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project-heart-rate-algorithm/License.ino

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+/* Copyright (C) 2021 Aravind Chowdary., All Rights Reserved.
+*
+* Permission is hereby granted, free of charge, to any person obtaining a
+* copy of this software and associated documentation files (the "Software"),
+* to deal in the Software without restriction, including without limitation
+* the rights to use, copy, modify, merge, publish, distribute, sublicense,
+* and/or sell copies of the Software, and to permit persons to whom the
+* Software is furnished to do so, subject to the following conditions:
+*
+* The above copyright notice and this permission notice shall be included
+* in all copies or substantial portions of the Software.
+*
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+* IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
+* OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+* OTHER DEALINGS IN THE SOFTWARE.
+*
+* Except as contained in this notice, the name of Maxim Integrated
+* Products, Inc. shall not be used except as stated in the Maxim Integrated
+* Products, Inc. Branding Policy.
+*
+* The mere transfer of this software does not imply any licenses
+* of trade secrets, proprietary technology, copyrights, patents,
+* trademarks, maskwork rights, or any other form of intellectual
+* property whatsoever. Maxim Integrated Products, Inc. retains all
+* ownership rights.
+* 
+*/

project-heart-rate-algorithm/project-heart-rate-algorithm.ino

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+#include <Wire.h>
+#include "MAX30105.h"
+#include "spo2_algorithm.h"
+
+MAX30105 particleSensor;
+
+#define MAX_BRIGHTNESS 255
+
+#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
+
+void setup()
+{
+  Serial.begin(115200); // initialize serial communication at 115200 bits per second:
+
+  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("0"));
+  while (Serial.available() == 0) ; //wait until user presses a key
+  Serial.read();
+
+  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
+
+  particleSensor.setup(ledBrightness, sampleAverage, ledMode, sampleRate, pulseWidth, adcRange); //Configure sensor with these settings
+}
+
+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);
+  }
+}