RM0440 Rev 4 495/2126
RM0440 Filter math accelerator (FMAC)
513
y
n
= B.X
n
, where X
n
= [x
n-N
,...,x
n
] is composed of the N+1 elements of X at indexes n - N to
n.
This function corresponds to a finite impulse response (FIR) filter, where vector B
contains
the filter coefficients and vector X
the sampled data.
The structure of the filter (direct form) is shown in Figure 47.
Figure 47. FIR filter structure
Note that the cross correlation vector can be calculated by reversing the order of the
coefficient vector B
.
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 vector B
. It is a fixed buffer of length N + 1.
Output:
• Y buffer contains the output values, y
n
. It is a circular buffer of length d.
Z
-1
x[n]
b[1]
x[n-1]
b[2]
Z
-1
b[3]
x[n-2]
y[n]
Z
-1
b[0]
b[N]
Z
-1
x[n-3]
x[n-N]
2
R
MSv47126V1
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