9.5.7.1 Sequence for Write Operation to Configuration Change Protected I/O Registers
In order to write to registers protected by CCP, these steps are required:
- The software writes the signature that enables change of protected I/O registers to the CCP bit field in the CPU.CCP register.
- Within four instructions, the software
must write the appropriate data to the protected register.
Most protected registers also contain a Write Enable/Change Enable/Lock bit. This bit must be written to ‘
1
’ in the same operation as the data are written.The protected change is immediately disabled if the CPU performs write operations to the I/O register or data memory, if load or store accesses to Flash, NVMCTRL, or EEPROM are conducted, or if the SLEEP instruction is executed.