Datasheet

STA559BW Register description
Doc ID 18190 Rev 1 57/67
User-defined EQ
The STA559BW can be programmed for four EQ filters (biquads) per each of the two input
channels. The biquads use the following equation:
Y[n] = 2 * (b
0
/ 2) * X[n] + 2 * (b
1
/ 2) * X[n-1] + b
2
* X[n-2] - 2 * (a
1
/ 2) * Y[n-1] - a
2
* Y[n-2]
= b
0
* X[n] + b
1
* X[n-1] + b
2
* X[n-2] - a
1
* Y[n-1] - a
2
* Y[n-2]
where Y[n] represents the output and X[n] represents the input. Multipliers are 24-bit signed
fractional multipliers, with coefficient values in the range of 0x800000 (-1) to 0x7FFFFF
(0.9999998808).
40 0x28
Channel 1/2 - Biquad 5 or 8
for XO = 000
High-pass 2
nd
order filter
for XO ≠ 000
C12H0(b1/2) 0x000000
41 0x29 C12H1(b2) 0x000000
42 0x2A C12H2(a1/2) 0x000000
43 0x2B C12H3(a2) 0x000000
44 0x2C C12H4(b0/2) 0x400000
45 0x2D
Channel 3 - Biquad
for XO = 000
Low-pass 2
nd
order filter
for XO ≠ 000
C3H0(b1/2) 0x000000
46 0x2E C3H1(b2) 0x000000
47 0x2F C3H2(a1/2) 0x000000
48 0x30 C3H3(a2) 0x000000
49 0x31 C3H4(b0/2) 0x400000
50 0x32 Channel 1 - Prescale C1PreS 0x7FFFFF
51 0x33 Channel 2 - Prescale C2PreS 0x7FFFFF
52 0x34 Channel 1 - Postscale C1PstS 0x7FFFFF
53 0x35 Channel 2 - Postscale C2PstS 0x7FFFFF
54 0x36 Channel 3 - Postscale C3PstS 0x7FFFFF
55 0x37 TWARN/OC - Limit TWOCL 0x5A9DF7
56 0x38 Channel 1 - Mix 1 C1MX1 0x7FFFFF
57 0x39 Channel 1 - Mix 2 C1MX2 0x000000
58 0x3A Channel 2 - Mix 1 C2MX1 0x000000
59 0x3B Channel 2 - Mix 2 C2MX2 0x7FFFFF
60 0x3C Channel 3 - Mix 1 C3MX1 0x400000
61 0x3D Channel 3 - Mix 2 C3MX2 0x400000
62 0x3E Unused - -
63 0x3F Unused - -
Table 71. RAM block for biquads, mixing, scaling, bass management (continued)
Index
(Decimal)
Index (Hex) Description Coefficient Default