Introduction
Wiring up a MAX30102 Module & WizFi360-EVB-Mini to Raspberry Pi Pico
Programming MAX30102 Module
Programming WizFi360-EVB-Mini
Setting up Blynk Application for IoT Pulse Oximeter

Published August 21, 2022 © MIT

WizFi360-EVB-Mini Pulse Oximeter Blynk BPM

I'll build a pulse oximeter using MAX30102 and WizFi360-EVB-Mini that will track the Blood Oxygen level and send the data via Wi-Fi.

BeginnerFull instructions provided2 hours252

WizFi360-EVB-Mini Pulse Oximeter Blynk BPM

Things used in this project

Hardware components

WIZnet WizFi360-EVB-Mini

Raspberry Pi Pico

Maxim Integrated MAX30102 High-Sensitivity Pulse Oximeter and Heart-Rate Sensor for Wearable Health

Jumper wires (generic)

Software apps and online services

Blynk

Arduino IDE

Story

Introduction

WizFi360-EVB-Mini Hardware Overview

Thanks to WIZnet for supporting this project with WizFi360-EVB-Mini Hardware.

WizFi360-EVB-Mini

This document describes WizFi360-EVB-Mini. WizFi360-EVB-Mini is a compact development board for experimenting, testing, and verification of WizFi360. WizFi360-EVB-Mini is the same form factor as the NodeMCU V2. WizFi360 is a low-cost and low-power consumption industrial-grade WiFi module. It is compatible with IEEE802.11 b/g/n standard and supports SoftAP, Station, and SoftAP+Station modes. The serial port baud rate can be up to 2Mbps, which can meet the requirement of various applications.

https://docs.wiznet.io/Product/Wi-Fi-Module/WizFi360/wizfi360_evb_mini

MAX30102

The MAX30102 is an integrated pulse oximeter and heart rate monitor Sensor. It integrates a red LED and an infrared LED, photoelectric detectors, optical devices, and low-noise electronic circuits with ambient light suppression. Standard I2C compatible communication interface can transfer the collected values to the WizFi360-EVB-Mini for heart rate and blood oxygen calculation.

Photo-dissolution method
Light transmittance is converted into an electrical signal

Wiring up a MAX30102 Module & WizFi360-EVB-Mini to Raspberry Pi Pico

Connect the VCC pin to the power supply, GND to GND.
Connect the SCL pin to the I2C clock pin and the SDA pin to the I2C data pin on Raspberry Pi Pico.

Connect the Vin pin to the power supply, GND to GND.
Connect the TXD1 pin to the IO9 pin and the RXD1 pin to the IO8 pin on Raspberry Pi Pico.

Programming MAX30102 Module

It is best to attach the sensor to your finger using a rubber band or Velcro. When you press your finger against the sensor it varies enough to cause the blood in your finger to flow differently which makes the sensor readings unstable.

Install the MAX30102 library from Sparkfun

Finger Presence:

We continuously print the delta values to find the difference

void loop()
{
  samplesTaken++;

  Serial.print("IR[");
  Serial.print(particleSensor.getIR());
  Serial.print("] Hz[");
  Serial.print((float)samplesTaken / ((millis() - startTime) / 1000.0), 2);
  Serial.print("]");

  long currentDelta = particleSensor.getIR() - unblockedValue;

  Serial.print(" delta[");
  Serial.print(currentDelta);
  Serial.print("]");

  if (currentDelta > (long)100)
  {
    Serial.print(" Something is there!");
  }

  Serial.println();
}

The Serial output is printed as shown.

1 / 2

Display Heartbeat Waveform

Display heartbeat diagram on the Arduino serial plotter. Click tool->Serial Plotter.

#include <Wire.h>
#include "MAX30105.h"

MAX30105 particleSensor;

void setup()
{
  Serial.begin(115200);
  Serial.println("Initializing...");

  // Initialize sensor
  if (!particleSensor.begin(Wire, I2C_SPEED_FAST)) //Use default I2C port, 400kHz speed
  {
    Serial.println("MAX30105 was not found. Please check wiring/power. ");
    while (1);
  }

  //Setup to sense a nice looking saw tooth on the plotter
  byte ledBrightness = 0x1F; //Options: 0=Off to 255=50mA
  byte sampleAverage = 8; //Options: 1, 2, 4, 8, 16, 32
  byte ledMode = 3; //Options: 1 = Red only, 2 = Red + IR, 3 = Red + IR + Green
  int sampleRate = 100; //Options: 50, 100, 200, 400, 800, 1000, 1600, 3200
  int pulseWidth = 411; //Options: 69, 118, 215, 411
  int adcRange = 4096; //Options: 2048, 4096, 8192, 16384

  particleSensor.setup(ledBrightness, sampleAverage, ledMode, sampleRate, pulseWidth, adcRange); //Configure sensor with these settings

  //Take an average of IR readings at power up
  const byte avgAmount = 64;
  long baseValue = 0;
  for (byte x = 0 ; x < avgAmount ; x++)
  {
    baseValue += particleSensor.getIR(); //Read the IR value
  }
  baseValue /= avgAmount;

  //Pre-populate the plotter so that the Y scale is close to IR values
  for (int x = 0 ; x < 500 ; x++)
    Serial.println(baseValue);
}

void loop()
{
  Serial.println(particleSensor.getIR()); //Send raw data to plotter
}

The waveform is plotted using the Serial plotter.

output

Heart-rate and SPO2 Measurement

Display the heart rate and SPO2 on Arduino serial monitor. The ideal heart rate(adult): 60～100 beats per minute and the ideal SPO2: 95~100.

{
      while (particleSensor.available() == false) //do we have new data?
        particleSensor.check(); //Check the sensor for new data

      digitalWrite(readLED, !digitalRead(readLED)); //Blink onboard LED with every data read

      redBuffer[i] = particleSensor.getRed();
      irBuffer[i] = particleSensor.getIR();
      particleSensor.nextSample(); //We're finished with this sample so move to next sample

      //send samples and calculation result to terminal program through UART
      Serial.print(F("red="));
      Serial.print(redBuffer[i], DEC);
      Serial.print(F(", ir="));
      Serial.print(irBuffer[i], DEC);

      Serial.print(F(", HR="));
      Serial.print(heartRate, DEC);

      Serial.print(F(", HRvalid="));
      Serial.print(validHeartRate, DEC);

      Serial.print(F(", SPO2="));
      Serial.print(spo2, DEC);

      Serial.print(F(", SPO2Valid="));
      Serial.println(validSPO2, DEC);
    }

Output

Complete codes are added on the code section at the end of the project blog. Do follow till the end to understand this project.

Programming WizFi360-EVB-Mini

We will programming the WizFi360-EVB-Mini using the AT commands. We will be using multiple serial ports to communicate with USB and with WizFi360-EVB-Mini.

Serial2.println("AT\r\n"); //Handshaking with WizFi360-EVB-Mini

The WizFi360-EVB-MIni responds to the AT commands as shown.

Now, we can send AT commands to the WizFi360-EVB-Mini as per the documentation. There are normal transmission mode and transparent mode in WizFi360. In case WizFi360 is Normal Command mode, WizFi360 executes AT command. Confirm Normal Command mode by inputting AT\r\n and returning \r\nOK\r\n. In case transparent mode, WizFi360 doesn't execute AT command. Only transmit and receive data with peer. If input is "+++", switch to normal command mode.

We had installed the WizFi360 and WiFiEsp library from Wiznet that connects the module to the WiFi and then to Blynk.

WizFi360 lib

Setting up Blynk Application for IoT Pulse Oximeter

Download the Blynk app (App Store,Google Play)
Get the Auth Token from the app
Import this library to Arduino IDE

Blynk lib

Set the DataStream as shown below

Update SSID, password, Device ID, Auth Token in the sketch and upload it to Arduino. The WizFi360 is now connected to my WiFi router.

Add the elements to the dashboard to make the UI. Now the device is ready to receive the data from Raspberry Pi using WizFi360. The Heart Rate, SpO2 and the finger presence data are sent to the Blynk Console and the devices connected to them.

Dashboard

Project Working

Resources

Code

WizFi360-EVB-Mini_Pulse_Oximeter_Blynk BPM.ino

/*************************************************************
 WizFi360-EVB-Mini Pulse Oximeter Blynk BPM

 By: Girish Khanna 
 
 Date: 08-08-2022
 *************************************************************/
#include <Wire.h>
#include "MAX30105.h"
#include "spo2_algorithm.h"

#include <ESP8266_Lib.h>
#include <BlynkSimpleShieldEsp8266.h>

// Template ID, Device Name and Auth Token are provided by the Blynk.Cloud
// See the Device Info tab, or Template settings
#define BLYNK_TEMPLATE_ID "TEMP"
#define BLYNK_DEVICE_NAME "Device"
#define BLYNK_AUTH_TOKEN "Token"

// Comment this out to disable prints and save space
#define BLYNK_PRINT Serial

MAX30105 particleSensor;

#define MAX_BRIGHTNESS 255

char auth[] = BLYNK_AUTH_TOKEN;

// Your WiFi credentials.
// Set password to "" for open networks.
char ssid[] = "SSID";
char pass[] = "Pass";

// Hardware Serial on Mega, Leonardo, Micro...
#define EspSerial Serial2

// or Software Serial on Uno, Nano...
//#include <SoftwareSerial.h>
//SoftwareSerial EspSerial(2, 3); // RX, TX

// Your ESP8266 baud rate:
#define ESP8266_BAUD 115200

ESP8266 wifi(&EspSerial);

#if defined(__AVR_ATmega328P__) || defined(__AVR_ATmega168__)
//Arduino Uno doesn't have enough SRAM to store 100 samples of IR led data and red led data in 32-bit format
//To solve this problem, 16-bit MSB of the sampled data will be truncated. Samples become 16-bit data.
uint16_t irBuffer[100]; //infrared LED sensor data
uint16_t redBuffer[100];  //red LED sensor data
#else
uint32_t irBuffer[100]; //infrared LED sensor data
uint32_t redBuffer[100];  //red LED sensor data
#endif

int32_t bufferLength; //data length
int32_t spo2; //SPO2 value
int8_t validSPO2; //indicator to show if the SPO2 calculation is valid
int32_t heartRate; //heart rate value
int8_t validHeartRate; //indicator to show if the heart rate calculation is valid

byte pulseLED = 11; //Must be on PWM pin
byte readLED = 13; //Blinks with each data read

BlynkTimer timer;

// This function sends Arduino's uptime every second to Virtual Pin 2.
void myTimerEvent()
{
  // You can send any value at any time.
  // Please don't send more that 10 values per second.
  Blynk.virtualWrite(V1, heartRate); //HR
  Blynk.virtualWrite(V2, millis() / 1000);
  Blynk.virtualWrite(V3, spo2); //SPO2
  Blynk.virtualWrite(V4, validHeartRate); //PRESENSE
  Blynk.virtualWrite(V5, "WiizFi360 HRM"); //TEXT1
}

void setup()
{
  // Debug console
  Serial.begin(115200);

  // Set ESP8266 baud rate
  EspSerial.begin(ESP8266_BAUD);
  delay(10);

  pinMode(pulseLED, OUTPUT);
  pinMode(readLED, OUTPUT);

  // Initialize sensor
  if (!particleSensor.begin(Wire, I2C_SPEED_FAST)) //Use default I2C port, 400kHz speed
  {
    Serial.println(F("MAX30105 was not found. Please check wiring/power."));
    while (1);
  }

  Serial.println(F("Attach sensor to finger with rubber band. Press any key to start conversion"));

  byte ledBrightness = 60; //Options: 0=Off to 255=50mA
  byte sampleAverage = 4; //Options: 1, 2, 4, 8, 16, 32
  byte ledMode = 2; //Options: 1 = Red only, 2 = Red + IR, 3 = Red + IR + Green
  byte sampleRate = 100; //Options: 50, 100, 200, 400, 800, 1000, 1600, 3200
  int pulseWidth = 411; //Options: 69, 118, 215, 411
  int adcRange = 4096; //Options: 2048, 4096, 8192, 16384

  Serial.println("Initializing...");
  particleSensor.setup(ledBrightness, sampleAverage, ledMode, sampleRate, pulseWidth, adcRange); //Configure sensor with these settings
  Blynk.begin(auth, wifi, ssid, pass);

  // Setup a function to be called every second
  timer.setInterval(1000L, myTimerEvent);
}

void loop()
{
  bufferLength = 100; //buffer length of 100 stores 4 seconds of samples running at 25sps

  //read the first 100 samples, and determine the signal range
  for (byte i = 0 ; i < bufferLength ; i++)
  {
    while (particleSensor.available() == false) //do we have new data?
      particleSensor.check(); //Check the sensor for new data

    redBuffer[i] = particleSensor.getRed();
    irBuffer[i] = particleSensor.getIR();
    particleSensor.nextSample(); //We're finished with this sample so move to next sample

    Serial.print(F("red="));
    Serial.print(redBuffer[i], DEC);
    Serial.print(F(", ir="));
    Serial.println(irBuffer[i], DEC);
  }

  //calculate heart rate and SpO2 after first 100 samples (first 4 seconds of samples)
  maxim_heart_rate_and_oxygen_saturation(irBuffer, bufferLength, redBuffer, &spo2, &validSPO2, &heartRate, &validHeartRate);

  //Continuously taking samples from MAX30102.  Heart rate and SpO2 are calculated every 1 second
  while (1)
  {
    //dumping the first 25 sets of samples in the memory and shift the last 75 sets of samples to the top
    for (byte i = 25; i < 100; i++)
    {
      redBuffer[i - 25] = redBuffer[i];
      irBuffer[i - 25] = irBuffer[i];
    }

    //take 25 sets of samples before calculating the heart rate.
    for (byte i = 75; i < 100; i++)
    {
      while (particleSensor.available() == false) //do we have new data?
        particleSensor.check(); //Check the sensor for new data

      digitalWrite(readLED, !digitalRead(readLED)); //Blink onboard LED with every data read

      redBuffer[i] = particleSensor.getRed();
      irBuffer[i] = particleSensor.getIR();
      particleSensor.nextSample(); //We're finished with this sample so move to next sample

      //send samples and calculation result to terminal program through UART
      Serial.print(F("red="));
      Serial.print(redBuffer[i], DEC);
      Serial.print(F(", ir="));
      Serial.print(irBuffer[i], DEC);

      Serial.print(F(", HR="));
      Serial.print(heartRate, DEC);

      Serial.print(F(", HRvalid="));
      Serial.print(validHeartRate, DEC);

      Serial.print(F(", SPO2="));
      Serial.print(spo2, DEC);

      Serial.print(F(", SPO2Valid="));
      Serial.println(validSPO2, DEC);
    }
    //After gathering 25 new samples recalculate HR and SP02
    maxim_heart_rate_and_oxygen_saturation(irBuffer, bufferLength, redBuffer, &spo2, &validSPO2, &heartRate, &validHeartRate);
  }
  
  Blynk.run();
  timer.run();
}

Credits

Girish Khanna

2 projects • 3 followers

Game Developer, Hobbyist and a Maker