123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379 |
- /** \file algorithm.cpp ******************************************************
- *
- * Project: MAXREFDES117#
- * Filename: algorithm.cpp
- * Description: This module calculates the heart rate/SpO2 level
- *
- *
- * --------------------------------------------------------------------
- *
- * This code follows the following naming conventions:
- *
- * char ch_pmod_value
- * char (array) s_pmod_s_string[16]
- * float f_pmod_value
- * int32_t n_pmod_value
- * int32_t (array) an_pmod_value[16]
- * int16_t w_pmod_value
- * int16_t (array) aw_pmod_value[16]
- * uint16_t uw_pmod_value
- * uint16_t (array) auw_pmod_value[16]
- * uint8_t uch_pmod_value
- * uint8_t (array) auch_pmod_buffer[16]
- * uint32_t un_pmod_value
- * int32_t * pn_pmod_value
- *
- * ------------------------------------------------------------------------- */
- /*******************************************************************************
- * Copyright (C) 2016 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"
- const uint16_t auw_hamm[31]={ 41, 276, 512, 276, 41 }; //Hamm= long16(512* hamming(5)');
- //uch_spo2_table is computed as -45.060*ratioAverage* ratioAverage + 30.354 *ratioAverage + 94.845 ;
- const uint8_t uch_spo2_table[184]={ 95, 95, 95, 96, 96, 96, 97, 97, 97, 97, 97, 98, 98, 98, 98, 98, 99, 99, 99, 99,
- 99, 99, 99, 99, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100,
- 100, 100, 100, 100, 99, 99, 99, 99, 99, 99, 99, 99, 98, 98, 98, 98, 98, 98, 97, 97,
- 97, 97, 96, 96, 96, 96, 95, 95, 95, 94, 94, 94, 93, 93, 93, 92, 92, 92, 91, 91,
- 90, 90, 89, 89, 89, 88, 88, 87, 87, 86, 86, 85, 85, 84, 84, 83, 82, 82, 81, 81,
- 80, 80, 79, 78, 78, 77, 76, 76, 75, 74, 74, 73, 72, 72, 71, 70, 69, 69, 68, 67,
- 66, 66, 65, 64, 63, 62, 62, 61, 60, 59, 58, 57, 56, 56, 55, 54, 53, 52, 51, 50,
- 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 31, 30, 29,
- 28, 27, 26, 25, 23, 22, 21, 20, 19, 17, 16, 15, 14, 12, 11, 10, 9, 7, 6, 5,
- 3, 2, 1 } ;
- static int32_t an_dx[ BUFFER_SIZE-MA4_SIZE]; // delta
- static int32_t an_x[ BUFFER_SIZE]; //ir
- static int32_t an_y[ BUFFER_SIZE]; //red
- void maxim_heart_rate_and_oxygen_saturation(uint32_t *pun_ir_buffer, int32_t n_ir_buffer_length, uint32_t *pun_red_buffer, int32_t *pn_spo2, int8_t *pch_spo2_valid,
- int32_t *pn_heart_rate, int8_t *pch_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] *pun_ir_buffer - IR sensor data buffer
- * \param[in] n_ir_buffer_length - IR sensor data buffer length
- * \param[in] *pun_red_buffer - Red sensor data buffer
- * \param[out] *pn_spo2 - Calculated SpO2 value
- * \param[out] *pch_spo2_valid - 1 if the calculated SpO2 value is valid
- * \param[out] *pn_heart_rate - Calculated heart rate value
- * \param[out] *pch_hr_valid - 1 if the calculated heart rate value is valid
- *
- * \retval None
- */
- {
- uint32_t un_ir_mean ,un_only_once ;
- int32_t k ,n_i_ratio_count;
- int32_t i, s, m, n_exact_ir_valley_locs_count ,n_middle_idx;
- int32_t n_th1, n_npks,n_c_min;
- int32_t an_ir_valley_locs[15] ;
- int32_t an_exact_ir_valley_locs[15] ;
- int32_t an_dx_peak_locs[15] ;
- int32_t n_peak_interval_sum;
-
- int32_t n_y_ac, n_x_ac;
- int32_t n_spo2_calc;
- int32_t n_y_dc_max, n_x_dc_max;
- int32_t n_y_dc_max_idx, n_x_dc_max_idx;
- int32_t an_ratio[5],n_ratio_average;
- int32_t n_nume, n_denom ;
- // remove DC of ir signal
- un_ir_mean =0;
- for (k=0 ; k<n_ir_buffer_length ; k++ ) un_ir_mean += pun_ir_buffer[k] ;
- un_ir_mean =un_ir_mean/n_ir_buffer_length ;
- for (k=0 ; k<n_ir_buffer_length ; k++ ) an_x[k] = pun_ir_buffer[k] - un_ir_mean ;
-
- // 4 pt Moving Average
- for(k=0; k< BUFFER_SIZE-MA4_SIZE; k++){
- n_denom= ( an_x[k]+an_x[k+1]+ an_x[k+2]+ an_x[k+3]);
- an_x[k]= n_denom/(int32_t)4;
- }
- // get difference of smoothed IR signal
-
- for( k=0; k<BUFFER_SIZE-MA4_SIZE-1; k++)
- an_dx[k]= (an_x[k+1]- an_x[k]);
- // 2-pt Moving Average to an_dx
- for(k=0; k< BUFFER_SIZE-MA4_SIZE-2; k++){
- an_dx[k] = ( an_dx[k]+an_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 -= an_dx[k] *auw_hamm[k-i] ;
- }
- an_dx[i]= s/ (int32_t)1146; // divide by sum of auw_hamm
- }
-
- n_th1=0; // threshold calculation
- for ( k=0 ; k<BUFFER_SIZE-HAMMING_SIZE ;k++){
- n_th1 += ((an_dx[k]>0)? an_dx[k] : ((int32_t)0-an_dx[k])) ;
- }
- n_th1= n_th1/ ( BUFFER_SIZE-HAMMING_SIZE);
- // peak location is acutally index for sharpest location of raw signal since we flipped the signal
- maxim_find_peaks( an_dx_peak_locs, &n_npks, an_dx, BUFFER_SIZE-HAMMING_SIZE, n_th1, 8, 5 );//peak_height, peak_distance, max_num_peaks
- n_peak_interval_sum =0;
- if (n_npks>=2){
- for (k=1; k<n_npks; k++)
- n_peak_interval_sum += (an_dx_peak_locs[k]-an_dx_peak_locs[k -1]);
- n_peak_interval_sum=n_peak_interval_sum/(n_npks-1);
- *pn_heart_rate=(int32_t)(6000/n_peak_interval_sum);// beats per minutes
- *pch_hr_valid = 1;
- }
- else {
- *pn_heart_rate = -999;
- *pch_hr_valid = 0;
- }
-
- for ( k=0 ; k<n_npks ;k++)
- an_ir_valley_locs[k]=an_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++ ) {
- an_x[k] = pun_ir_buffer[k] ;
- an_y[k] = pun_red_buffer[k] ;
- }
- // find precise min near an_ir_valley_locs
- n_exact_ir_valley_locs_count =0;
- for(k=0 ; k<n_npks ;k++){
- un_only_once =1;
- m=an_ir_valley_locs[k];
- n_c_min= 16777216;//2^24;
- if (m+5 < BUFFER_SIZE-HAMMING_SIZE && m-5 >0){
- for(i= m-5;i<m+5; i++)
- if (an_x[i]<n_c_min){
- if (un_only_once >0){
- un_only_once =0;
- }
- n_c_min= an_x[i] ;
- an_exact_ir_valley_locs[k]=i;
- }
- if (un_only_once ==0)
- n_exact_ir_valley_locs_count ++ ;
- }
- }
- if (n_exact_ir_valley_locs_count <2 ){
- *pn_spo2 = -999 ; // do not use SPO2 since signal ratio is out of range
- *pch_spo2_valid = 0;
- return;
- }
- // 4 pt MA
- for(k=0; k< BUFFER_SIZE-MA4_SIZE; k++){
- an_x[k]=( an_x[k]+an_x[k+1]+ an_x[k+2]+ an_x[k+3])/(int32_t)4;
- an_y[k]=( an_y[k]+an_y[k+1]+ an_y[k+2]+ an_y[k+3])/(int32_t)4;
- }
- //using an_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
- n_ratio_average =0;
- n_i_ratio_count =0;
-
- for(k=0; k< 5; k++) an_ratio[k]=0;
- for (k=0; k< n_exact_ir_valley_locs_count; k++){
- if (an_exact_ir_valley_locs[k] > BUFFER_SIZE ){
- *pn_spo2 = -999 ; // do not use SPO2 since valley loc is out of range
- *pch_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< n_exact_ir_valley_locs_count-1; k++){
- n_y_dc_max= -16777216 ;
- n_x_dc_max= - 16777216;
- if (an_exact_ir_valley_locs[k+1]-an_exact_ir_valley_locs[k] >10){
- for (i=an_exact_ir_valley_locs[k]; i< an_exact_ir_valley_locs[k+1]; i++){
- if (an_x[i]> n_x_dc_max) {n_x_dc_max =an_x[i];n_x_dc_max_idx =i; }
- if (an_y[i]> n_y_dc_max) {n_y_dc_max =an_y[i];n_y_dc_max_idx=i;}
- }
- n_y_ac= (an_y[an_exact_ir_valley_locs[k+1]] - an_y[an_exact_ir_valley_locs[k] ] )*(n_y_dc_max_idx -an_exact_ir_valley_locs[k]); //red
- n_y_ac= an_y[an_exact_ir_valley_locs[k]] + n_y_ac/ (an_exact_ir_valley_locs[k+1] - an_exact_ir_valley_locs[k]) ;
-
-
- n_y_ac= an_y[n_y_dc_max_idx] - n_y_ac; // subracting linear DC compoenents from raw
- n_x_ac= (an_x[an_exact_ir_valley_locs[k+1]] - an_x[an_exact_ir_valley_locs[k] ] )*(n_x_dc_max_idx -an_exact_ir_valley_locs[k]); // ir
- n_x_ac= an_x[an_exact_ir_valley_locs[k]] + n_x_ac/ (an_exact_ir_valley_locs[k+1] - an_exact_ir_valley_locs[k]);
- n_x_ac= an_x[n_y_dc_max_idx] - n_x_ac; // subracting linear DC compoenents from raw
- n_nume=( n_y_ac *n_x_dc_max)>>7 ; //prepare X100 to preserve floating value
- n_denom= ( n_x_ac *n_y_dc_max)>>7;
- if (n_denom>0 && n_i_ratio_count <5 && n_nume != 0)
- {
- an_ratio[n_i_ratio_count]= (n_nume*20)/n_denom ; //formular is ( n_y_ac *n_x_dc_max) / ( n_x_ac *n_y_dc_max) ;
- n_i_ratio_count++;
- }
- }
- }
- maxim_sort_ascend(an_ratio, n_i_ratio_count);
- n_middle_idx= n_i_ratio_count/2;
- if (n_middle_idx >1)
- n_ratio_average =( an_ratio[n_middle_idx-1] +an_ratio[n_middle_idx])/2; // use median
- else
- n_ratio_average = an_ratio[n_middle_idx ];
- if( n_ratio_average>2 && n_ratio_average <184){
- n_spo2_calc= uch_spo2_table[n_ratio_average] ;
- *pn_spo2 = n_spo2_calc ;
- *pch_spo2_valid = 1;// float_SPO2 = -45.060*n_ratio_average* n_ratio_average/10000 + 30.354 *n_ratio_average/100 + 94.845 ; // for comparison with table
- }
- else{
- *pn_spo2 = -999 ; // do not use SPO2 since signal ratio is out of range
- *pch_spo2_valid = 0;
- }
- }
- void maxim_find_peaks(int32_t *pn_locs, int32_t *pn_npks, int32_t *pn_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( pn_locs, pn_npks, pn_x, n_size, n_min_height );
- maxim_remove_close_peaks( pn_locs, pn_npks, pn_x, n_min_distance );
- *pn_npks = min( *pn_npks, n_max_num );
- }
- void maxim_peaks_above_min_height(int32_t *pn_locs, int32_t *pn_npks, int32_t *pn_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, n_width;
- *pn_npks = 0;
-
- while (i < n_size-1){
- if (pn_x[i] > n_min_height && pn_x[i] > pn_x[i-1]){ // find left edge of potential peaks
- n_width = 1;
- while (i+n_width < n_size && pn_x[i] == pn_x[i+n_width]) // find flat peaks
- n_width++;
- if (pn_x[i] > pn_x[i+n_width] && (*pn_npks) < 15 ){ // find right edge of peaks
- pn_locs[(*pn_npks)++] = i;
- // for flat peaks, peak location is left edge
- i += n_width+1;
- }
- else
- i += n_width;
- }
- else
- i++;
- }
- }
- void maxim_remove_close_peaks(int32_t *pn_locs, int32_t *pn_npks, int32_t *pn_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, n_old_npks, n_dist;
-
- /* Order peaks from large to small */
- maxim_sort_indices_descend( pn_x, pn_locs, *pn_npks );
- for ( i = -1; i < *pn_npks; i++ ){
- n_old_npks = *pn_npks;
- *pn_npks = i+1;
- for ( j = i+1; j < n_old_npks; j++ ){
- n_dist = pn_locs[j] - ( i == -1 ? -1 : pn_locs[i] ); // lag-zero peak of autocorr is at index -1
- if ( n_dist > n_min_distance || n_dist < -n_min_distance )
- pn_locs[(*pn_npks)++] = pn_locs[j];
- }
- }
- // Resort indices longo ascending order
- maxim_sort_ascend( pn_locs, *pn_npks );
- }
- void maxim_sort_ascend(int32_t *pn_x,int32_t n_size)
- /**
- * \brief Sort array
- * \par Details
- * Sort array in ascending order (insertion sort algorithm)
- *
- * \retval None
- */
- {
- int32_t i, j, n_temp;
- for (i = 1; i < n_size; i++) {
- n_temp = pn_x[i];
- for (j = i; j > 0 && n_temp < pn_x[j-1]; j--)
- pn_x[j] = pn_x[j-1];
- pn_x[j] = n_temp;
- }
- }
- void maxim_sort_indices_descend(int32_t *pn_x, int32_t *pn_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, n_temp;
- for (i = 1; i < n_size; i++) {
- n_temp = pn_indx[i];
- for (j = i; j > 0 && pn_x[n_temp] > pn_x[pn_indx[j-1]]; j--)
- pn_indx[j] = pn_indx[j-1];
- pn_indx[j] = n_temp;
- }
- }
|