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Circuit Descriptions and List of Abbreviations

Figure 9-4 Audio Path

The processing part consists mainly of the following
components:
•

MSP3415G: a DSP sound processor from Micronas. This
component is able to do all kinds of digital signal
processing like volume, bass/treble, UltraBass and
balance. It has analogue inputs and outputs, as well as an
I

S in/output used for digital audio delay.

•

RAM with its logic to be able to store the I

S information for

audio delay.

•

Anti-plop/ mute circuit: which is necessary to prevent
disturbances on the audio lines during start-up or
switching.

•

TEA6422: a matrix switch of ST. This component is able to
switch six inputs to three different outputs (only used in the
Enhanced version).

MSP3415G

Ultra Bass
Because of the closed box implementation in FM242, a
common DBE solution will not give an optimal bass
performance. A closed box needs a substantial boost over a
wide frequency range, while DBE operates in a limited
frequency region.
Adaptive Ultra Bass 2 (UB2) is a suitable alternative. This
feature is based on the psycho-acoustic effect of the missing
fundamental, and gives the impression of a deep bass while
the loudspeakers do not reproduce these low frequencies. This
feature is implemented in the MSP3415G.

Audio delay
To compensate for 'lip sync error' (the difference in time
between the aural and visual perceptions), two different audio
delays are selectable via the customer's menu (one for the
Receiver box and one for the Monitor).

This is done at the audio processor IC7812 via an I

S bus and

an additional delay circuit (IC7880 - 7882).
One can select delays of 24 ms (I2S_DATA_IN1) and 40 ms
(I2S_DATA_IN2), or no delay.
In case of a delay, the AUDIO_L/R_IN is re-routed as
I2S_DATA_OUT to the audio delay circuit and, depending on
the selected delay, returned as I2S_DATA_IN1 or
I2S_DATA_IN2, resulting in AUDIO_L/R_OUT.

Anti-plop/Mute
In several cases, it is necessary to mute the sound output. This
muting is handled by the MSP sound processor, or by the
Receiver box in case of TV-mode.
•

In Monitor mode:
–

During switch 'on/off' of the monitor.

–

During source change.

–

During video or sync loss, or

–

By a user action (A/V-mute or mute).

•

In TV mode:
–

During switch 'on/off' of the Monitor/Receiver box.

–

During source change in the Receiver box.

–

During video or sync loss, or

–

By a user action (mute).

9.4.4

Control (Diagrams SC7, 8 and 9)

Introduction
As a main controller, better known as OTC (On screen display,
Teletext and Control). It is a 8051 (XA) based controller from
Philips Semiconductors, the SAA5801H.
Although the OTC is the main controller, it acts as a 'slave'
when communicating with the PixelWorks IC via the I

C-bus 2.

When the monitor is connected to an F21R Receiver box, the
UART commands from the Receiver box will control the
monitor.

CL 26532038_012.eps

280302

VGA1

Audio-VGA-in

7798
(Enhanced only)

PRE-out1 (L)

PRE-out2 (R)

In 4

I2S

7812