Hard Processor System Technical Reference Manual: Agilex™ 5 SoCs

ID 814346
Date 7/19/2024
Public

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15.5.1.4.2. Debug Reset Request via DAP SWJ-DP

In order to allow an external debugger easy access to reset the CoreSight* subsystem, the HPS uses the DAP’s CDBGRSTREQ/ACK. This allows the debugger to reset the CoreSight* network from the JTAG TCLK domain using the DAP’s built-in debug reset request without having to know the memory mapped location of debug reset within the HPS reset manager.

Use DAP SWJ-DP’s CDBGRSTREQ/ACK signals:

  • The DAP’s CDBGRSTREQ signal is set by an external debugger. This signal is then driven by a register in the TCLK domain and is synchronized within the reset manager and used to start a debug reset sequence.
  • The external debugger can then poll the DAP’s CDBGRSTACK register to detect when the debug reset sequence has completed. The DAP’s CDBGRSTACK input is set by the reset manager to acknowledge the debug reset is complete.
  • Once the DAP’s CDBGRSTACK signal is asserted to indicate debug reset completion, the external debugger then clears the DAP’s CDBGRSTREQ. Once the DAP CDBGRSTREQ signal is cleared, the reset manager then clears the CDBGRSTACK.