ADVANCE INFORMATION
VCT 38xxA
4. Audio Processing
4.1. Introduction
The audio processing allows input selection and vol-
ume control for mono audio sources either from tuner
or from SCART input.
4.2. Input Select
Both audio output channels can be switched to any of
the three audio input channels. Only the audio output
channel AOUT1 can be volume controlled.
AIN1
AIN2
AIN3
AOUT1
4.3. Volume Control
The analog volume control covers a range from
+18 dB and
−
75 dB. The lowest step is the mute posi-
tion. Step size is split into a 3-dB and a 1.5-dB range.
AOUT2
−
75 dB...
−
54 dB :
3 dB step size
−
54 dB...+18 dB : 1.5 dB step size
4.4. I
2
C-Bus Slave Interface
The input selection and analog volume is controlled via
the audio control register ACON. This I
2
C register is
activated by the chip address of the video back-end
processing (see Table 2–2 on page 32).
Fig. 4–1:
Audio processing
Table 4–1:
Audio control register
I
2
C Sub
address
Number
of bits
Mode
Function
Default
Name
h’34
16
w
Audio Control
bit [5:0]
volume control
000000
mute
000001
−
75db
...
−
57.0dB
000111
−
54.0dB
001000
...
101011
−
1.5dB
101100
0.0dB
101101
+1.5dB
...
110110
+15.0dB
110111
+16.5dB
111000
+18.0dB
bit [7:6]
reserved
bit [9:8]
audio input select 1
00
mute
01
AIN1
10
AIN2
11
AIN3
bit [11:10] audio input select 2
00
mute
01
AIN1
10
AIN2
11
AIN3
bit[12]
low power mode
0
disable low power mode
1
enable low power mode
bit[15:13] reserved
0 ACON
AVOL
ASEL1
ASEL2
ALPM
Micronas
85
MICRONAS [ MICRONAS ]
