STMicroelectronics AN1502 Application Note Emulated Data EEPROM with ST7 HDFlash Memory

About this manual

When a data EEPROM is not available in an ST7 device, it can be emulated by the HDFlash memory with specific restrictions. This document details the principles of this emulation for the ST72F521 device and explains the necessary programming voltage requirements.

Two implementation methods are described: one limiting byte values to 00h..FEh and another supporting all values from 00h..FFh by using two memory locations per byte. The note also outlines restrictions, such as the limited number of write/erase cycles and the requirement to disable RASS protection.

What's inside

• Introduction
• Principle
• Restrictions
• Advantage
• Assembler Program Example

Frequently asked questions

What voltage must be provided on the application board for HDFlash programming?

The 12-volt programming voltage must be provided on the application board.

In which sectors can emulated data EEPROM be located?

Emulated data EEPROM must be located in sector 1 or 2 because sector 0 is write protected.

What happens to the protection against unintentional access when using Embedded Commands?

The protection against unintentional access to the HDFlash control register is no longer available.