Contents

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