Datasheet
Register description STA559BW
56/67 Doc ID 18190 Rev 1
Writing a set of coefficients to RAM
1. Write 6-bits of starting address to I
2
C register 0x16.
2. Write top 8-bits of coefficient b1 in I
2
C address 0x17.
3. Write middle 8-bits of coefficient b1 in I
2
C address 0x18.
4. Write bottom 8-bits of coefficient b1 in I
2
C address 0x19.
5. Write top 8-bits of coefficient b2 in I
2
C address 0x1A.
6. Write middle 8-bits of coefficient b2 in I
2
C address 0x1B.
7. Write bottom 8-bits of coefficient b2 in I
2
C address 0x1C.
8. Write top 8-bits of coefficient a1 in I
2
C address 0x1D.
9. Write middle 8-bits of coefficient a1 in I
2
C address 0x1E.
10. Write bottom 8-bits of coefficient a1 in I
2
C address 0x1F.
11. Write top 8-bits of coefficient a2 in I
2
C address 0x20.
12. Write middle 8-bits of coefficient a2 in I
2
C address 0x21.
13. Write bottom 8-bits of coefficient a2 in I
2
C address 0x22.
14. Write top 8-bits of coefficient b0 in I
2
C address 0x23.
15. Write middle 8-bits of coefficient b0 in I
2
C address 0x24.
16. Write bottom 8-bits of coefficient b0 in I
2
C address 0x25.
17. Write 1 to WA bit in I
2
C address 0x26.
The mechanism for writing a set of coefficients to RAM provides a method of updating the
five coefficients corresponding to a given biquad (filter) simultaneously to avoid possible
unpleasant acoustic side-effects. When using this technique, the 6-bit address specifies the
address of the biquad b1 coefficient (for example, 0, 5, 10, 20, 35 decimal), and the
STA559BW generates the RAM addresses as offsets from this base value to write the
complete set of coefficient data.
Table 71. RAM block for biquads, mixing, scaling, bass management
Index
(Decimal)
Index (Hex) Description Coefficient Default
0 0x00
Channel 1 - Biquad 1
C1H10(b1/2) 0x000000
1 0x01 C1H11(b2) 0x000000
2 0x02 C1H12(a1/2) 0x000000
3 0x03 C1H13(a2) 0x000000
4 0x04 C1H14(b0/2) 0x400000
5 0x05 Channel 1 - Biquad 2 C1H20 0x000000
…… … … …
19 0x13 Channel 1 - Biquad 4 C1H44 0x400000
20 0x14
Channel 2 - Biquad 1
C2H10 0x000000
21 0x15 C2H11 0x000000
…… … … …
39 0x27 Channel 2 - Biquad 4 C2H44 0x400000