Hit by a Key Component Shortage, PrintNanny's Leigh Johnson Learns PCB Design and Fabrication

Leigh Johnson and Jason Zaman, creators of the PrintNanny machine learning system for automatically detecting 3D print failures, found an important piece of the hardware stack hit by component shortages — so learned how to make a replacement.

"I desperately needed a Tizen SDWire board to automate smoke tests for PrintNanny OS, a Linux distribution I created to manage 3D printers using a Raspberry Pi," Johnson explains. "The SDWire board would allow me to re-image the Raspberry Pi's SD card (without physically removing the SD card from the Pi). Unfortunately, SDWire boards were completely sold-out. Everywhere! I was willing to pay a huge markup for just one of these gosh-darn boards … but no one could sell me one."

It's a common story in these days of ongoing supply chain issues, and typically means shifting to an alternative device — but Johnson opted for a different approach, taking the open source SDWire design and learning how to recreate it using available components. "The SDWire PCB design is open source, so surely some enterprising individuals would step up and meet the market demand," Johnson explains. "Well, it turns out those enterprising individuals are me and my partner, Jason Zaman.

"A few years ago, it would've been straightforward to reproduce an open source PCB design by sending the board's Gerber files (a type of layered export) directly to a manufacturer like JLPCB. In today's landscape of constrained electronics supply, even basic components in PCB designs are unavailable. For example, the original SDWire design uses a 2kB EEPROM memory chip. Texas Instruments components are more readily available in the current United States market than imported equivalents. However, Texas Instruments is not manufacturing 2kB EEPROM and imported 2kB stock is limited."

Leaning on Zaman's experience as an electrical engineering and computer science major, Johnson used KiCad to modify the SDWire design to accept the differing footprints of TI's equivalent and more readily-available parts — which, coupled with some software changes, provided a compatible alternative to the original Tizen SDWire. "I had never fab'd a PCB before," says Johnson, "so I needed a lot of help to get this far!"

Johnson and Zaman are accepting pre-orders for the PrintNanny SDWire at $89 plus shipping and handling, with design files and source code published to GitHub under the permissive Apache 2.0 license for those who would like to make their own. Johnson is also planning to host an "ask the electrical engineer" Q&A on the Bitsy.ai website.