Renamed FS to FreqS because there is an overlap with the FS library.

Uncommented one line because it seems you had forgotten to do so.

Author: nocturnedence

src/spo2_algorithm.cpp

@@ -67,7 +67,7 @@ void maxim_heart_rate_and_oxygen_saturation(uint16_t *pun_ir_buffer, int32_t n_i
                 int32_t *pn_heart_rate, int8_t *pch_hr_valid)
 #else
 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)
+                int32_t *pn_heart_rate, int8_t *pch_hr_valid)
 #endif
 /**
 * \brief        Calculate the heart rate and SpO2 level
@@ -131,7 +131,7 @@ void maxim_heart_rate_and_oxygen_saturation(uint32_t *pun_ir_buffer, int32_t n_i
   if (n_npks>=2){
     for (k=1; k<n_npks; k++) n_peak_interval_sum += (an_ir_valley_locs[k] -an_ir_valley_locs[k -1] ) ;
     n_peak_interval_sum =n_peak_interval_sum/(n_npks-1);
-    *pn_heart_rate =(int32_t)( (FS*60)/ n_peak_interval_sum );
+    *pn_heart_rate =(int32_t)( (FreqS*60)/ n_peak_interval_sum );
     *pch_hr_valid  = 1;
   }
   else  { 

src/spo2_algorithm.h

@@ -64,8 +64,8 @@
 
 #include <Arduino.h>
 
-#define FS 25    //sampling frequency
-#define BUFFER_SIZE (FS * 4) 
+#define FreqS 25    //sampling frequency
+#define BUFFER_SIZE (FreqS * 4) 
 #define MA4_SIZE 4 // DONOT CHANGE
 //#define min(x,y) ((x) < (y) ? (x) : (y)) //Defined in Arduino.h