https://github.com/commaai/harness_tester_challenge

We designed a simple harness testing PCB and wrote some firmware for it. Can you figure out everything wrong with it?
https://github.com/commaai/harness_tester_challenge

Last synced: 8 months ago
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We designed a simple harness testing PCB and wrote some firmware for it. Can you figure out everything wrong with it?

• Host: GitHub
• URL: https://github.com/commaai/harness_tester_challenge
• Owner: commaai
• License: mit
• Created: 2024-05-23T15:35:15.000Z (about 2 years ago)
• Default Branch: master
• Last Pushed: 2025-05-25T16:17:34.000Z (about 1 year ago)
• Last Synced: 2025-05-25T17:26:41.515Z (about 1 year ago)
• Language: C++
• Homepage: https://comma.ai/leaderboard
• Size: 5.5 MB
• Stars: 39
• Watchers: 8
• Forks: 15
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          


Harness Tester Challenge



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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?

## The Harness Tester

We currently ship hundreds of [car-specific harnesses](https://www.comma.ai/shop/car-harness) to users every month, consisting of more than [40 different types](https://github.com/commaai/hardware/tree/master/harness/v3).

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

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

- Schematic ([PDF](./schematic.pdf) / [Web](https://kicanvas.org/?github=https%3A%2F%2Fgithub.com%2Fcommaai%2Fharness_tester_challenge%2Fblob%2Fmaster%2Fkicad_files%2Fhardware_challenge.kicad_sch))

- PCB layout ([Gerbers](./gerbers.zip) / [Web](https://kicanvas.org/?github=https%3A%2F%2Fgithub.com%2Fcommaai%2Fharness_tester_challenge%2Fblob%2Fmaster%2Fkicad_files%2Fhardware_challenge.kicad_pcb))

- Firmware ([Source](./firmware/))

The board is designed in [KiCad 8](https://www.kicad.org/), and the full project is available in an [exported archive](./kicad_project.zip).

There are a handful of intentional, show-stopping bugs hidden in each part. Find them, and [send](https://forms.gle/US88Hg7UR6bBuW3BA) them over to us for verification!

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

![PCB](./imgs/board.png)