Optimizing the use of an SPI Flash PROM in Microblaze-Based Embedded Systems

This paper aims to simplify FPGA designs that incorporate Embedded Software Systems using a soft core Processor. It describes a simple solution to reduce the need of multiple non-volatile memory devices by using one SPI (Serial Peripheral Interface) Flash PROM for FPGA configuration data, software code (Processor applications), and miscellaneous user data. We have thus developed a design based on a MicroBlaze soft processor implemented on a Xilinx Spartan-6 FPGA SP605 Evaluation Kit. The hardware architecture with SPI flash was designed using the Xilinx Platform Studio (XPS) and the software applications, including the bootloader, was developed with Xilinx Software Development Kit (SDK). ISE Design Tools prepared by Xilinx Company, is employed to create the files used to program flash memory which are SREC (S-record) file associated with software code, Hexadecimal file for user data, and bootloader file to configure the FPGA and allows software applications stored in flash memory to be executed when the system is powered on. Reading access to the SPI Flash memory is simplified by the use of Xilinx In-System Flash (ISF) library. Keywords—Microblaze; ISF; Bootloader; SREC; Configuration; Bitstream SPI Flash