SWRU626 December 2025 CC3501E , CC3551E
The DAP bridge serves as a connection between Serial Wire (SW) Debug Port and AHB-AP Access Port. There are 4 debug authentication control signals driven from DEBUGSS to CPUSS:
DBGEN (Invasive debug enable)
NIDEN (Non-Invasive debug enable)
SPNIDEN (Secure Peripheral Non-Invasive Debug Enable)
SPIDEN (Secure Peripheral Invasive Debug Enable)
SPNIDEN and SPIDEN can be overwritten by CPUSS by writing to the DAUTHCTRL MMR of M33.
For invasive debug enable, DBGEN must be set. For non-invasive debug enable, NIDEN must be set.
For TPIU to function, NIDEN must be set. Only single wire trace is enabled for TPIU. 4 wire trace is not supported.
| DBGEN | SPIDEN | Invasive Debug Status | Invasive debug permitted states |
|---|---|---|---|
| LOW | X | DISABLED | None |
| HIGH | LOW | ENABLED | All None Secure States |
| HIGH | HIGH | ENABLED | All States |
| NIDEN | SPNIDEN | States in which non-invasive debug is permitted | |
|---|---|---|---|
| LOW | X | None | |
| HIGH | LOW | All Non Secure States | |
| HIGH | HIGH | All States | |