at85c51snd3b ATMEL Corporation, at85c51snd3b Datasheet - Page 152

• Manufacturer Part Number: at85c51snd3b
• Description: Single-chip Digital Audio Decoder - Encoder With Usb 2.0 Interface
• Manufacturer: ATMEL Corporation

Digital Volume Control
Equalizer Volume Control
Bass Boost Effect
Virtual surround Effect
Equalizer Bar-Graph
152
AT85C51SND3B
The digital volume is controlled separately on right and left channel by setting the
DVR4:0 and DVL4:0 bits respectively in APRDVOL and APLDVOL according to
Table 154.
Table 154. Digital Volume Control Gain
Note:
A 3-band equalizer control is provided for tone adjustment or predefined tone shapes
like classic, jazz, rock…
The equalizer gain is controlled in each band by programing DVB4:0 in APBDVOL for
the bass band, DVM4:0 in APMDVOL for the medium band and DVT4:0 in APTDVOL
for the treble band according to Table 154. Cut frequencies are defined in Table 155.
In order to optimize the power consumption, the 3-band equalizer can be disabled by
setting EQUDIS in AUCON. In this case the band gain control is saved but no filtering is
applied.
Table 155. Equalizer Band Frequency
A bass boost effect can be established by setting BBOOST bit in AUCON. It consists in
a gain increase of +6 dB in the frequency range under 200 Hz.
A virtual surround effect can be established by setting VSURND bit in AUCON. It con-
sists in applying a spatial effect to sound on both right and left channels.
An 8-band bar-graph equalizer allows dynamic audio volume report inside 8 frequency
bands. To read the level of each band, first select the band by setting the EQBS2:0 bits
in APEBS from 000b (lowest frequency band) to 111b (highest frequency band) then get
the 5-bit band level by reading EQLEV4:0 bits in APELEV.
DVx4:0
00000
00001
00010
00100
00101
01000
01001
01010
00011
00110
00111
1. When DVR4:0 and DVL4:0 are set to mute, audio processor is still sending data to
Medium
Treble
Band
Bass
the audio codec or the audio interface with data set to the corresponding 0 value.
Gain Value
+6 dB
+4 dB
+2 dB
+0 dB
-2 dB
-4 dB
-6 dB
-8 dB
-10 dB
-12 dB
-14 dB
Frequencies
F < 750 Hz
750 Hz < F < 3300 Hz
F > 3300 Hz
DVx4:0
01011
01100
01101
10000
10001
10010
10011
10100
10101
01110
01111
Gain Value
-16dB
-18 dB
-20 dB
-22 dB
-24 dB
-26 dB
-28 dB
-30 dB
-32 dB
-34 dB
-36 dB
DVx4:0
10110
11000
11001
11010
10111
11011
11100
11101
11110
11111
Gain Value
-38 dB
-40 dB
-42 dB
-44 dB
-46 dB
-48 dB
-50 dB
-52 dB
-54 dB
Mute
7632C–MP3–11/06
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