Software Aided Wishbone Extension for Xilinx (R) PicoBlaze (TM) :: Overview

Project maintainers


Name: wb4pb
Created: Jan 5, 2010
Updated: Apr 22, 2011
SVN Updated: Aug 28, 2013
SVN: Browse
Latest version: download (might take a bit to start...)
Statistics: View
Bugs: 0 reported / 0 solved
Star0you like it: star it!

Other project properties

Language:Verilog & VHDL
Development status:Stable
Additional info:Design done, FPGA proven, Specification done
WishBone compliant: No
WishBone version: n/a
License: BSD


This project provides interface logic and assembler routines, giving PicoBlaze (TM) embedded soft-uC the ability to access wishbone systems or slave cores as an 8-bit master device. There is no native hardware handshake mechanism at PicoBlaze (TM) ports, so wishbone wait-state recognition is done by software polling. Some standard wishbone slave peripherals like GPIO and UART are included as well.


  • Multi HDL language implementation VHDL and Verilog (R)
  • Assembler subroutines
  • Simulation testbench and command file
  • Notepad++ custom syntax highlighter for assembler
  • Synthesizable GPIO example
  • Synthesizable UART example, using Xilinx (R) UART macros together with a wishbone slave wrapper
  • Baud rate calculation script
  • Implementation files for low cost AVNET (R) Spartan(R)-3A Evaluation Kit using Xilinx ISE (R) 13.1

Getting Started

  1. Prerequisites: Xilinx ISE (R) and ModelSim Xilinx Edition III (R)
  2. Download wb4pb sources and be sure to keep directory structure!
  3. Download PicoBlaze (TM) from Xilinx (R) (registration required)
  4. Copy kcpsm3.v and kcpsm3.vhd to rtl directory
  5. Open in a text editor and customize "set wd ..." and "set isVHDL ..." lines
  6. Start ModelSim (R) and execute DO-File (Menu->Tools->TCL->Execute Macro...)

Synthesis Results

xc3s400a-4ft256 device using Xilinx ISE (R) 13.1 with default settings

GPIO example VHDLGPIO example Verilog (R)UART example VHDLUART example Verilog (R)
max. frequency97.220MHz102.082MHz101.647MHz100.553MHz
clock nets1111
slice utilization3%3%5%5%
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