An FPGA embedded microcontroller

The paper presents the design of an 8-bit RISC microcontroller, which is mainly targeted for performing non-timing crucial functions inside FPGAs. The microcontroller is based on popular Microchip PIC16 microcontrollers family. The main feature of the microcontroller is that it is 4 times faster for regular instructions, and 8 times faster for instructions which modify program counter, than its Microchip archetype clocked at the same frequency. Three versions of the microcontroller instruction cycle structures have been considered and performance tests of the versions have also been carried out. The paper also describes two sample applications which illustrate the usefulness of the microcontroller and show that using the FPGA embedded microcontroller, realization of some functions can be simpler and faster than applying a typical FPGA design flow without the microcontroller. To facilitate frequent exchange of the microcontroller program memory content, specifically at the software developing stage, the downloader module has been proposed to use as well. The downloader allows to directly load the compilers HEX output file to the program memory using a generic serial interface.