FIR Filter Library
mikroPascal PRO for PIC32 includes a library for finite impulse response (FIR) filter. All routines work with fractional Q15 format.
A finite impulse response (FIR) filter is a type of a digital filter, whose impulse response (the filter's response to a delta function) is finite because it settles to zero in a finite number of sample intervals.
Library Routines
FIR_Radix
| Prototype |
function FIR_Radix(const ptrCoeffs : ^q15; FilterOrder : word; ptrInput : ^q15; InputLength : word; Index : word) : integer; |
|---|---|
| Description |
This function applies FIR filter to |
| Parameters |
|
| Returns |
Function returns value of the 
with : N - filter order
k - current index
|
| Requires |
Nothing. |
| Example |
// Filter setup:
// Filter kind: FIR
// Filter type: Lowpass filter
// Filter order: 3
// Filter window: Blackman
// Filter borders:
// Wpass:4000 Hz
program FIR;
var FILTER_ORDER : word;
inputSamples : array[3] of integer;
outputSamples : array[6] of integer;
i : word;
const COEFF_B : array[4] of integer = (0x0000, 0x1255, 0x1255, 0x0000);
procedure Init();
begin
inputSamples[0] := 0x4000;
inputSamples[1] := 0x2000;
inputSamples[2] := 0x1000;
BUFFFER_SIZE := 32;
FILTER_ORDER := 3;
end;
begin
Init();
for i:= 0 to 5 do
outputSamples[i] := FIR_Radix(@COEFF_B, FILTER_ORDER+1, @inputSamples, 3, i);
// outputSamples[0] = COEFF_B[0]*inputSamples[0];
// outputSamples[1] = COEFF_B[0]*inputSamples[1] + COEFF_B[1]*inputSamples[0];
// outputSamples[2] = COEFF_B[0]*inputSamples[2] + COEFF_B[1]*inputSamples[1] + COEFF_B[2]*inputSamples[0];
// .
// .
// .
end.
|
| Notes |
None. |
Copyright (c) 2002-2012 mikroElektronika. All rights reserved.
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