Maxim Integrated
MBED firmware for MAXREFDES117 Heart Rate / SpO2 sensor. Tested on KL25Z, K64F, and MAX32600MBED#
Dependencies: mbed
Diff: algorithm/algorithm.cpp
- Revision:
- 3:7c0fb55eb3ff
- Parent:
- 2:560e76e77544
- Child:
- 4:5273ab1085ab
--- a/algorithm/algorithm.cpp Thu Apr 21 18:25:34 2016 +0000
+++ b/algorithm/algorithm.cpp Thu Apr 21 19:38:17 2016 +0000
@@ -62,8 +62,8 @@
#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)
+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
@@ -71,13 +71,13 @@
* 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] *pun_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
+* \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
*/
@@ -88,37 +88,37 @@
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 n_ir_valley_locs[15] ;
- int32_t n_exact_ir_valley_locs[15] ;
- int32_t n_dx_peak_locs[15] ;
+ 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 n_ratio[5],n_ratio_average;
+ 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 += un_ir_buffer[k] ;
+ 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++ ) n_x[k] = un_ir_buffer[k] - un_ir_mean ;
+ 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= ( n_x[k]+n_x[k+1]+ n_x[k+2]+ n_x[k+3]);
- n_x[k]= n_denom/(int32_t)4;
+ 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++)
- n_dx[k]= (n_x[k+1]- n_x[k]);
+ an_dx[k]= (an_x[k+1]- an_x[k]);
- // 2-pt Moving Average to n_dx
+ // 2-pt Moving Average to an_dx
for(k=0; k< BUFFER_SIZE-MA4_SIZE-2; k++){
- n_dx[k] = ( n_dx[k]+n_dx[k+1])/2 ;
+ an_dx[k] = ( an_dx[k]+an_dx[k+1])/2 ;
}
// hamming window
@@ -126,86 +126,86 @@
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] ;
+ s -= an_dx[k] *auw_hamm[k-i] ;
}
- n_dx[i]= s/ (int32_t)1146; // divide by sum of uw_hamm
+ 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 += ((n_dx[k]>0)? n_dx[k] : ((int32_t)0-n_dx[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( n_dx_peak_locs, &n_npks, n_dx, BUFFER_SIZE-HAMMING_SIZE, n_th1, 8, 5 );//peak_height, peak_distance, max_num_peaks
+ 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 += (n_dx_peak_locs[k] -n_dx_peak_locs[k -1] ) ;
+ 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);
- *n_heart_rate =(int32_t)( 6000/ n_peak_interval_sum );// beats per minutes
- //prlongf(">>> *n_heart_rate= %d \n", *n_heart_rate) ;
- *ch_hr_valid = 1;
+ *pn_heart_rate =(int32_t)( 6000/ n_peak_interval_sum );// beats per minutes
+ //prlongf(">>> *pn_heart_rate= %d \n", *pn_heart_rate) ;
+ *pch_hr_valid = 1;
}
else {
- *n_heart_rate = -999;
- *ch_hr_valid = 0;
+ *pn_heart_rate = -999;
+ *pch_hr_valid = 0;
}
for ( k=0 ; k<n_npks ;k++)
- n_ir_valley_locs[k]= n_dx_peak_locs[k] +HAMMING_SIZE /2;
+ 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++ ) {
- n_x[k] = un_ir_buffer[k] ;
- n_y[k] = un_red_buffer[k] ;
+ an_x[k] = pun_ir_buffer[k] ;
+ an_y[k] = pun_red_buffer[k] ;
}
- // find precise min near n_ir_valley_locs
+ // 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=n_ir_valley_locs[k];
+ 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 (n_x[i]<n_c_min){
+ if (an_x[i]<n_c_min){
if (un_only_once >0){
un_only_once =0;
}
- n_c_min= n_x[i] ;
- n_exact_ir_valley_locs[k]=i;
+ 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 ){
- *n_spo2 = -999 ; // do not use SPO2 since signal ratio is out of range
- *ch_spo2_valid = 0;
+ *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++){
- 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;
+ 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 n_exact_ir_valley_locs , find ir-red DC andir-red AC for SPO2 calibration ratio
+ //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++) n_ratio[k]=0;
+ for(k=0; k< 5; k++) an_ratio[k]=0;
for (k=0; k< n_exact_ir_valley_locs_count; k++){
- if (n_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;
+ 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;
}
}
@@ -215,58 +215,58 @@
for (k=0; k< n_exact_ir_valley_locs_count-1; k++){
n_y_dc_max= -16777216 ;
n_x_dc_max= - 16777216;
- // printf("range=%d: %d\n ", n_exact_ir_valley_locs[k], n_exact_ir_valley_locs[k+1]);
- if (n_exact_ir_valley_locs[k+1]-n_exact_ir_valley_locs[k] >10){
- for (i=n_exact_ir_valley_locs[k]; i< n_exact_ir_valley_locs[k+1]; i++){
+ // printf("range=%d: %d\n ", an_exact_ir_valley_locs[k], an_exact_ir_valley_locs[k+1]);
+ 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 (n_x[i]> n_x_dc_max) {n_x_dc_max =n_x[i];n_x_dc_max_idx =i; }
- if (n_y[i]> n_y_dc_max) {n_y_dc_max =n_y[i];n_y_dc_max_idx=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= (n_y[n_exact_ir_valley_locs[k+1]] - n_y[n_exact_ir_valley_locs[k] ] )*(n_y_dc_max_idx -n_exact_ir_valley_locs[k]); //red
- n_y_ac= n_y[n_exact_ir_valley_locs[k]] + n_y_ac/ (n_exact_ir_valley_locs[k+1] - n_exact_ir_valley_locs[k]) ;
+ 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= n_y[n_y_dc_max_idx] - n_y_ac; // subracting linear DC compoenents from raw
- n_x_ac= (n_x[n_exact_ir_valley_locs[k+1]] - n_x[n_exact_ir_valley_locs[k] ] )*(n_x_dc_max_idx -n_exact_ir_valley_locs[k]); // ir
- n_x_ac= n_x[n_exact_ir_valley_locs[k]] + n_x_ac/ (n_exact_ir_valley_locs[k+1] - n_exact_ir_valley_locs[k]);
- n_x_ac= n_x[n_y_dc_max_idx] - n_x_ac; // subracting linear DC compoenents from raw
+ 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)
{
- n_ratio[n_i_ratio_count]= (n_nume*100)/n_denom ; //formular is ( n_y_ac *n_x_dc_max) / ( n_x_ac *n_y_dc_max) ;
+ an_ratio[n_i_ratio_count]= (n_nume*100)/n_denom ; //formular is ( n_y_ac *n_x_dc_max) / ( n_x_ac *n_y_dc_max) ;
n_i_ratio_count++;
}
}
- // prlongf("n_ratio[%d]= %d n_exact_ir_valley_locs[k] =%d , n_exact_ir_valley_locs[%d] =%d \n",k, n_ratio[k] ,n_exact_ir_valley_locs[k] ,k+1, n_exact_ir_valley_locs[k+1] ) ;
+ // prlongf("an_ratio[%d]= %d an_exact_ir_valley_locs[k] =%d , an_exact_ir_valley_locs[%d] =%d \n",k, an_ratio[k] ,an_exact_ir_valley_locs[k] ,k+1, an_exact_ir_valley_locs[k+1] ) ;
// prlongf("n_nume= %d ,n_denom= %d n_y_ac = %d, n_x_dc_max = %d, n_x_ac= %d, n_y_dc_max = %d\n",n_nume, n_denom, n_y_ac ,n_x_dc_max ,n_x_ac ,n_y_dc_max );
}
- maxim_sort_ascend(n_ratio, 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 =( n_ratio[n_middle_idx-1] +n_ratio[n_middle_idx])/2; // use median
+ n_ratio_average =( an_ratio[n_middle_idx-1] +an_ratio[n_middle_idx])/2; // use median
else
- n_ratio_average = n_ratio[n_middle_idx ];
+ 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] ;
- *n_spo2 = n_spo2_calc ;
- *ch_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
+ *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{
- *n_spo2 = -999 ; // do not use SPO2 since signal ratio is out of range
- *ch_spo2_valid = 0;
+ *pn_spo2 = -999 ; // do not use SPO2 since signal ratio is out of range
+ *pch_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 )
+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
@@ -275,12 +275,12 @@
* \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 );
+ 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 *n_locs, int32_t *n_npks, int32_t *n_x, int32_t n_size, int32_t n_min_height )
+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
@@ -290,15 +290,15 @@
*/
{
int32_t i = 1, n_width;
- *n_npks = 0;
+ *pn_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
+ 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 && n_x[i] == n_x[i+n_width]) // find flat peaks
+ while (i+n_width < n_size && pn_x[i] == pn_x[i+n_width]) // find flat peaks
n_width++;
- if (n_x[i] > n_x[i+n_width] && (*n_npks) < 15 ){ // find right edge of peaks
- n_locs[(*n_npks)++] = i;
+ 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;
}
@@ -311,7 +311,7 @@
}
-void maxim_remove_close_peaks( int32_t *n_locs, int32_t *n_npks, int32_t *n_x, int32_t n_min_distance )
+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
@@ -324,23 +324,23 @@
int32_t i, j, n_old_npks, n_dist;
/* Order peaks from large to small */
- maxim_sort_indices_descend( n_x, n_locs, *n_npks );
+ maxim_sort_indices_descend( pn_x, pn_locs, *pn_npks );
- for ( i = -1; i < *n_npks; i++ ){
- n_old_npks = *n_npks;
- *n_npks = i+1;
+ 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 = n_locs[j] - ( i == -1 ? -1 : n_locs[i] ); // lag-zero peak of autocorr is at index -1
+ 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 )
- n_locs[(*n_npks)++] = n_locs[j];
+ pn_locs[(*pn_npks)++] = pn_locs[j];
}
}
// Resort indices longo ascending order
- maxim_sort_ascend( n_locs, *n_npks );
+ maxim_sort_ascend( pn_locs, *pn_npks );
}
-void maxim_sort_ascend(int32_t *n_x, int32_t n_size)
+void maxim_sort_ascend(int32_t *pn_x, int32_t n_size)
/**
* \brief Sort array
* \par Details
@@ -351,14 +351,14 @@
{
int32_t i, j, n_temp;
for (i = 1; i < n_size; i++) {
- n_temp = n_x[i];
- for (j = i; j > 0 && n_temp < n_x[j-1]; j--)
- n_x[j] = n_x[j-1];
- n_x[j] = n_temp;
+ 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 *n_x, int32_t *n_indx, int32_t n_size)
+void maxim_sort_indices_descend( int32_t *pn_x, int32_t *pn_indx, int32_t n_size)
/**
* \brief Sort indices
* \par Details
@@ -369,10 +369,10 @@
{
int32_t i, j, n_temp;
for (i = 1; i < n_size; i++) {
- n_temp = n_indx[i];
- for (j = i; j > 0 && n_x[n_temp] > n_x[n_indx[j-1]]; j--)
- n_indx[j] = n_indx[j-1];
- n_indx[j] = n_temp;
+ 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;
}
}