How to Use MAX30100: Examples, Pinouts, and Specs

The MAX30100 is an integrated pulse oximetry and heart-rate monitor sensor solution. It combines two LEDs, a photodetector, optimized optics, and low-noise analog signal processing to detect pulse oximetry and heart-rate signals. The MAX30100 is widely used in wearable technology, fitness assistant devices, and medical monitoring equipment.

• Wearable devices for fitness tracking
• Health monitoring systems
• Smartwatches with vital signs monitoring
• Medical-grade pulse oximeters

• Power Supply: 1.8V to 3.3V
• Operating Temperature: -40°C to +85°C
• Communication Interface: I2C
• LED Wavelengths: 660nm (Red), 940nm (IR)

1. Power Supply: Connect the VIN pin to a 1.8V to 3.3V power source and GND to the ground.
2. I2C Communication: Connect SCL and SDA to the corresponding I2C clock and data lines on your microcontroller.
3. Interrupts: Optionally, connect the INT pin to an interrupt-capable GPIO pin on your microcontroller.
4. LEDs: The RD and IRD pins are internally connected to the LEDs. No external connection is required.

• Ensure that the power supply is stable and within the specified voltage range.
• Use pull-up resistors on the I2C lines as required by your microcontroller's I2C interface.
• Place the sensor close to the skin to get accurate readings.
• Avoid direct sunlight and other strong light sources that may interfere with the sensor readings.

#include <Wire.h>
#include "MAX30100_PulseOximeter.h"

PulseOximeter pox;
uint32_t tsLastReport = 0;

void setup() {
  Serial.begin(115200);
  if (!pox.begin()) {
    Serial.println("Failed to initialize pulse oximeter!");
    for(;;);
  } else {
    Serial.println("Pulse oximeter initialized.");
  }
}

void loop() {
  // Make sure to call update as fast as possible
  pox.update();
  if (millis() - tsLastReport > 1000) {
    Serial.print("Heart rate:");
    Serial.print(pox.getHeartRate());
    Serial.print("bpm / SpO2:");
    Serial.print(pox.getSpO2());
    Serial.println("%");

    tsLastReport = millis();
  }
}

Note: This example assumes the use of a MAX30100 library, which provides the PulseOximeter class and simplifies the interaction with the sensor.

• Inaccurate Readings: Ensure the sensor is properly placed on the skin and that there is no movement or external light interference.
• No Data on I2C: Check the connections and pull-up resistors on the I2C lines. Also, ensure that the correct I2C address is being used.

• Sensor Not Detected: Verify the power supply and I2C connections. Use an I2C scanner sketch to check if the sensor is detected on the bus.
• Fluctuating Readings: Stabilize the sensor placement and avoid direct light interference.

Q: Can the MAX30100 be used with a 5V system? A: While the MAX30100 operates at 1.8V to 3.3V, level shifters can be used for 5V systems.

Q: How can I improve the accuracy of the sensor? A: Ensure a snug fit against the skin, minimize motion, and avoid external light interference.

Q: What is the default I2C address of the MAX30100? A: The default I2C address is 0x57 (7-bit).

Q: How do I know if the MAX30100 is functioning correctly? A: Check for a stable heart rate and SpO2 reading. If the readings are erratic, review the sensor placement and circuit connections.