JTAGulator alternative for RP2040 microcontroller based development boards including RPi Pico.

Connect the RP2040 microcontroller based development board running blueTag to your computer using USB cable. Connect the development board's GPIO pins (GPIO0-GPIO15 so 16 channels in all) to your target's testpoints on the PCB. Connect the development board's "GND" pin to target's "GND". Connect to your RP2040 using a terminal emulator. blueTag supports auto-baudrate detection so you should not have to perform any additional settings. Press any key in the terminal emulator program to start using blueTag. The firmware methodically pokes at all of the connected lines to figure out what kind of interface it is (JTAG, I2C, SPI, etc) and which line is hooked to which pin of that interface for you.

Given an Arduino compatible microcontroller or Raspberry PI (experimental), JTAGenum scans pins[] for basic JTAG functionality and can be used to enumerate the Instruction Register for undocumented instructions. Props to JTAG scanner and Arduinull which came before JTAGenum and forwhich much of the code and logic is based on.