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

Typical Car Stereo Mount

• The standard car stereo size is referred to as single DIN. Most cars have single DIN stereo slots.
• Most car radios will slide directly into the single DIN slot without requiring an additional adapter kit.
• The second most common car stereo slot size is the DOUBLE DIN stereo opening. DOUBLE DIN slots are twice as tall as the standard single DIN slots, but they have the same width as single DIN stereos.
• Single DIN slot is:
  • 180mm (7-1/8”) width
  • 50mm (2-1/8”) height
• Double DIN slot is:
  • 180 x 100.3 mm
• ISO 7736 is a standard size for dashboard mounted head units, for car audio.
  • It was originally established by the German national organization for standardization, the Deutsches Institut für Normung, as DIN 75490, and is therefore commonly referred to as the DIN size.
  • It was adopted by the International Organization for Standardization in 1984.

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...