Gadget Factory Blog
Hello FPGA enthusiasts! Today’s post is a rather special one since it throws open doors to a 32 bit CPU that you can quite simply build with a Spartan 6 FPGA board. Hitachi’s SuperH CPU patents have passed the 25 year mark, and this means that the technology can be reproduced at much lower costs by anyone up to the challenge.
The SuperH technology is a 32-bit RISC architecture ISA from Hitachi that can be used in microcontrollers and microprocessors for embedded applications. Though the CPU can be made extremely efficient in terms of memory usage thanks to the fact that it supports 16 bit instructions, SuperH on your FPGA does have its limitations in the form of MMU and FPU. However this technology can be used to build a super powerful tool either for private projects or for general computing purposes.
With the expiry of the SuperH patents, a new project called J2 has been created, which is the open source platform for SuperH technology. Commonly called the J-Core project, it instructs anyone interested on how to convert an FPGA board into this powerful processor on a very simple way. A Spartan 6 FPGA like the Papilio Pro can be used for this purpose. The Open Source codes are done in VHDL and are all available as open source files in the J-core site. Why don´t you try them on your Papilio board?
The detailed steps that you will need to build your J-Core are given here. The processor runs on Linux. The patents of SuperH regarding MMU and FPU are yet to expire, but once it does, J-Core will be a more powerful platform. The J-Core project is still under evolution and you can closely follow it to make your FPGA J-Core processor stay updated.
By Jim Turley