Hello, everyone! Welcome to this blog where we delve into the motivation and process of building a **JTAGulator**, an invaluable tool for test engineers, developers, and hackers alike. If you’re looking to identify on-chip debugging interfaces such as JTAG, UART, or SWD, this blog is for you! > **Note**: Price mentioned includes India import and custom taxes; we ordered in bulk.

### Motivation and Introduction to JTAGulator The idea for this blog came when we realized how challenging it was to source a JTAGulator within India. **JTAGulator**, an open-source tool by **Joey Grand** from Grand Idea Studio, is essential for identifying various interfaces on embedded devices. ### Protocols Supported - JTAG - UART - SWD - GPIO logic analysis The tool lets you configure aspects like input-output voltage, making it versatile. Despite being launched at DEFCON 21 in **2013**, it remains a **reliable and popular** tool among hackers. Given its rarity in stock, we decided to **build our own**! ### Starting the Build: The PCB We started by downloading the **Gerber file** from Grand Idea Studio’s website. As per the **Creative Commons Attribution 3.0 Licence**, full credit goes to **Joey Grand** and **Grand Idea Studio**. We uploaded the Gerber file to a local PCB manufacturer. **Cost**: ~350 INR (~4.5 USD) per PCB. **Download**: [JTAGulator Gerber Files](https://grandideastudio.com/portfolio/jtagulator/)

### Gathering Components: Bill of Materials (BOM) The **Bill of Materials** (BOM), available on Grand Idea Studio’s site, includes: - **Quantity** - **Reference** (e.g., C for capacitor, D for diode) - **Manufacturer & Part Number** - **Distributor** (e.g., DigiKey, Mouser) > Tip: Some countries enforce import regulations; prepare for **customs clearance** accordingly.

### Assembly and Soldering With the PCB and components ready, we used the following tools for assembly: - Solder Paste (Mechanic brand) - Brush and Blade Set - Soldering Station & BGA Rework Station - Tweezers & PCB Holder - Stereo Microscope for precision soldering - Multimeter for continuity and voltage checks

Placement of **SMD components**, especially those with polarity (e.g., tantalum capacitors), required precision. Capacitors, resistors, diodes, and ICs were placed as per the BOM.

### Soldering Steps and Troubleshooting After placement, we: - Used a **multimeter** to test for shorts - Used **isopropyl alcohol** to clean excess flux > Common issue: Shorts around ICs can prevent USB detection.

### Final Assembly and Testing We followed the **[test procedure](https://grandideastudio.com/media/jtagulator_testproc.pdf)** from Grand Idea Studio. - Checked USB port recognition - Flashed firmware using **Parallax Propeller Tool** ### Powering Up and Validation We connected to the JTAGulator via **serial console** (e.g., GTKTerm) at **115200 baud**. On success, the device displays a welcome message and the **LED turns green**. [Download Propeller Tool v1.3.2](https://grandideastudio.com/media/P8X32A-Setup-Propeller-Tool-v1.3.2.zip)

### Final Cost Estimate | Component | Cost (INR) | |-----------|------------| | PCB | 350 | | Components (imported) | ~4800 | | Assembly Tools/Extras | ~350 | | **Total** | **~5500 INR (~66 USD)** | ### Conclusion With patience and precision, building a **JTAGulator** can be **rewarding and cost-effective**. This DIY approach not only saves money but offers **deep insight** into hardware debugging. > Embrace the hacker’s way - **bruteforce those pins and own the board**. **Happy Hacking! 🎉**

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Can't buy a JTAGulator? Then build it – DIY under $75

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Can't buy a JTAGulator? Then build it – DIY under $75