Le58083
Data Sheet
84/85h Write/Read Z Filter Coefficients (FIR and IIR)
MPI Command
R/W = 0: Write
R/W = 1: Read
This command writes and reads both the FIR and IIR filter sections simultaneously.
D7
D6
0
D5
D4
0
D3
D2
1
D1
D0
R/W
Command
1
0
0
0
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
I/O Data Byte 6
I/O Data Byte 7
I/O Data Byte 8
I/O Data Byte 9
I/O Data Byte 10
I/O Data Byte 11
I/O Data Byte 12
I/O Data Byte 13
I/O Data Byte 14
I/O Data Byte 15
C40
C20
C41
C21
C42
C22
C43
C23
C44
C24
C45
C25
C26
C47
C27
m40
m20
m41
m21
m42
m22
m43
m23
m44
m24
m45
m25
m26
m47
m27
C30
C10
C31
C11
C32
C12
C33
C13
C34
C14
C35
C15
C16
C37
C17
m30
m10
m31
m11
m32
m12
m33
m13
m34
m14
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 to 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 Command 80/81h on page 54.
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 in-
cludes the initial 1/Z6 gain. The theoretical effective IIR gain, without the Z6 gain and normalization, is actually Z5/Z6.
55
Zarlink Semiconductor Inc.
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