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xr16vx in JHDL v1.0 is online

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  • Mike Butts
    I ve polished off the xr16vx microcontroller in JHDL, and posted it, along with tools, tests and documentation:
    Message 1 of 1 , Jun 30, 2001
      I've polished off the xr16vx microcontroller in JHDL, and
      posted it, along with tools, tests and documentation:
      http://www.easystreet.com/~mbutts/xr16vx_jhdl.html

      xr16vx is a 16-bit microcontroller design for FPGAs, which I've
      released as open source programming under the GPL. Including
      memory, serial and parallel ports and a timer, it fits in only
      29% of a Xilinx Spartan-II XC2S100-5, at up to 39 MHz.

      xr16vxcpu implements the xr16 16-bit RISC instruction set
      architecture of Jan Gray:
      http://www.fpgacpu.org/xsoc/README.html
      Jan's xsoc package includes an assembler and ANSI C compiler
      for xr16 based on lcc. My xr16vxcpu runs at one cycle per
      instruction, except taken branches and loads used next cycle.
      It takes advantage of the dual-ported BlockRAM to fetch instructions
      and data in parallel.

      xr16vx is written in JHDL, a set of Java classes and tools for FPGA
      design developed at BYU:
      http://www.jhdl.org/release-latest/docs/overview/intro.html
      In JHDL you do register-level design but without synthesis.
      I've found JHDL a very satisfying development environment, and am
      getting slightly better speed and area than I got in Verilog with
      FPGA Express.

      Since the xr16vx microcontroller is completely contained in the
      FPGA, you can write a C program for xr16vx, init the BlockRAMs
      with it in the EDIF file, and thus have the application built into
      the bitstream, executing at power-up. I include some tools I wrote
      to make doing this easy.

      Thanks to Jan Gray's xsoc, BYU's JHDL and Xilinx WebPACK ISE, the
      entire design flow for xr16vx is available on the Web at no cost.
      I've developed xr16vx myself on my own time, because I love FPGAs
      and I love CPU design. I hope students, experimenters, and anyone
      on a limited budget will find xr16vx useful.

      --Mike
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