29.2 Module Overview

SAM device embeds a separate read while write EEPROM emulation (RWWEE) array that can be programmed while the main array is not blocked. To use RWWEE memory, data must be written as a number of physical memory pages (of several bytes each) rather than being individually byte addressable, and entire rows of RWWEE must be erased before new data may be stored. To help abstract these characteristics away from the user application an emulation scheme is implemented to present a more user-friendly API for data storage and retrieval.

This module provides a RWW EEPROM emulation layer on top of the device's internal NVM controller, to provide a standard interface for the reading and writing of non-volatile configuration data. This data is placed into the RWW EEPROM emulated section. Emulated EEPROM is exempt from the usual device NVM region lock bits, so that it may be read from or written to at any point in the user application.

There are many different algorithms that may be employed for EEPROM emulation, to tune the write and read latencies, RAM usage, wear levelling, and other characteristics. As a result, multiple different emulator schemes may be implemented, so that the most appropriate scheme for a specific application's requirements may be used.