31.2.22.4 Reset

A user reset during an NVM operation can but does not necessarily cause an error. Atomic operations like single or Quad Write, and page or upper/lower PFM erase finish before reset. The completion of these operations likely delays system exit from reset. Non-atomic operations like SDAL, Row Write, and PFM Erase may early terminate with an error flag set, typically WRERR.

Several SFR bits reset by POR survive a user reset (WDT Reset, RESET pin, GCLK.CTRLA.SWRST, etc). Doing so allows NVM operations to report errors due to reset aborts. This also prevents values like address from changing when cleaning up an aborted operation.