Digital Volume Control
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
DVx4:0
00000
00001
00010
00011
00100
00101
00110
00111
01000
01001
01010
Gain Value
+6 dB
+4 dB
+2 dB
+0 dB
-2 dB
DVx4:0
01011
01100
01101
01110
01111
10000
10001
10010
10011
10100
10101
Gain Value
-16dB
DVx4:0
10110
10111
11000
11001
11010
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(1)
-18 dB
-20 dB
-22 dB
-24 dB
-26 dB
-28 dB
-30 dB
-32 dB
-34 dB
-36 dB
-4 dB
-6 dB
-8 dB
-10 dB
-12 dB
-14 dB
Note:
1. When DVR4:0 and DVL4:0 are set to mute, audio processor is still sending data to
the audio codec or the audio interface with data set to the corresponding 0 value.
Equalizer Volume Control
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
Band
Bass
Frequencies
F < 750 Hz
Medium
Treble
750 Hz < F < 3300 Hz
F > 3300 Hz
Bass Boost Effect
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.
Virtual surround Effect
Equalizer Bar-Graph
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.
152
AT85C51SND3Bx
7632A–MP3–03/06
ATMEL [ ATMEL ]
