Mercedes-Benz ML320. Manual — part 241

RADIO AND NAVIGATION MODULE, DESIGN - GF82.61-P-4109-03GI

The following is integrated into the radio and navigation module (A2/56) (maximum scope):

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Graphic compatible 5" LCD color display

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Navigation processor with GPS receiver and gyrosensor

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Single CD drive for playing audio CD's (option)

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Navigation CD drive for loading navigation data or for playing audio CD's (optional)

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Telephone unit (optional)

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Radio tuner

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Audio amplifier

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CC player

The radio and navigation module (A2/56) has the following digital interfaces:

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Digital data bus (D2B)

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K-cable (diagnosis interface)

Fig. 58: Identifying Radio And Navigation Module (A2/56) Design

RADIO AND NAVIGATION MODULE, FUNCTION - GF82.61-P-4109-04A

Models 163, 168, 170, 208, 209, 210 with code 353

Processing key signals

The controls on the radio (A2) are read in via I/O ports of the microcontroller and made available to the central
computer. Depending on the system function the button operations are processed further in the central computer
or conveyed via the Digital Data Bus (D2B) or interior CAN (CAN B) in the form of a data telegram to the
system components involved (e.g. CD changer).

Display

2001 Mercedes-Benz ML320

1998-2005 ACCESSORIES & BODY, CAB Electrical System - Body - 163 Chassis

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The display of the radios (A2) has 197 x 32 pixels. Texts are displayed in 3 lines.

After particular functions are called (e.g. navigation), the bottom line shows a variable inscription for the row of
buttons underneath (multifunction buttons). As a result the system can be operated very conveniently with a few
buttons, as the function which is activated when the button is operated, is shown in plain text (e.g. LANG,
ITEM, DYN, CLOCK etc.).

Audio signal output

The audio signals of the various sources (CD, voice output for navigation etc.) are processed by the radio (A2)
and amplified before output by the vehicle speakers.

On models 168, 170, 208 and 210 with the sound system (code 810) the audio signals are finally amplified

by the amplifier for the sound system (N40/3). For this, the audio source data (low-frequency signals) are
transmitted to the amplifier for the sound system (N40/3) via separate lines.

On models 163 and 209 the final amplification of the audio signal is performed by the sound amplifier

(A2/13). All the data are transmitted via the D2B.

Audio mute

An incoming phone call activates the audio mute function (a separate signal input exists on the radio (A2) for
this). When the audio mute function is activated, the current audio source (e.g. radio) is muted automatically.

Navigation processor, GPS control module and gyrosensor

The navigation processor is the central component of the navigation system.

It is integrated into the radio (A2) and from the incoming signals continuously calculates the location and once
the destination is entered calculates the route for navigation. The GPS receiver is integrated into the navigation
processor. It evaluates the satellite signals and calculates from them the vehicle position in degrees longitude
and latitude. Various GPS antennae are used to receive these signals depending on the vehicle model:

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Model 163: telephone and GPS roof antenna (A2/49)

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Models 168, 208.3, 210: GPS antenna (A2/49a2)

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Models 170, 208.4: GPS rear antenna (A2/23a2)

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Model 209: GPS antenna (A2/23)

Reception from at least 3 satellites is necessary for exact GPS position calculation. A free view of the sky is

required for this purpose.

The integrated gyrosensor continuously senses every change in direction of the vehicle. Evaluation of this data
is accomplished by the navigation processor.

Calibration of the gyrosensor is not required.

2001 Mercedes-Benz ML320

1998-2005 ACCESSORIES & BODY, CAB Electrical System - Body - 163 Chassis

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DVD drive and DVD

The DVD drive of the radio (A2) reads data from the navigation DVD inserted and makes this available to the
navigation processor via the data bus inside the device.

Audio CDs can also be played.

The following are located on the navigation DVD:

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Program data for the navigation computer

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Voice segments for voice output

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Map data.

A distinction is made between digitized and non-digitized areas within the DVD map area:

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Villages, towns, roads, intersections and their attributes (e.g. one-way streets, no turns etc.) are recorded
in the digitized map area.

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Included in the non-digitized areas are, for example company/private grounds, farms, small housing
estates, tracks across fields and areas between villages.

No data is available here.

Diagnosis interface (K-line) and fault management of D2B-components

During operation, the system stores all occurring faults in the nonvolatile memory. It is not possible to output
the fault via the display of the radio (A2).

The radio's (A2) fault management also includes the D2B-components connected. For this purpose, each D2B
component has its own DTC memory. The faults are transmitted from the corresponding components via the
D2B to the radio (A2) and can then be read out via the diagnosis interface

RADIO AND NAVIGATION MODULE, FUNCTION - GF82.61-P-4109-04GI

Processing button actuations

The control buttons and switches on the function keypad on the radio and navigation module (A2/56) are read
in via the I/O ports of the microcontroller and transferred to the central processor. Depending on the system
function the button actuations are processed in the central processor or relayed to the other system components
via the digital data bus ( D2B ) in form of a data telegram.

Graphic preparation and image output

The graphics subsystem handles the preparation and output of the operating displays. The operating displays are
output internally to the display by the graphic subsystem via the RGB output ( R =red, G =green, B =blue).

The RGB signal contains information and amplitudes of the three basic colors R ed, G reen and B lue as well

2001 Mercedes-Benz ML320

1998-2005 ACCESSORIES & BODY, CAB Electrical System - Body - 163 Chassis

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as a synchronization signal. The electronic control in the display unit evaluates the RGB signal and actuates the
individual pixels line by line according to color and intensity.

A horizontal synchronization pulse is output at the end of each line. The electronic circuitry of the display unit
then starts the next line. After reaching the last line on the display, a vertical synchronization pulse is output and
the electronic circuitry starts again with the first line.

Audio signal output

The audio signals from the various sources (CD, voice output for route guidance, ...) are processed by the radio
and navigation module (A2/ 56) and amplified before output over the vehicle loudspeakers . On vehicles
with sound system (code 810) final amplification of the audio signals is accomplished by the sound amplifier
(A2/13) . For this purpose audio source data is transmitted to the sound amplifier (A2/13) via the digital data
bus ( D2B ).

Diagnosis interface (K bus) and D2B component error management

During the radio and navigation module (A2/56) mode the system stores all errors which occur in the non-
volatile memory. These errors can then be read out on the diagnostic interface (K bus) with Star diagnosis .
Output of the errors on the display unit is not possible.

Error management also includes components connected to the digital data bus ( D2B ).

Each D2B component has its own DTC memory . The errors are transmitted to the radio and navigation
module (A2/56) via the digital data bus (D2B) on request by STAR diagnosis and can then be read out with the
diagnostic interface.

Navigation processor and GPS control module

The navigation processor is the central component of the radio and navigation module (A2/56) . It is
integrated into the radio and navigation module (A2/56) and calculates the location and vehicle route from the
incoming signals after entering the route.

The GPS control module is a part of the navigation processor. It evaluates the satellite signals distributed by
the CTEL/GPS roof antenna (A2/49) and the CTEL and GPS antenna splitter (A2/57) and calculates with
this information the vehicle position.

CD-ROM and CD drive

With the aid of the navigation CD drive it is possible to read data from the special navigation CD or play
audio CD's or play .

The following is stored on the navigation CD-ROM :

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Program data for execution in navigation processor

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Voice data for voice output

2001 Mercedes-Benz ML320

1998-2005 ACCESSORIES & BODY, CAB Electrical System - Body - 163 Chassis

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