We (mock) designed a simple harness testing PCB and wrote some firmware for it. Unfortunately, this board was designed and firmware was written on a Monday morning.

Can you figure out everything wrong with it?

We currently ship hundreds of car-specific harnesses to users every month, consisting of more than 40 different types.

As a simple wiring harness, we expect them to have a near-zero failure rate, so good testing is critical. This tester is designed to be capable of quickly verifying which pins are connected to which other pins.

A quick list of design goals is listed here:

• 12V DC input with transient and reverse polarity protection
• compatible with harnesses with up to 40 pins (through a pin header)
• start button and RGB LED are the user interface
• microSD card to store test results along with the current time (for statistical purposes)
• receive time by acquiring a GPS lock (ok, yes, this is just to make the board and firmware more interesting)

The challenge consists of 3 distinct parts, each riddled with more than a few bugs:

• Schematic (PDF / Web)
• PCB layout (Gerbers / Web)
• Firmware (Source)

The board is designed in KiCad 8, and the full project is available in an exported archive.

There are a handful of intentional, show-stopping bugs hidden in each part. Find them, and send them over to us for verification!

We're not looking for improvements or fixes; just submit a list of bugs.