RE_SWC - A volume knob kit for your car

Features:

• Simple, plug-and-play solution. Mount the volume knob to a panel in the car, solder two wires into your stereo's steering wheel control input and you are good to go
• Compatible with many headunit brands and types
  • Generic Resistive (resistance learning supported by headunits)
  • JVC ¹
  • Kenwood ²
  • Alpine
  • Pioneer & Sony
  • USB HID (single cable control for any android based units)
• USB C powered. Most headunits have female USB connectors for you to plug this into and power up
• MCU: WCH CH32X035 programnmed with the Arduino Framework
• Interrupt-driven firmware results in a smooth, user-freindly experience
• Firmware via USB upload - easy updates if required
• Fully open source hardware and firmware. This includes all design files, BOM, firmware, etc

¹ JVC forces incremental volume control above certain values on select models. I am yet to find a way to bypass this.

² Kenwood forces incremental volume control above certain values on select models. I have found a way to bypass this and have implemented it by default in the firmware. This may or may not work for your unit and your miles may vary.

Functions

INPUT	GENERIC RESISTIVE	JVC	KENWOOD	ALPINE	Pioneer & Sony
Volume Knob CW	Any	Volume +	Volume +	Volume +	Volume +
Volume Knob CCW	Any	Volume -	Volume -	Volume -	Volume -
Button Short Press	Any	Mute	Mute	Mute	Mute
Button Long Press	Any	Next Track	Next Track	Next Track	Next Track
Button Double Press	Enter Learning Mode	Previous Track	Previous Track	Previous Track	Previous Track

User Guide

The User Guide can be found in the Docs subfolder of this repository

Firmware

The FW for this project is also completely open source and hosted here on GitHub

Why did I make this?

• No kits like this exist: a plug-and-play solution to add a volume knob back into your car. Mount the volume knob to a panel in the car, solder two wires and you are good to go

My headunit does not have a USB socket to power this??

No worries, purchase an automotive 12V to USB adapter and plug this into it.

• Note: The 12V rail in cars is harsh. Do not cheap out on this component

FCC Compliance Statement

This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions:

1. This device may not cause harmful interference, and
2. this device must accept any interference received, including interference that may cause undesired operation.

Please note, if you manufacture this yourself, FCC compliance is not valid. Pounamu Electronics is the sole manufacturer listed on the FCC SDoC.

RESWC Impact Map

RESWC Impact Map

3D Printed Housings - Design Files

You can find all design and production files for all housings (controller and encoder PCB) in this repo or head to thingiverse and download: Thingiverse - RE_SWC Housings

Volume Knob Dimensions

Controller Housing Dimensions

Board Bringup and O'Scope Captures

3V3 Regulator

Encoder CW, CCW Rotation and Button Press

SPI Bus (Mode 0)

Apline SWC Output