STA321TR 查看數據表（PDF） - STMicroelectronics
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STA321TR Datasheet PDF : 157 Pages
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STA321
Digital processing stage
6.3.1
Presets
By default, each mixer output is connected to its corresponding input without any attenuation
and without any mixing with the other channels:
ch0_out = ch0_in, ch1_out = ch1_in, ch2_out = ch2_in, ch3_out = ch3_in.
6.4
6.4.1
Pre scaler
The pre scale block, which precedes the first biquad, could be used to attenuate the input
signal when the filters of the processing chain have a gain that could reach the clamping
value.
Each channel has a dedicated 24-bit signed multiplier in the range -1 (0x800000) to almost
+1 (0x7FFFFF).
Presets
By default, all pre-scale factors are set to 0x7FFFFF
6.5
Equalization, tone control and effects
Figure 18. EQ/tone block diagram
From
prescaler
Biquad
00
Biquad
07
Biquad
08
Biquad
09
Biquad
10
Reserved
Reserved
effects_en[0]
effects_en[1]
Reserved
RAM Reserved RAM Reserved RAM High RAM
pass
Deemph. RAM Reserved
RAM Treble RAM Bass
treb_sel
bass_sel
To
delay stage
Biquad
12
Biquad
11
Four channels of input data are fed to the EQ processing block which provides 13
user-programmable biquad filters per channel as shown in Figure 18 above.
A description of the biquad programming is given in Section 6.14 on page 44.
Some filter coefficients are pre-programmed and stored in the non-volatile memory in order
to supply particular EQ effects (see Figure 19 and Table 20 on page 38).
The selection of RAM, ROM bass/treble or ROM effects is made using registers
EFFS_EN_CHn on page 109 for the effects and BASS_SELn_R on page 111 and
TREB_SELn_R on page 113 for the bass/treble. Each biquad can be configured
independently.
Doc ID 15351 Rev 3
37/157
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