BMW E65 User Manual download pdf (Page 36)

E65 Bus Systems

Optical Bus

The MOST bus is a plastic optical waveguide. The MOST bus is coded in green in the E65.

The light wavelength is 650 nm (red light). The MOST bus requires the following converter

components:

• Optical transmitter

• Optical receiver

Each control unit of the MOST framework contains a transmitter and a receiver. The trans-

mitter and receiver have been developed by BMW. The low closed circuit (rest) current

properties of the transmitter and receiver enable optical wake-up by the MOST bus.

Optical Transmitter

A driver is fitted in the transmitter. The

driver energizes an LED (light-emitting

diode).

The LED transmits light signals on the

MOST bus (650 nm light, i.e. red, visi-

ble light). The repeat frequency is 44.1

KHz.

The sensing frequency on a CD player and for audio is 44.1 MHz; this means than no addi-

tional buffer is required, yet another reason why this bus system is so efficient for multi-

media.

Optical Receiver

The receiver receives the data from the

MOST bus. The receiver consists of:

• An LED

• A pre-amplifier

• A wake-up circuit

• An interface that converts the optical signal into an electrical signal

The receiver contains a diode that converts the optical signal into an electrical signal. This

signal is amplified and further processed at the MOST network interface.

Transmitter

Light

LED

Driver

Receiver

Light

LED

Pre-

Amp.

Wake

-up

KT-9389

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BMW E65 User Manual Page 36