From: eLinux.org

AVC-LAN

Contents

• 1 Introduction
• 2 Connections
• 3 Waveform
• 4 Protocol
• 5 Hardware
  • 5.1 Specific
  • 5.2 General Purpose
• 6 Hacks
• 7 Documentation Credit

Introduction

The AVC-LAN is part of the Body Electrical System Control and manages all audio and video related functions. The audio bus is described in Toyota's own words as follows:

AVC-LAN consist of audio visual systems such as the multi-display, navigation ECU, radio and
player, stereo component amplifier and gateway ECU. Gateway ECU has communication
circuit to correspond with different types of communication data. Different types of
communication data can be shared among communication parts after it goes through gateway
ECU (System Circuits: AVC-LAN Bus, “Prius Wiring Diagram” 80).

The system itself can be considered a subset of the IEBus Standard, which was delevoped by NEC electronics for automotive use. It is slightly faster than the BEAN Bus and has more data per command, but is still much slower than CAN Bus, since realtime speeds are not required.

Connections

Waveform

• Prep 7uS
• Sync 20uS
• Data 13uS

Protocol

This is an AVC-LAN message captured using a logic probe.

Hardware

Specific

• Renesas HA12240 Differential Transceiver
  • A2240 Package Marking
  • CA0008 Package Marking
  • CA0013 Package Marking
• NEC uPD6708 IEBus (Inter Equipment Bus) Protocol Controller
• NEC uPD72042 IEBus (Inter Equipment Bus) Protocol Controller

General Purpose

• LM239 comparator (can be used for receiver)
• PCA82C250 CAN Bus (can be used for driver)
• MCP2551 CAN Bus (can be used for driver)
• RS-485 Differential Transceiver ( can be used for both receiver and driver)
  • SN65HVD11 +3.3V
  • SN75HVD11 +5v

Hacks

• Marcin Slonicki's Toyota Corolla AVC-Lan MP3 player using:
  • ATmega8 is clocked at 14.7456 MHz with an external crystal
  • PCA82C250 CAN bus driver is used to drive the IEBus
  • LM239 comparator is required on top of the PCA82C250 to read from the IEBus
• Louis Frigon's Toyota Auxiliary Audio Input Enabler using:
  • ATmega8 is clocked at 8.00 MHz with the internal RC
  • ATmega8's internal analog comparator handles the receive side
  • ATmega8's two GPIOs as antagonist output pins perform the bus driver

Documentation Credit

• Jeremiah J. Flerchinger Whitepaper

Category:

• Networking