
48
Am79Q02/021/031 Data Sheet
35, 36. Write/Read Z Filter Coefficients (FIR and IIR)
MPI Command
(84/85h)
R/W = 0: Write
R/W = 1: Read
This command writes and reads both the FIR and IIR filter sections simultaneously.
The Z-transform equation for the Z filter is defined as:
Sample rate = 32 kHz
For i = 0 to 5 and 7
Power Up and Hardware Reset (RST) Values = 0190 0190 0190 0190 0190 0190 01 0190 (Hex)
(Hz(z) = 0)
See note under Commands 31 and 32.
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.
D7
D6
D5
D4
D3
D2
D1
D0
Command
1
0
1
0
R/W
I/O Data Byte 1
C40
m40
C30
m30
I/O Data Byte 2
C20
m20
C10
m10
I/O Data Byte 3
C41
m41
C31
m31
I/O Data Byte 4
C21
m21
C11
m11
I/O Data Byte 5
C42
m42
C32
m32
I/O Data Byte 6
C22
m22
C12
m12
I/O Data Byte 7
C43
m43
C33
m33
I/O Data Byte 8
C23
m23
C13
m13
I/O Data Byte 9
C44
m44
C34
m34
I/O Data Byte 10
C24
m24
C14
m14
I/O Data Byte 11
C45
m45
C35
m35
I/O Data Byte 12
C25
m25
C15
m15
I/O Data Byte 13
C26
m26
C16
m16
I/O Data Byte 14
C47
m47
C37
m37
I/O Data Byte 15
C27
m27
C17
m17
H
z z
() z
0
z
1
z
1
–
z
2
z
2
–
z
3
z
3
–
z
4
z
4
–
z
5
z
6
z
7
z
1
–
1z
7
z
1
–
---------------------------------------
+
++
=
z
i
C1i
2
m1i
–
1C2i
2
m2i
–
1C3i
2
m3i
–
1C4i
2
m4i
–
+
()
+
[]
+
{}
=
z
6
C16
2
m16
–
1C26
2
m26
–
+
{}
=