Figure 45. Iir Filter Structure (Direct Form 1) - ST STM32G4 Series Reference Manual

RM0440
x[n]
Input:
•
X1 buffer contains the elements of vector X. It is a circular buffer of length N + 1+ d.
• X2 buffer contains the elements of coefficient vectors B and A concatenated
(b , b
0
Output:
•
Y buffer contains the output values, y
Parameters
•
The parameter P contains the length, N + 1, of the coefficient vector B in the range
[2:64].
•
The parameter Q contains the length, M, of the coefficient vector A in the range [1:63].
•
The parameter R contains the gain to be applied to the accumulator output. The value
output to the Y buffer is multiplied by 2

Figure 45. IIR filter structure (direct form 1)

b[0]
-1
Z
b[1]
x[n-1]
-1
Z
b[2]
x[n-2]
-1
Z
b[3]
x[n-3]
-1
Z
b[N]
x[n-N]
, b ..., b , a , a , ..., a
1 2 N 1 2
). It is a fixed buffer of length M+N+1.
M
. It is a circular buffer of length M + d.
n
R
, where R is in the range [0:7].
RM0440 Rev 1
Filter Math Accelerator (FMAC)
R
2
-1
Z
a[1]
y[n-1]
-1
Z
a[2]
y[n-2]
-1
Z
a[3]
y[n-3]
-1
Z
a[M]
y[n-M]
y[n]
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