Diff: main.cpp

Revision:

1:83ace7df2c63

Parent:

0:0c37474c8541

--- a/main.cpp	Wed Apr 20 14:01:36 2016 +0000
+++ b/main.cpp	Mon Apr 16 16:52:36 2018 +0000
@@ -1,13 +1,127 @@
-/* See 
- * http://lancaster-university.github.io/microbit-docs/advanced/ 
- * for docs about using the micro:bit library
-*/
 #include "MicroBit.h"
+#include "MAX30102.h"
+#include "algorithm.h"
+
+MAX30102 sensor(I2C_SDA0, I2C_SCL0);
 
 MicroBitDisplay display;
 
+DigitalIn INT(P0_16);
+
+Serial pc(USBTX, USBRX);
+
+#define MAX_BRIGHTNESS 255
+
+uint32_t aun_ir_buffer[500]; //IR LED sensor data
+int32_t n_ir_buffer_length;    //data length
+uint32_t aun_red_buffer[500];    //Red LED sensor data
+int32_t n_sp02; //SPO2 value
+int8_t ch_spo2_valid;   //indicator to show if the SP02 calculation is valid
+int32_t n_heart_rate;   //heart rate value
+int8_t  ch_hr_valid;    //indicator to show if the heart rate calculation is valid
+uint8_t uch_dummy;
+
 int main()
 {
+    uint32_t un_min, un_max, un_prev_data;  //variables to calculate the on-board LED brightness that reflects the heartbeats
+    int i;
+    int32_t n_brightness;
+    float f_temp;
+    
+    sensor.reset();
+    sensor.init();
+    
+    n_brightness=0;
+    un_min=0x3FFFF;
+    un_max=0;
+    
+    pc.printf("Start\r\n");
+    
+    n_ir_buffer_length=500; //buffer length of 100 stores 5 seconds of samples running at 100sps
+    
+    //read the first 500 samples, and determine the signal range
+    //for(i=0;i<n_ir_buffer_length;i++)
+    i=0;
     while(1)
-        display.scroll(":)");
+    {
+        while(INT.read()==1);   //wait until the interrupt pin asserts
+        
+        sensor.read_fifo((aun_red_buffer+i), (aun_ir_buffer+i));  //read from MAX30102 FIFO
+            
+        if(un_min>aun_red_buffer[i])
+            un_min=aun_red_buffer[i];    //update signal min
+        if(un_max<aun_red_buffer[i])
+            un_max=aun_red_buffer[i];    //update signal max
+        pc.printf("red=");
+        pc.printf("%i", aun_red_buffer[i]);
+        pc.printf(", ir=");
+        pc.printf("%i\n\r", aun_ir_buffer[i]);
+    }
+    un_prev_data=aun_red_buffer[i];
+    
+    
+    //calculate heart rate and SpO2 after first 500 samples (first 5 seconds of samples)
+    maxim_heart_rate_and_oxygen_saturation(aun_ir_buffer, n_ir_buffer_length, aun_red_buffer, &n_sp02, &ch_spo2_valid, &n_heart_rate, &ch_hr_valid); 
+    
+    //Continuously taking samples from MAX30102.  Heart rate and SpO2 are calculated every 1 second
+    while(1)
+    {
+        i=0;
+        un_min=0x3FFFF;
+        un_max=0;
+        
+        //dumping the first 100 sets of samples in the memory and shift the last 400 sets of samples to the top
+        for(i=100;i<500;i++)
+        {
+            aun_red_buffer[i-100]=aun_red_buffer[i];
+            aun_ir_buffer[i-100]=aun_ir_buffer[i];
+            
+            //update the signal min and max
+            if(un_min>aun_red_buffer[i])
+            un_min=aun_red_buffer[i];
+            if(un_max<aun_red_buffer[i])
+            un_max=aun_red_buffer[i];
+        }
+        
+        //take 100 sets of samples before calculating the heart rate.
+        for(i=400;i<500;i++)
+        {
+            un_prev_data=aun_red_buffer[i-1];
+            while(INT.read()==1);
+            sensor.read_fifo((aun_red_buffer+i), (aun_ir_buffer+i));
+        
+            if(aun_red_buffer[i]>un_prev_data)
+            {
+                f_temp=aun_red_buffer[i]-un_prev_data;
+                f_temp/=(un_max-un_min);
+                f_temp*=MAX_BRIGHTNESS;
+                n_brightness-=(int)f_temp;
+                if(n_brightness<0)
+                    n_brightness=0;
+            }
+            else
+            {
+                f_temp=un_prev_data-aun_red_buffer[i];
+                f_temp/=(un_max-un_min);
+                f_temp*=MAX_BRIGHTNESS;
+                n_brightness+=(int)f_temp;
+                if(n_brightness>MAX_BRIGHTNESS)
+                    n_brightness=MAX_BRIGHTNESS;
+            }
+
+            //send samples and calculation result to terminal program through UART
+            pc.printf("red=");
+            pc.printf("%i", aun_red_buffer[i]);
+            pc.printf(", ir=");
+            pc.printf("%i", aun_ir_buffer[i]);
+            pc.printf(", HR=%i, ", n_heart_rate); 
+            pc.printf("HRvalid=%i, ", ch_hr_valid);
+            pc.printf("SpO2=%i, ", n_sp02);
+            pc.printf("SPO2Valid=%i\n\r", ch_spo2_valid);
+        }
+        maxim_heart_rate_and_oxygen_saturation(aun_ir_buffer, n_ir_buffer_length, aun_red_buffer, &n_sp02, &ch_spo2_valid, &n_heart_rate, &ch_hr_valid); 
+    }
+    
+    //while(1)
+    //    display.scroll(":)");
 }
\ No newline at end of file