STA32813TR View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
STA32813TR Datasheet PDF : 57 Pages
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STA328
User programmable processing
7.5
Calculating 24-bit signed fractional numbers from a dB value
The pre-scale, mixing, and post-scale functions of the STA328 use 24-bit signed fractional
multipliers to attenuate signals. These attenuations can also invert the phase and therefore
range in value from -1 to +1. It is possible to calculate the coefficient to utilize for a given
negative dB value (attenuation) via the equations below.
" Non-inverting phase numbers 0 to +1:
" Coefficient = round(8388607 * 10(dB / 20))
" Inverting phase numbers 0 to -1:
" Coefficient = 16777216 - round(8388607 * 10(dB / 20))
As can be seen by the preceding equations, the value for positive phase 0 dB is 0x7FFFFF
and the value for negative phase 0 dB is 0x800000.
7.6
7.6.1
7.6.2
7.6.3
7.6.4
7.6.5
User defined coefficient RAM
Coefficient address register 1 (addr 0x16)
D7
CFA7
0
D6
CFA6
0
D5
CFA5
0
D4
CFA4
0
D3
CFA3
0
D2
CFA2
0
D1
CFA1
0
Coefficient b1data register bits 23:16 (addr 0x17)
D7
C1B23
0
D6
C1B22
0
D5
C1B21
0
D4
C1B20
0
D3
C1B19
0
D2
C1B18
0
Coefficient b1data register bits 15:8 (addr 0x18)
D1
C1B17
0
D7
C1B15
0
D6
C1B14
0
D5
C1B13
0
D4
C1B12
0
D3
C1B11
0
D2
C1B10
0
D1
C1B9
0
Coefficient b1data register bits 7:0 (addr 0x19)
D7
C1B7
0
D6
C1B6
0
D5
C1B5
0
D4
C1B4
0
D3
C1B3
0
D2
C1B2
0
D1
C1B1
0
Coefficient b2 data register bits 23:16 (addr 0x1A)
D7
C2B23
0
D6
C2B22
0
D5
C2B21
0
D4
C2B20
0
D3
C2B19
0
D2
C2B18
0
D1
C2B17
0
D0
CFA0
0
D0
C1B16
0
D0
C1B8
0
D0
C1B0
0
D0
C2B16
0
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