Unlocking nRF91x1

nRF91 Series Production Programming

Before you begin, complete the steps in Erasing all through CTRL-AP. Then, perform a soft reset using the Control Access Port (CTRL-AP).
  1. Select or connect to the control access port located at index 0x04.
    For more information, see nRF9151 DAP - Debug access port or nRF9161 DAP - Debug access port.
  2. Write 0x00000001 to the RESET register (0x000) of CTRL-AP.
  3. Write 0x00000000 to the RESET register (0x000) of CTRL-AP.
  4. Wait for 20 ms.
  5. Check the Control/Status Word (CSW) register of access port 0.
    If DbgStatus is 1, the access port is enabled.

    If DbgStatus is 0, the access port is not enabled. Do another Erasing all through CTRL-AP, then go back to step 1 and repeat the procedure.

    For more information, see DbgStatus at Arm® Developer CSW register bit assignments.
    Note: Disabling APPROTECT on nRF91x1 devices requires a firmware component. To prevent the device from locking, program the User Information Configuration Registers (UICR) and application firmware to the device before doing a hard reset or power cycle.