thank you,
Xavier
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Hello Xavier,
Answers inline.
When in Secure w/ Debug Lifecycle mode, will the DAP access be enabled even if the EFUSE_DATA_SECURE_ACCESS_RESTRICT0 register is set to disable the DAP access?
Yes, that's right. In Secure w/ Debug mode, the normal access restrictions will apply. EFUSE_DATA_SECURE_ACCESS_RESTRICT0 will only come into effect if you transition to Secure mode from Normal mode. It does not have a role to play in Secure w/ Debug mode.
Is it possible to lock/unlock the DAP in Normal Lifecycle mode? If so, could you advise on the procedure to follow?
Yes, it is. Please refer to the following thread: Is it possible to prevent user to trace through SWD/JTAG?
Regards,
Dheeraj
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Hello Xavier,
No, this is not possible. Blowing the EFuse is an irreversible process. So, based on the EFUSE_DATA_SECURE_ACCESS_RESTRICT0 register setting, it is going to blow the EFuses accordingly when the lifecycle is changed to SECURE and you can't go back to a lower protection setting.
Hence, during development, it is recommended to test your designs using NORMAL and Secure w/ Debug Lifecycle modes. Secure w/ Debug allows DAP access.
For more information refer:
Hope this answers your query
Regards,
Dheeraj
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Hi Dheeraj,
Thank you for your reply!
First follow-up question:
When in Secure w/ Debug Lifecycle mode, will the DAP access be enabled even if the EFUSE_DATA_SECURE_ACCESS_RESTRICT0 register is set to disable the DAP access?
Second follow-up question:
Is it possible to lock/unlock the DAP in Normal Lifecycle mode? If so, could you advise on the procedure to follow?
From the DAP Security section of the PSoC 6 programming manual: "The second bit, CPUSS_DP_CTL.xxx_DISABLE, can be set during boot, before the debugger can connect, based on eFuse settings for SECURE or DEAD life-cycle stage or based on NAR settings in Supervisory flash for NORMAL life-cycle."
Thank you very much,
Xavier
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Hello Xavier,
Answers inline.
When in Secure w/ Debug Lifecycle mode, will the DAP access be enabled even if the EFUSE_DATA_SECURE_ACCESS_RESTRICT0 register is set to disable the DAP access?
Yes, that's right. In Secure w/ Debug mode, the normal access restrictions will apply. EFUSE_DATA_SECURE_ACCESS_RESTRICT0 will only come into effect if you transition to Secure mode from Normal mode. It does not have a role to play in Secure w/ Debug mode.
Is it possible to lock/unlock the DAP in Normal Lifecycle mode? If so, could you advise on the procedure to follow?
Yes, it is. Please refer to the following thread: Is it possible to prevent user to trace through SWD/JTAG?
Regards,
Dheeraj