Le58083
Data Sheet
COP 8. Write/Read B2 Filter Coefficients (B-IIR)
GCI Command
(96/97h)
R/W = 1: Read
R/W = 0: Write
D7
D6
D5
D4
1
D3
D2
1
D1
D0
Command
1
0
0
0
1
W/R
Coefficient Byte 1
Coefficient Byte 2
C411
C211
m411
m211
C311
C111
m311
m111
This function is described in Write/Read B1 Filter Coefficients on page 82.
Power Up and Hardware Reset (RST) Value = 0190h
(B11 = 0)
COP 9. Write/Read IIR Z Filter Coefficients
GCI Command
(9A/9B)
R/W = 0: Write
R/W = 1: Read
This command writes and reads only the IIR portion of the Z filter without affecting the FIR.
D7
D6
0
D5
D4
1
D3
D2
0
D1
D0
Command
1
0
1
1
R/W
I/O Data Byte 1
I/O Data Byte 2
I/O Data Byte 3
I/O Data Byte 4
I/O Data Byte 5
C45
C25
C26
C47
C27
m45
m25
m26
m47
m27
C35
C15
C16
C37
C17
m35
m15
m16
m37
m17
Cxy = 0 or 1 in the command above corresponds to Cxy = +1 or −1, respectively, in the equation below.
The Z-transform equation for the Z filter is defined as:
z5 • z6 • z7 • z–1
Hz(z) = z0 + z1 • z–1 + z2 • z–2 + z3 • z–3 + z4 • z–4 + ------------------------------------------
1 – z7 • z–1
Sample rate = 32 kHz
For i = 0–5 and 7
zi = C1i • 2–m1i{1 + C2i • 2–m2i[1 + C3i • 2–m3i(1 + C4i • 2–m4i)]}
z6 = C16 • 2–m16{1 + C26 • 2–m26
}
Power Up and Hardware Reset (RST) Values = 0190 0190 0190 0190 0190 0190 01 0190 (Hex)
(HZ(z) = 0)
See note under COP Command 2 on page 80.
Note:
Z6 is used for IIR filter scaling only. Its value is typically greater than zero but less than or equal to one. The input to the IIR filter section is first
increased by a gain of 1/Z6, improving dynamic range and avoiding truncation limitations through processing within this filter. The IIR filter output
is then multiplied by Z6 to normalize the overall gain. Z5 is the actual IIR filter gain value defined by the programmed coefficients, but it also
includes the initial 1/Z6 gain. The theoretical effective IIR gain, without the Z6 gain and normalization, is actually Z5/Z6.
85
Zarlink Semiconductor Inc.
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