This repo contains a simple functionality, GPIOs controlled by JTAG, and uses that to illustrate how we can use different techniques to control these GPIOs through various methods and for various platforms.

For more info, check out my blog post that goes along with this: JTAG for FPGAs - Part 1: JTAG_GPIO

• ./rtl

  Design example with JTAG GPIOs that uses either an instantiated generic JTAG TAP or ties in to an Intel/Altera virtual JTAG.

• ./tb

  Simulation testbench

• ./altera

  Quartus build files for an EP2C5T144 FPGA board.

• ,.ice40

  ICE40 build files for a BlackIce-II FPGA board

• ./openocd/basic

  Example on how to control the generic JTAG TAP with OpenOCD and TCL commands.

• ./openocd/target

  Example on how to control the generic JTAG TAP with OpenOCD and a Python script

All code is released under an Unlicense license, except the code that was not written by me:

• rtl/jtag_tap_generic.v and rtl/jtag_tap_defines.v are released un LGPL (see top of file.)
• rtl/blackbox/sld_virtual_jtag.v is released under some Altera licence.