The 25XXX series serial EEPROMs from Microchip Technology are SPI compatible and have maximum clock frequencies ranging from 3 MHz to 20 MHz. The MSSP module available on many PICmicro microcontrollers provides a very easy-to-use interface for communicating with the 25XXX series devices. The largest benefit of using the MSSP module is that the signal timings are handled through hardware rather than software. This allows the firmware to continue executing while communication is handled in the background. This also means that an understanding of the timing specifications associated with the SPI protocol is not required in order to use the 25XXX series devices in designs.

This application note is intended to serve as a reference for communicating with Microchip’s 25XXX series serial EEPROM devices with the use of the MSSP module featured on many PIC18 family devices. Source code for common data transfer modes is also provided.