The Control Access Port (CTRL-AP) is a custom access port that enables control of the device even if other access ports in the Debug Access Port (DAP) are disabled by Access Port Protection (APPROTECT).
If access port protection has been enabled in the APPROTECT register (0x00FF8000)
of the
User Information Configuration Registers (UICR), the debugger's read/write access to all CPU
registers and memory mapped addresses is blocked.
For more information about CTRL-AP,
see nRF9160 CTRL-AP - Control access port.
Use the standard
Serial Wire Debug (SWD)
Arm®
CoreSight™ DAP protocol to
check if APPROTECT is enabled.
-
Select or connect to the control access port.
-
Read the APPROTECT.STATUS register (0x00C) of the CTRL-AP.
If the bit at position 1 of this register is 0, APPROTECT is
enabled.
If the bit at position 1 of this register is 1, APPROTECT is
disabled.
-
Read the ERASEPROTECT.STATUS (0x018) of the CTRL-AP.
If ERASEPROTECT is set, it can be disabled if the installed firmware and the
debugger both write the same non-zero 32-bit KEY value to ERASPROTECT.DISABLE
(0x01C).
Note: If APPROTECT and ERASEPROTECT are enabled and the device does
not have firmware that allows disabling ERASEPROTECT, the device is locked
and cannot be recovered.
-
Go to Erasing all.
If the least significant bit of this register is
1, access port protection is disabled. Go to
Halting the CPU.