Routines for 2-Wire FRAM Using Microchip MCUs

This application note describes bulletproof random write- and read- block routines written specifically for the Ramtron FM24C04 and FM24C16 for Microchip microcontrollers (MCUs) where the processor is the only Master. A third routine is provided to sense the presence of the chip (in case your device is socketed). Although the example here is used on the PIC16C7X, PIC16C8X, and the flash versions of the same devices, these routines are adaptable for almost all PICs as no internal 2-wire (I2C) hardware is used. Micro-Firmware was prompted to write this application note when it became apparent that most application literature ignored Ramtron's devices, which are much easier to implement and devoid of the restrictions imposed by standard EEPROM devices. Due to the fact that Ramtron devices require no write delays, and no restrictions exist on the number of bytes that can be written. You can write the entire FRAM in a single pass! When combined with FRAM's data storage lifetime (I've never met anybody who's seen a bad device), the combination of the Microchip MCU plus FRAM memory is unbeatable.