AN2077 Datasheet, PDF (1/19 Pages) STMicroelectronics – EEPROM Emulation with STR71x

AN2077
APPLICATION NOTE
EEPROM Emulation with STR71x
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 as-
pects that have to be taken into account.
Substituting external EEPROM with emulated EEPROM from the embedded-Flash of the mi-
crocontroller is a complex development. This application note assumes that readers are al-
ready familiar with the techniques used to secure the content of evolutive information in ex-
ternal 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.
Although this application note is mainly refers to STR710FZ1, STR710FZ2, STR711FR1,
STR711FR2, STR712FR2 and STR712FR2, most of its content is not dependent on the mi-
crocontroller.
AN2077/0705
Rev. 2.0
1/19
1