I work in Code Composer Studio Version: 6.0.1.00040 with the card LCDK C6748, but I think this is a more general question, relating to CCS generally. I'm trying to implement LMS for cancelling acoustic echoes, this is the skeleton of my .c file:
void waitForInterrupt() < while (flag==0) <>flag=0; // reach this line only when flag == 1 > interrupt void interrupt4(void) < // Inputs inputRight_micSignal = (float)input_right_sample(); // Outputs outputLeft_referenceSignal= whiteNoiseSample; codec_data.channel[RIGHT]= (uint16_t)outputRight_cleanedSound; codec_data.channel[LEFT]= (uint16_t)outputLeft_referenceSignal; output_sample(codec_data.uint); flag = 1; >void main() < // variables decelerations int i; float filter_output; // initialising filter coefficients for (i=0 ; i// initialising the interrupt routine L138_initialise_intr(FS_8000_HZ,ADC_GAIN_0DB,DAC_ATTEN_0DB,LCDK_MIC_INPUT); while(1) // adaptive filtering routine < waitForInterrupt(); whiteNoiseSample = getPrnFiltered(); for (i = ADAPTIVE_FILT_SIZE-1; i >0; i--) // update delay line - TDL:merge later with w loop (still make sure no magic NaN's appear) < x[i] = x[i-1]; >x[0] = outputLeft_referenceSignal; // input to adaptive filter filter_output = 0; //reseting filter output // compute adaptive filter output for (i = 0; i < ADAPTIVE_FILT_SIZE; i++) filter_output += (w[i]*x[i]); outputRight_cleanedSound = inputRight_micSignal - filter_output; // compute error for (i = ADAPTIVE_FILT_SIZE-1; i >= 0; i--) // update weights and delay line < w[i] = w[i] + beta*outputRight_cleanedSound*x[i]; // w[i]+=beta*"error"*"reference" >from some reason when I put the arrays x[] and w[] in the "watch table" and I suspend the running of the program (in order to examine w[] coefficients after awhile, I see that it is full of NaN's - while x[] contains "regular" values. when I put breakpoint inside the line where w[] is calculated:
w[i] = w[i] + beta*outputRight_cleanedSound*x[i]; // w[i]+=beta*"error"*"reference"
I see the flow goes there. What could be the reason for the NaN's? Is there a way to watch w[] in the "wach table"?