Grand Idea Studio



On-chip debug (OCD) interfaces can provide chip-level control of a target device and are a primary vector used by engineers, researchers, and hackers to extract program code or data, modify memory contents, or affect device operation on-the-fly. Depending on the complexity of the target device, manually locating available OCD connections can be a difficult and time consuming task, sometimes requiring physical destruction or modification of the device.

JTAGulator is an open source hardware tool that assists in identifying OCD connections from test points, vias, or component pads on a target device.

Assembled JTAGulators are available from Parallax, Inc. For questions and technical support, please contact Support is only provided for genuine JTAGulators, which are hot pink in color and contain verifiable serial numbers.

This design is distributed under a Creative Commons Attribution-3.0 United States license. The JTAGulator name and logo are registered trademarks of Grand Idea Studio, Inc. The trademarks may not be used on derived works without permission.

Module Highlights:

  • 24 I/O channels with input protection circuitry
  • Adjustable target voltage for level translation: 1.4V to 3.3V
  • Supported target interfaces: JTAG/IEEE 1149.1, UART/asynchronous serial
  • USB interface for direct connection to host computer


Additional Resources:

Acrylic Case:

Sparkle Add-On Board:

Provides neon pink underglow for maximum aesthetics. Connects to the JTAGulator with pogo pins. LEDs will turn on when target voltage (VADJ) is set.


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