Hi All,
Arduino noob here! Mechanical Engineer looking to become an electronic engineer. I am currently building a device that measures differential pressure, temperature, SPo2 and heart rate of a person.
I am using
Arduino Uno
MLX 90614 for temperaure
MPX 5010 Dp for pressure
MAX30105 for spo2 and heart rate.
I based the code (attached) on the max30105 example as this was the largest and added the other bits into this.
My problem:
Individually each sketch works well but when I combine them I am not getting the same results as I was getting on the spo2 and Heart Rate monitor.
Is this due to code complications? There was a lot of playing around the placement of calls in the code in order to get the temperature sensor and pressure sensor to give similar results as I was seeing in their individual sketches.
Could it be to dyamic memory usage, I am at 91%, occasionally the code crashes, do I need a more power board?
Could it be from voltage interference/noise from the other sensors?
I am happy that all hardware connections are ok as I have been getting accurate data when I run the example code by its self, and until I added in the pressure sensor to the code.
#include <Wire.h>
#include "MAX30105.h"
#include "spo2_algorithm.h"
#include <Adafruit_MLX90614.h>
Adafruit_MLX90614 mlx = Adafruit_MLX90614(); //Temperature Sensot
MAX30105 particleSensor; // PPG Sensor
#define MAX_BRIGHTNESS 255 // PPG Sensor
#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
int sensorPin = A0; // Input from Pressure Sensor
int sensorValue = 0; //Set Sensor Value to 0
void setup()
{
Serial.begin(115200); // initialize serial communication at 115200 bits per second:
pinMode(pulseLED, 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);
}
pinMode(sensorPin, INPUT); // Pressure Sensor is on pin A0
mlx.begin(); // Temp Sensor Begin
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
}
//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 < 75; 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
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(" ")); // HR
Serial.print(heartRate, DEC);
Serial.print(F(" ")); //HR VAlid 1 = Valid, 0 = Not
Serial.print(validHeartRate, DEC);
Serial.print(F(" ")); // SPO2 Value
Serial.print(spo2, DEC);
Serial.print(F(" ")); // SPo2 Valid, 1 = Valid, 0 = Not
Serial.print(validSPO2, DEC);
Serial.print(F(" "));
Serial.print(mlx.readAmbientTempC(), 2); // Ambient Temp in C
Serial.print(F(" "));
Serial.print(mlx.readObjectTempC(), 2); // Object Temp in C
sensorValue = analogRead(sensorPin); // Reading from pressure sensor
Serial.print((" "));
Serial.println(sensorValue); // Pressure Sensor Analog Value, convert to KPA by mapping from 0-1023 ADC to 0-10000 Pa
}
//After gathering 25 new samples recalculate HR and SP02
maxim_heart_rate_and_oxygen_saturation(irBuffer, bufferLength, redBuffer, &spo2, &validSPO2, &heartRate, &validHeartRate);
}
}