ADVANCE INFORMATION
VCT 38xxA
4. Audio Processing
4.1. Introduction
4.2. Input Select
The audio processing allows input selection and vol-
ume control for mono audio sources either from tuner
or from SCART input.
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.
4.3. Volume Control
AIN1
AIN2
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.
AOUT1
AIN3
−75 dB...−54 dB :
3 dB step size
−54 dB...+18 dB : 1.5 dB step size
AOUT2
Fig. 4–1: Audio processing
4.4. I2C-Bus Slave Interface
The input selection and analog volume is controlled via
the audio control register ACON. This I2C register is
activated by the chip address of the video back-end
processing (see Table 2–2 on page 32).
Table 4–1: Audio control register
2
I C Sub
address
Number
of bits
Mode
Function
Default Name
h’34
16
w
Audio Control
0 ACON
AVOL
bit [5:0]
volume control
000000
000001
...
mute
−75db
000111
001000
...
−57.0dB
−54.0dB
101011
101100
101101
...
−1.5dB
0.0dB
+1.5dB
110110
110111
111000
reserved
+15.0dB
+16.5dB
+18.0dB
bit [7:6]
bit [9:8]
audio input select 1
ASEL1
ASEL2
ALPM
00
01
10
11
mute
AIN1
AIN2
AIN3
bit [11:10] audio input select 2
00
01
10
11
mute
AIN1
AIN2
AIN3
bit[12]
low power mode
0
1
disable low power mode
enable low power mode
bit[15:13] reserved
Micronas
85
MICRONAS [ MICRONAS ]
