an568闪存微控制器的eeprom仿真-AN568分析.PDFVIP

AN568 EEPROM EMULATION F OR F LASH M ICROCONTROLLERS 1. Introduction Non-volatile data storage is an important feature of many embedded systems. Dedicated, byte-writeable EEPROM devices are commonly used in such systems to store calibration constants and other parameters that may need to be updated periodically. These devices are typically accessed by an MCU in the system using a serial bus. This solution requires PCB real estate as well as I/O pins and serial bus resources on the MCU. Some cost efficiencies can be realized by using a small amount of the MCU’s flash memory for the EEPROM storage. This note describes firmware designed to emulate EEPROM storage on Silicon Laboratories’ flash-based C8051Fxxx MCUs. Figure 1 shows a map of the example firmware. The highlighted functions are the interface for the main application code. 2. Key Features  Compile-Time Configurable Size: Between 4 and 255 bytes  Portable: Works across C8051Fxxx device families and popular 8051 compilers  Fault Tolerant: Resistant to corruption from power supply events and errant code  Small Code Footprint: Less than 1 kB for interface functions + minimum two pages of Flash for data storage User Code Fxxx_EEPROM_Interface.c EEPROM_WriteBlock() EEPROM_ReadBlock() copySector() findCurrentSector() getBaseAddress() findNextSector() Fxxx_Flash_Interface.c FLASH_WriteErase() FLASH_BlankCheck() FLASH_Read() Figure 1. EEPROM Emulation Firmware Rev. 0.1 12/10 Copyright © 2010 by Silicon Laboratories AN568 AN568 3. Basic Operation A very simple example project and wrapper code is inclu