20.6.4.2.1 Procedure for Manual Page Writes (CTRLB.MANW = 1)

The row to be written to must be erased before the write command is given.

1. Write to the page buffer by addressing the NVM main address space directly.
2. Issue a Read-Memory-Barrier from the NVMCTRL AHB0 interface. A single read to AHB0 after writing the whole page buffer.
3. Write the page buffer to memory: CTRL.CMD = 'Write Page' and CMDEX.
4. The READY bit in the INTFLAG register will be low while programming is in progress and access through the AHB will be stalled.