The purpose of this application note is to offer the designer a set of examples for the read and write functions for using the Microchip SPI serial SRAM.

Microchip’s serial SRAM product line represents a new way to add additional RAM to an application. With the small 8-pin packages and the SPI interface, these devices give designers added system flexibility. The 23XXXX series of serial SRAM devices from Microchip Technology support a half-duplex protocol that functions on a master-slave paradigm that is ideally suited to data stream applications.

The bus is controlled by the Microcontroller (master), which accesses the 23XXXX using the MSSP peripheral built into the MCU configured for SPI operation. The MSSP peripheral can support throughput up to 5 or 8 MHz depending upon the device family of PIC16/18 MCU Selected. Communication can be paused using the HOLD pin.

The code was tested using the 23K256 SRAM mounted on the general purpose section of the PICDEM™ 2 Plus development board. The MSSP module is configured for SPI Master mode with a clock frequency of 5 MHz. The code is compatible with the PIC16F/18F families of MCUs with the MSSP module.