24.3.1 Control Register Lock
Under normal operation, writing to the PMDx registers is not allowed. Attempted writes appear to execute normally, but the contents of the registers remain unchanged. To change these registers, they must be unlocked in the hardware. The CFGCON0.PMDLOCK Configuration bit controls the register lock. Setting CFGCON0.PMDLOCK prevents writes to the control registers, and clearing CFGCON0.PMDLOCK allows write operation.