Dual I²C and SPI Slave Core for FPGA and ASIC Implementations

The I2C/SPI Verilog core consists of a combined register transfer logic (RTL) Verilog code for a general-purpose I2C and serial-to-parallel interface (SPI) slave for implementations targeting field programmable gate arrays (FPGAs) and application specific integrated circuits (ASICs). The core was developed as part of the radiation hardened digital-to-analog converters’ 10-bit (RH-DAC10) and 12-bit (RH-DAC12) ASICs. The core contains both an I2C and SPI slave cores that share all inputs/outputs, and is selectable by setting a single input. The I2C portion uses an asynchronous design and does not require a continuous clock to operate, thus reducing the dynamic power consumption. The core serves as a baseline that can be tailored to any application requiring I2C and SPI slave interfaces. The core has been implemented and verified in both a commercial FPGA and a custom, radiation-hardened ASIC in a commercial CMOS (complementary metal-oxide semiconductor) 0.25-μm process, where the I2C and SPI were tested at 1 MHz and 50 MHz, respectively.