Vehicle Head Unit

The goal of this project is to eventually create a vehicle media receiver / head unit that can replace a traditional stereo unit. It starts with a simplified proof-of-concept and is designed to build on previous work with each new iteration.

Research

Typical Car Stereo Wiring

General Information

• Cars are generally standardized with an electrical system voltage that will be in the range of 12 to 14 V DC depending on the whether or not the engine is running.
• Current wise, the stereo probably had its own fuse and you can find the value of the fuse either in the owner's manual or by looking at the fuse itself.
  • It's likely 5-15 Amps.
• Connectors for car audio are defined in ISO 10487.

Stereo Wiring Harness

Information comes from the12volt.com. Wikipedia also has a great page with information.

• Memory / Constant 12V(+)
  • Yellow
  • Turning the car's ignition on and off as well as turning the headlights on and off should not change the voltage on this wire.
• Switch / Accessory
  • Red
  • Only provides 12V when the car's ignition is set the On or Accessory mode.
• Ground
  • Black

Phase 1 - Proof of Concept

This is (almost) the simplest possible replacement for a head unit. It's basically a stereo delete with a few extra features.

Features

• Indicator LEDs
  • Battery Present
  • Power On
• A USB charging port

Requirements

• Connection to three wires
  • Constant +12V (Yellow)
  • On/Acc (Red)
  • Ground (Black)
• A voltage converter
• LEDs and other components
• Faceplate, case, mounting...