at85c51snd3 ATMEL Corporation, at85c51snd3 Datasheet - Page 154

• Manufacturer Part Number: at85c51snd3
• Description: At85c51snd3 Single-chip Digital Audio Decoder - Encoder With Usb 2.0 Interface
• Manufacturer: ATMEL Corporation

Audio Codec
Audio Outputs
AT85C51SND3B1 &
AT85C51SND3B2
Anti-Pop Circuitry
Output Sources
Output Gain Control
154
AT85C51SND3B
The audio codec is controlled by four registers as detailed in Figure 74:
Figure 74. Audio Codec Block Diagram
The audio output system of AT85C51SND3B1 & AT85C51SND3B2 is based on a pair of
sigma-delta D/A converter used to convert the audio data with high linearity and high
S/N. It is enabled by setting the AOEN bit in ACCON (see Table 178).
Audio input system features are detailed in the following sections.
In order to avoid any noise when enabling the audio output system an anti-pop circuitry
has been implemented on the audio outputs (OUTR and OUTL). It consists in a dis-
charge circuit controlled by AODIS bit in ACAUX (see Table 179) and a preload circuit
controlled by AOPRE bit in ACAUX. Prior to enable the audio output system, user must
take care to discharge then charge the audio outputs.
The audio output source can come from either the audio processor or the stereo lines
Inputs sources. The selection of the source is done by setting or clearing the AOSSEL
bit in ACCON according to Table 156.
Table 156. Audio Codec Output Source Selection
Note:
Analog volume is controlled separately on both channel by setting the AORG4:0 bits in
ACORG for the right channel and the AOLG4:0 bits in ACOLG for the left channel.
Table 157 shows the gain value versus the programmed AORG or AOLG value.
MICBIAS
AOSSEL
1. Stereo or mono choice is done by the audio processor depending on the audio flow
OUTR
MICIN
OUTL
LINR
LINL
0
1
under decoding.
AODRV
ACCON.2
AORG4:0
ACORG.4:0
AOLG4:0
ACOLG.4:0
AMBEN
ACCON.5
Selection
Line Input (stereo)
Audio Processor (mono or stereo)
Generator
Σ
Bias
AOSSEL
ACCON.1
AMBVS
ACCON.6
1
0
1
0
AISSEL
ACCON.4
0
1
ACIPG.3
AILPG
AIPG2:0
ACIPG.2:0
(1)
A
A
A
AT85C51SND3B1&
AT85C51SND3B2 only
D
D
D
From Audio
Processor
To Audio
Processor
7632D–MP3–01/07