IIR Filter Library
mikroC PRO for dsPIC30/33 and PIC24 includes a library for Infinite Impulse Response (IIR) filter. All routines work with fractional Q15 format.
A infinite impulse response (IIR) filter is a type of a digital filter, whose impulse response (the filter's response to a delta function) is non-zero over an infinite length of time.
Library Routines
IIR_Radix
| Prototype |
unsigned IIR_Radix (const int BScale, const int AScale, const signed *ptrB, const signed *ptrA, unsigned FilterOrder, unsigned *ptrInput, unsigned InputLen, unsigned *ptrOutput, unsigned Index); // For dsPIC33EP family of MCUS :unsigned IIR_Radix (const int BScale, const int AScale, far const signed *ptrB, far const signed *ptrA, unsigned FilterOrder, far unsigned *ptrInput, unsigned InputLen, far unsigned *ptrOutput, unsigned Index); |
|---|---|
| Description |
This function applies IIR filter to |
| Parameters |
|
| Returns |
|
| Requires |
Nothing. |
| Example |
const unsigned int BUFFER_SIZE = 8;
const unsigned int FILTER_ORDER = 6;
const signed int COEFF_B[FILTER_ORDER+1] = {0x0548, 0x1FAE, 0x4F34, 0x699B, 0x4F34, 0x1FAE, 0x0548};
const signed int COEFF_A[FILTER_ORDER+1] = {0x4000, 0xB3FE, 0x5389, 0xD4D8, 0x10DD, 0xFCB0, 0x0052};
const unsigned int SCALE_B = 2;
const unsigned int SCALE_A = -1;
unsigned int inext; // Input buffer index
ydata unsigned int input[BUFFER_SIZE]; // Input buffer
ydata unsigned int output[BUFFER_SIZE]; // Output buffer
...
unsigned int CurrentValue;
CurrentValue = IIR_Radix(SCALE_B,
SCALE_A,
COEFF_B, // b coefficients of the filter
COEFF_A, // a coefficients of the filter
FILTER_ORDER+1, // Filter order + 1
input, // Input buffer
BUFFER_SIZE, // Input buffer length
output, // Input buffer
inext); // Current sample
|
| Notes |
Input and output samples must be in Y data space. |
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