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Changes added for the DISCO-L476VG
algorithm/algorithm.cpp
- Committer:
- MaximGordon
- Date:
- 2016-04-20
- Revision:
- 1:e88f22c6c1b0
- Parent:
- 0:346a7fa07998
- Child:
- 2:560e76e77544
File content as of revision 1:e88f22c6c1b0:
/** \file algorithm.cpp ****************************************************** * * Project: MAXREFDES117# * Filename: algorithm.cpp * Description: This module calculates the heart rate/SpO2 level * * Revision History: *\n 1-18-2016 Rev 01.00 SK Initial release. *\n * * -------------------------------------------------------------------- * * This code follows the following naming conventions: * *\n char ch_pmod_value *\n char (array) s_pmod_s_string[16] *\n float f_pmod_value *\n int32_t n_pmod_value *\n int32_t (array) an_pmod_value[16] *\n int16_t w_pmod_value *\n int16_t (array) aw_pmod_value[16] *\n uint16_t uw_pmod_value *\n uint16_t (array) auw_pmod_value[16] *\n uint8_t uch_pmod_value *\n uint8_t (array) auch_pmod_buffer[16] *\n uint32_t un_pmod_value *\n int32_t * pn_pmod_value * * ------------------------------------------------------------------------- */ /******************************************************************************* * Copyright (C) 2015 Maxim Integrated Products, Inc., All Rights Reserved. * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included * in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. * IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES * OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR * OTHER DEALINGS IN THE SOFTWARE. * * Except as contained in this notice, the name of Maxim Integrated * Products, Inc. shall not be used except as stated in the Maxim Integrated * Products, Inc. Branding Policy. * * The mere transfer of this software does not imply any licenses * of trade secrets, proprietary technology, copyrights, patents, * trademarks, maskwork rights, or any other form of intellectual * property whatsoever. Maxim Integrated Products, Inc. retains all * ownership rights. ******************************************************************************* */ #include "algorithm.h" #include "mbed.h" void maxim_heart_rate_and_oxygen_saturation(uint32_t *un_ir_buffer , int32_t n_ir_buffer_length, uint32_t *un_red_buffer , int32_t *n_spo2, int8_t *ch_spo2_valid , int32_t *n_heart_rate , int8_t *ch_hr_valid) /** * \brief Calculate the heart rate and SpO2 level * \par Details * By detecting peaks of PPG cycle and corresponding AC/DC of red/infra-red signal, the ratio for the SPO2 is computed. * Since this algorithm is aiming for Arm M0/M3. formaula for SPO2 did not achieve the accuracy due to register overflow. * Thus, accurate SPO2 is precalculated and save longo uch_spo2_table[] per each ratio. * * \param[in] *un_ir_buffer - IR sensor data buffer * \param[in] n_ir_buffer_length - IR sensor data buffer length * \param[in] *un_red_buffer - Red sensor data buffer * \param[out] *n_spo2 - Calculated SpO2 value * \param[out] *ch_spo2_valid - 1 if the calculated SpO2 value is valid * \param[out] *n_heart_rate - Calculated heart rate value * \param[out] *ch_hr_valid - 1 if the calculated heart rate value is valid * * \retval None */ { uint32_t irMean ,onlyOnce ; int32_t k ,iRatioCount; int32_t i,s ,m, exact_ir_valley_locs_count ,middleIdx; int32_t th1, n_npks,cMin; int32_t ir_valley_locs[15] ; int32_t exact_ir_valley_locs[15] ; int32_t dx_peak_locs[15] ; int32_t peakintervalSum; int32_t yAC, xAC; int32_t spo2calc; int32_t yDCmax, xDCmax; int32_t yDCmaxIdx, xDCmaxIdx; int32_t ratio[5],ratioAverage; int32_t nume, denom ; // remove DC of ir signal irMean =0; for (k=0 ; k<n_ir_buffer_length ; k++ ) irMean += un_ir_buffer[k] ; irMean =irMean/n_ir_buffer_length ; for (k=0 ; k<n_ir_buffer_length ; k++ ) n_x[k] = un_ir_buffer[k] - irMean ; // 4 pt Moving Average for(k=0; k< BUFFER_SIZE-MA4_SIZE; k++){ denom= ( n_x[k]+n_x[k+1]+ n_x[k+2]+ n_x[k+3]); n_x[k]= denom/(int32_t)4; } // get difference of smoothed IR signal for( k=0; k<BUFFER_SIZE-MA4_SIZE-1; k++) n_dx[k]= (n_x[k+1]- n_x[k]); // 2-pt Moving Average to n_dx for(k=0; k< BUFFER_SIZE-MA4_SIZE-2; k++){ n_dx[k] = ( n_dx[k]+n_dx[k+1])/2 ; } // hamming window // flip wave form so that we can detect valley with peak detector for ( i=0 ; i<BUFFER_SIZE-HAMMING_SIZE-MA4_SIZE-2 ;i++){ s= 0; for( k=i; k<i+ HAMMING_SIZE ;k++){ s -= n_dx[k] *uw_hamm[k-i] ; } n_dx[i]= s/ (int32_t)1146; // divide by sum of uw_hamm } th1=0; // threshold calculation for ( k=0 ; k<BUFFER_SIZE-HAMMING_SIZE ;k++){ th1 += ((n_dx[k]>0)? n_dx[k] : ((int32_t)0-n_dx[k])) ; } th1= th1/ ( BUFFER_SIZE-HAMMING_SIZE); // peak location is acutally index for sharpest location of raw signal since we flipped the signal maxim_find_peaks( dx_peak_locs, &n_npks, n_dx, BUFFER_SIZE-HAMMING_SIZE, th1, 8, 5 );//peak_height, peak_distance, max_num_peaks peakintervalSum =0; if (n_npks>=2){ for (k=1; k<n_npks; k++) peakintervalSum += (dx_peak_locs[k] -dx_peak_locs[k -1] ) ; peakintervalSum =peakintervalSum/(n_npks-1); *n_heart_rate =(int32_t)( 6000/ peakintervalSum );// beats per minutes //prlongf(">>> *n_heart_rate= %d \n", *n_heart_rate) ; *ch_hr_valid = 1; } else { *n_heart_rate = -999; *ch_hr_valid = 0; } for ( k=0 ; k<n_npks ;k++) ir_valley_locs[k]= dx_peak_locs[k] +HAMMING_SIZE /2; // raw value : RED(=y) and IR(=X) // we need to assess DC and AC value of ir and red PPG. for (k=0 ; k<n_ir_buffer_length ; k++ ) { n_x[k] = un_ir_buffer[k] ; n_y[k] = un_red_buffer[k] ; } // find precise min near ir_valley_locs exact_ir_valley_locs_count =0; for ( k=0 ; k<n_npks ;k++){ onlyOnce =1; m=ir_valley_locs[k]; cMin= 16777216;//2^24; if (m+5 < BUFFER_SIZE-HAMMING_SIZE && m-5 >0){ for(i= m-5;i<m+5; i++) if (n_x[i]<cMin){ if (onlyOnce >0){ onlyOnce =0; } cMin= n_x[i] ; exact_ir_valley_locs[k]=i; } if (onlyOnce ==0) exact_ir_valley_locs_count ++ ; } } if (exact_ir_valley_locs_count <2 ){ *n_spo2 = -999 ; // do not use SPO2 since signal ratio is out of range *ch_spo2_valid = 0; return; } // 4 pt MA for(k=0; k< BUFFER_SIZE-MA4_SIZE; k++){ n_x[k]=( n_x[k]+n_x[k+1]+ n_x[k+2]+ n_x[k+3])/(int32_t)4; n_y[k]=( n_y[k]+n_y[k+1]+ n_y[k+2]+ n_y[k+3])/(int32_t)4; } //using exact_ir_valley_locs , find ir-red DC andir-red AC for SPO2 calibration ratio //finding AC/DC maximum of raw ir * red between two valley locations ratioAverage =0; iRatioCount = 0; for(k=0; k< 5; k++) ratio[k]=0; for (k=0; k< exact_ir_valley_locs_count; k++){ if (exact_ir_valley_locs[k] > BUFFER_SIZE ){ *n_spo2 = -999 ; // do not use SPO2 since valley loc is out of range *ch_spo2_valid = 0; return; } } // find max between two valley locations // and use ratio betwen AC compoent of Ir & Red and DC compoent of Ir & Red for SPO2 for (k=0; k< exact_ir_valley_locs_count-1; k++){ yDCmax= -16777216 ; xDCmax= - 16777216; // printf("range=%d: %d\n ", exact_ir_valley_locs[k], exact_ir_valley_locs[k+1]); if (exact_ir_valley_locs[k+1]-exact_ir_valley_locs[k] >10){ for (i=exact_ir_valley_locs[k]; i< exact_ir_valley_locs[k+1]; i++){ if (n_x[i]> xDCmax) {xDCmax =n_x[i];xDCmaxIdx =i; } if (n_y[i]> yDCmax) {yDCmax =n_y[i];yDCmaxIdx=i;} } yAC= (n_y[exact_ir_valley_locs[k+1]] - n_y[exact_ir_valley_locs[k] ] )*(yDCmaxIdx -exact_ir_valley_locs[k]); //red yAC= n_y[exact_ir_valley_locs[k]] + yAC/ (exact_ir_valley_locs[k+1] - exact_ir_valley_locs[k]) ; yAC= n_y[yDCmaxIdx] - yAC; // subracting linear DC compoenents from raw xAC= (n_x[exact_ir_valley_locs[k+1]] - n_x[exact_ir_valley_locs[k] ] )*(xDCmaxIdx -exact_ir_valley_locs[k]); // ir xAC= n_x[exact_ir_valley_locs[k]] + xAC/ (exact_ir_valley_locs[k+1] - exact_ir_valley_locs[k]); xAC= n_x[yDCmaxIdx] - xAC; // subracting linear DC compoenents from raw nume=( yAC *xDCmax)>>7 ; //prepare X100 to preserve floating value denom= ( xAC *yDCmax)>>7; if (denom>0 && iRatioCount <5 && nume != 0) { ratio[iRatioCount]= (nume*100)/denom ; //formular is ( yAC *xDCmax) / ( xAC *yDCmax) ; iRatioCount++; } } // prlongf("ratio[%d]= %d exact_ir_valley_locs[k] =%d , exact_ir_valley_locs[%d] =%d \n",k, ratio[k] ,exact_ir_valley_locs[k] ,k+1, exact_ir_valley_locs[k+1] ) ; // prlongf("nume= %d ,denom= %d yAC = %d, xDCmax = %d, xAC= %d, yDCmax = %d\n",nume, denom, yAC ,xDCmax ,xAC ,yDCmax ); } maxim_sort_ascend(ratio, iRatioCount); middleIdx= iRatioCount/2; if (middleIdx >1) ratioAverage =( ratio[middleIdx-1] +ratio[middleIdx])/2; // use median else ratioAverage = ratio[middleIdx ]; if( ratioAverage>2 && ratioAverage <184){ spo2calc= uch_spo2_table[ratioAverage] ; *n_spo2 = spo2calc ; *ch_spo2_valid = 1;// float_SPO2 = -45.060*ratioAverage* ratioAverage/10000 + 30.354 *ratioAverage/100 + 94.845 ; // for comparison with table } else{ *n_spo2 = -999 ; // do not use SPO2 since signal ratio is out of range *ch_spo2_valid = 0; } } void maxim_find_peaks( int32_t *n_locs, int32_t *n_npks, int32_t *n_x, int32_t n_size, int32_t n_min_height, int32_t n_min_distance, int32_t n_max_num ) /** * \brief Find peaks * \par Details * Find at most MAX_NUM peaks above MIN_HEIGHT separated by at least MIN_DISTANCE * * \retval None */ { maxim_peaks_above_min_height( n_locs, n_npks, n_x, n_size, n_min_height ); maxim_remove_close_peaks( n_locs, n_npks, n_x, n_min_distance ); *n_npks = min( *n_npks, n_max_num ); } void maxim_peaks_above_min_height( int32_t *n_locs, int32_t *n_npks, int32_t *n_x, int32_t n_size, int32_t n_min_height ) /** * \brief Find peaks above n_min_height * \par Details * Find all peaks above MIN_HEIGHT * * \retval None */ { int32_t i = 1, width; *n_npks = 0; while (i < n_size-1){ if (n_x[i] > n_min_height && n_x[i] > n_x[i-1]){ // find left edge of potential peaks width = 1; while (i+width < n_size && n_x[i] == n_x[i+width]) // find flat peaks width++; if (n_x[i] > n_x[i+width] && (*n_npks) < 15 ){ // find right edge of peaks n_locs[(*n_npks)++] = i; // for flat peaks, peak location is left edge i += width+1; } else i += width; } else i++; } } void maxim_remove_close_peaks( int32_t *n_locs, int32_t *n_npks, int32_t *n_x, int32_t n_min_distance ) /** * \brief Remove peaks * \par Details * Remove peaks separated by less than MIN_DISTANCE * * \retval None */ { int32_t i, j, old_npks, dist; /* Order peaks from large to small */ maxim_sort_indices_descend( n_x, n_locs, *n_npks ); for ( i = -1; i < *n_npks; i++ ){ old_npks = *n_npks; *n_npks = i+1; for ( j = i+1; j < old_npks; j++ ){ dist = n_locs[j] - ( i == -1 ? -1 : n_locs[i] ); // lag-zero peak of autocorr is at index -1 if ( dist > n_min_distance || dist < -n_min_distance ) n_locs[(*n_npks)++] = n_locs[j]; } } // Resort indices longo ascending order maxim_sort_ascend( n_locs, *n_npks ); } void maxim_sort_ascend(int32_t *n_x, int32_t n_size) /** * \brief Sort array * \par Details * Sort array in ascending order (insertion sort algorithm) * * \retval None */ { int32_t i, j, temp; for (i = 1; i < n_size; i++) { temp = n_x[i]; for (j = i; j > 0 && temp < n_x[j-1]; j--) n_x[j] = n_x[j-1]; n_x[j] = temp; } } void maxim_sort_indices_descend( int32_t *n_x, int32_t *n_indx, int32_t n_size) /** * \brief Sort indices * \par Details * Sort indices according to descending order (insertion sort algorithm) * * \retval None */ { int32_t i, j, temp; for (i = 1; i < n_size; i++) { temp = n_indx[i]; for (j = i; j > 0 && n_x[temp] > n_x[n_indx[j-1]]; j--) n_indx[j] = n_indx[j-1]; n_indx[j] = temp; } }