How to Create a Suzy Q Cable / SuzyQable

Introduction

A Suzy Q cable / SuzyQable is a cable used for Case Closed Debugging (CCD) on Chrome OS devices. This can be used to disable write-protection and firmware verification, allowing you to install an alternate operating system such as Linux on a Chromebook. Further information on this process can be found on the MrChromebox website.

Materials

  • USB-C breakout board
  • USB-A cable with 4 wires
  • 22k resistor
  • 56k resistor
  • Soldering iron and solder

Notes

The pinout of this breakout board is reversed as it labelled for the female version, so the D+ and D- pins are swapped. If you are using a different breakout board, make sure to check the pinout and adjust the wiring accordingly.

The Chromium documentation requires bridging the GND and VCC pins together, however the cable works fine without this, so you can just solder the wires to the appropriate pins on the breakout board without bridging them together. They also use a 45.3k resistor for the D- line, but a 56k resistor works.

Steps

  1. Solder the red wire (VCC) to the VCC pin on the USB-C breakout board.
  2. Solder the black wire (GND) to the GND pin on the USB-C breakout board.
  3. Solder the green wire (D+) to the A5 pin on the USB-C breakout board.
  4. Solder the white wire (D-) to the B5 pin on the USB-C breakout board.
  5. Solder the 22k resistor between the A8 and VCC pins on the USB-C breakout board.
  6. Solder the 56k resistor between the B8 and VCC pins on the USB-C breakout board.

Diagram

Breakout board diagram Breakout board diagram
Diagram of the breakout board with coloured positions of where the wires should be attached.

Finished Result

Breakout board photgraph (back-side)
The back of the breakout board of the Suzy Q cable, showing the soldering points and traces.

Breakout board photograph (front-side)
The front of the breakout board of the Suzy Q cable, showing the components and soldering points.

Sources

  1. Reddit - Making a ChromeOS Suzy Q Cable Tutorial
  2. Electronics Stack Exchange - DIY Chromebook Debug Cable (SuzyQable/Suzy-Q Cable)