(4/4) BPM (Pulse Sensor) and Pedometer (ADXL345 Accelerometer) Wearable Device with OLED Display

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Overview

Finally, We integrate all the three sensors into a one working mini-wearable project.

Hardware Used

Arduino Nano V3 (Robotdyn)

ADXL345 Accelerometer

128×64 0.96″ OLED Display

Pulse/Heart Beat Sensor

Jumper Wires

Breadboard

Software Used

Arduino IDE

Libraries Used

The libraries used will be the compilation of the previous libraries.

Application Description

To make this a mini-wearable project, we will switch from Uno R3 to a Nano. The components will work with 3.3V.

Set-up the Hardware

Code

#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <PulseSensorPlayground.h>
//PulseSensor
#define USE_ARDUINO_INTERRUPTS true    // Set-up low-level interrupts for most accurate BPM math.   

//OLED Display
#define OLED_RESET 4
Adafruit_SSD1306 display(OLED_RESET);
#if (SSD1306_LCDHEIGHT != 32)
#error("Height incorrect, please fix Adafruit_SSD1306.h!");
#endif

//Accelerometer
#define DEVICE (0x53)    //ADXL345 device address
#define TO_READ (6)        //num of bytes we are going to read each time (two bytes for each axis)

#define offsetX   -10.5       // OFFSET values
#define offsetY   -2.5
#define offsetZ   -4.5

#define gainX     257.5        // GAIN factors
#define gainY     254.5
#define gainZ     248.5

//Pulse Sensor Variables
PulseSensorPlayground pulseSensor;  // Creates an instance of the PulseSensorPlayground object called "pulseSensor"

const int PulseWire = 0;       // PulseSensor Analog WIRE connected to ANALOG PIN 0
int Threshold = 385;           // Determine which Signal to "count as a beat" and which to ignore.
                               // Use the "Gettting Started Project" to fine-tune Threshold Value beyond default setting.
                               // Otherwise leave the default "550" value. 
//Accelerometer Variables
byte buff[TO_READ] ;    //6 bytes buffer for saving data read from the device
char str[512];                      //string buffer to transform data before sending it to the serial port

int x,y,z, stepsStepped;

int xavg, yavg,zavg, steps=0, flag=0;
int xval[15]={0}, yval[15]={0}, zval[15]={0};
int threshhold = 60.0;


void setup()   {                
  Serial.begin(9600);
  Wire.begin();
  
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);  // initialize with the I2C addr 0x3C (for the 128x32)
  pulseSensor.analogInput(PulseWire);   
  pulseSensor.setThreshold(Threshold);   
  // init done
  
  //Turning on the ADXL345
  writeTo(DEVICE, 0x2D, 0);      
  writeTo(DEVICE, 0x2D, 16);
  writeTo(DEVICE, 0x2D, 8);

  if (pulseSensor.begin()) {
    Serial.println("Pulse Sensor Initialized...");  //This prints one time at Arduino power-up,  or on Arduino reset.  
  }
  // Show image buffer on the display hardware.
  // Since the buffer is intialized with an Adafruit splashscreen
  // internally, this will display the splashscreen.
  display.display();
  delay(2000);

  // Clear the buffer.
  display.clearDisplay();

}


void loop() {
  int regAddress = 0x32; //First axis-acceleration-data register on the ADXL345
  readFrom(DEVICE, regAddress, TO_READ, buff); //read the acceleration data from the ADXL345
  
  int myBPM = pulseSensor.getBeatsPerMinute();  // Calls function on our pulseSensor object that returns BPM as an "int".
                                               // "myBPM" hold this BPM value now.

  //each axis reading comes in 10 bit resolution, ie 2 bytes.  Least Significat Byte first!!
  //thus we are converting both bytes in to one int
  x = (((int)buff[1]) << 8) | buff[0];   
  y = (((int)buff[3])<< 8) | buff[2];
  z = (((int)buff[5]) << 8) | buff[4];
  
  stepsStepped = ArduinoPedometer();
 
  if (pulseSensor.sawStartOfBeat()) {          // Constantly test to see if "a beat happened". 
      display.setTextSize(1.2);
      display.setTextColor(WHITE);
      display.setCursor(0,0);
      display.println("Your BPM is: " + String(myBPM) );
      display.setCursor(0,10);
      display.println("You # Of steps are: " + String(stepsStepped));
      display.display(); 
      display.clearDisplay();
  } 
  delay(100);
  
}

//---------------- Functions
//Writes val to address register on device
void writeTo(int device, byte address, byte val) {
   Wire.beginTransmission(device); //start transmission to device 
   Wire.write(address);        // send register address
   Wire.write(val);        // send value to write
   Wire.endTransmission(); //end transmission
}

//reads num bytes starting from address register on device in to buff array
void readFrom(int device, byte address, int num, byte buff[]) {
  Wire.beginTransmission(device); //start transmission to device 
  Wire.write(address);        //sends address to read from
  Wire.endTransmission(); //end transmission
  
  Wire.beginTransmission(device); //start transmission to device
  Wire.requestFrom(device, num);    // request 6 bytes from device
  
  int i = 0;
  while(Wire.available())    //device may send less than requested (abnormal)
  { 
    buff[i] = Wire.read(); // receive a byte
    i++;
  }
  Wire.endTransmission(); //end transmission
}


//Get pedometer.

int ArduinoPedometer(){
    int acc=0;
    int totvect[15]={0};
    int totave[15]={0};
    int xaccl[15]={0};
    int yaccl[15]={0};
    int zaccl[15]={0};
    for (int i=0;i<15;i++)
    {
      xaccl[i]= x;
      delay(1);
      yaccl[i]= y;
      delay(1);
      zaccl[i]= z;
      delay(1);
      totvect[i] = sqrt(((xaccl[i]-xavg)* (xaccl[i]-xavg))+ ((yaccl[i] - yavg)*(yaccl[i] - yavg)) + ((zval[i] - zavg)*(zval[i] - zavg)));
      totave[i] = (totvect[i] + totvect[i-1]) / 2 ;
      delay(150);
  
      //cal steps 
      if (totave[i]>threshhold && flag==0)
      {
         steps=steps+1;
         flag=1;
      }
      else if (totave[i] > threshhold && flag==1)
      {
          //do nothing 
      }
      if (totave[i] <threshhold  && flag==1)
      {
        flag=0;
      }
     // Serial.print("steps=");
     // Serial.println(steps);
     return(steps);
    }
  delay(100); 
 }