AN2077 Datasheet - STMicroelectronics

INTRODUCTION
External EEPROMs are often used in applications to store data that may be later updated or adjusted. On the other hand, the microcontrollers used in these systems are based more and more on embedded Flash.
The trend to continuously reduce the number of components is forcing designers to look to use Flash memory to emulate EEPROM.
This application note explains the differences between external EEPROMs and embedded-Flash and gives advice on how to substitute external EEPROM to emulated-EEPROM using the on-chip Flash of STR71xF devices.

Although the concept is easy to explain and implement “as is”, there are some embedded aspects that have to be taken into account.
Substituting external EEPROM with emulated EEPROM from the embedded-Flash of the microcontroller is a complex development. This application note assumes that readers are already familiar with the techniques used to secure the content of evolutive information in external EEPROM of embedded applications.

This application note is organized in 4 parts:
– Description of the differences between external EEPROMs and embedded-Flash,
– General description of EEPROM emulation concept,
– Introduction to embedded application aspects,
– Software example.