Hello!
In the demo Water_ground_lab, I have some question about an function. The function is follow code.
float filter_IIR_BiquadCascade(float DataIn, float *pFilterCoefs, float *pScaleVals, float *pDelay, uint16_t numStages)
{
float a1,a2;
float b0,b1,b2;
float y, input, output;
float scaleVal;
uint16_t indexStage;
uint16_t numCoefsStage;
uint16_t indexTemp;
numCoefsStage = 6;
input = DataIn;
for (indexStage = 0; indexStage < numStages; indexStage++)
{
indexTemp = numCoefsStage*indexStage;
b0 = pFilterCoefs[ indexTemp ];
b1 = pFilterCoefs[ indexTemp + 1];
b2 = pFilterCoefs[ indexTemp + 2];
a1 = pFilterCoefs[ indexTemp + 4];
a2 = pFilterCoefs[ indexTemp + 5];
scaleVal = pScaleVals[indexStage];
pDelay[indexTemp ] = scaleVal*input - a1*pDelay[indexTemp + 1] - a2*pDelay[indexTemp + 2];
y = b0*pDelay[indexTemp ] + b1*pDelay[indexTemp + 1] + b2*pDelay[indexTemp + 2];
pDelay[indexTemp + 2] = pDelay[indexTemp + 1];
pDelay[indexTemp + 1] = pDelay[indexTemp ];
input = y;
}
output = y;
return output;
}
In the main.c, the function is used in this line:
outputFilterPhase = filter_IIR_BiquadCascade(phaseUsedComputation, obj->pFilterCoefs, obj->pScaleVals, pDelay, IIR_FILTER_NUM_STAGES);
I cannot understand the this line. I want to know the function of
filter_IIR_BiquadCascade().
Can you help me?
