MorriganR's JTAG Knock-Knock Turns an Arduino Nano Into a Tool for Tracing FPGA Pinouts
Designed to use minimal additional components, the JTAG Knock-Knock assists with documenting an unknown FPGA board's pinout.
Pseudonymous maker MorriganR has created a device, based on an Arduino Nano, designed to make tracing the pinout of an unknown field-programmable gate array (FPGA) board as easy as possible: the JTAG Knock-Knock.
"In my opinion, the most appropriate name for this project is JTAG Hello World because it implements the IEEE 1149.1 basic standard from which the minimum set of functions was used," writes Morrigan. "JTAG was implemented using bit-banging technology. This allowed the entire project to be executed on an Arduino board with a minimal number of additional components."
Those minimal components: a series of resistors, a pogo pin, headers, and cable originally used for earphones. With those, and some clever code, the JTAG Knock-Knock makes it possible to trace the pinout of a novel FPGA board quickly and easily.
"The main goal is to go through all the pins on the board, in order to find a matching pin of FPGA," Morrigan explains. "Entering monitor mode with command 'm' and connecting a special probe pin to external one gives us information about bits on the terminal, which we find in the BSDL file and write down information about pin. After a few hours this process is finally over and as a result we get the file with pinout."
Morrigan has published a build guide and instructions for use on the project's page, while the Arduino source code is available under an unspecified licence on GitHub.
