13.3 Lock and Write Restrictions

The LOCK bit (PCLKCON[8]) may be set in software to block writes to certain registers. For more information, refer to “High-Resolution PWM with Fine Edge Placement” (www.microchip.com/DS70005320) in the “dsPIC33/PIC24 Family Reference Manual.”

The following lock/unlock sequence is required to set or clear the LOCK bit.

1. Write 0x55 to NVMKEY.
2. Write 0xAA to NVMKEY.
3. Clear (or set) the LOCK bit (PCLKCON[8]) as a single operation.

In general, modifications to configuration controls should not be done while the module is running, as indicated by the ON bit (PGxCONL[15]) being set.