The control access port (CTRL-AP) is a custom access port that enables control of the device when other access ports (AP) have been disabled by the access port protection.
For an overview of the other debug access ports, see DAP.
Access port protection (APPROTECT) blocks the debugger from accessing the AHB-AP and prevents read and write access to all CPU registers and memory-mapped addresses.
Erase protection (ERASEPROTECT) protects the entire non-volatile memory, and UICR from being erased. Erase protection is enabled through UICR and disabled through cooperation between the firmware and debugger. For more information about disabling erase protection, see Erase protection.
- Reset the device
- Erase all
- Mailbox interface
- INFO.PARTNO and INFO.HWREVISION registers
- Peripheral registers – Accessed by a CPU using the APB interface
- Debugger registers – Accessed by an external debugger using the CTRL-AP interface