Protocentral MAX30205 Body Temperature Sensor Library

Arduino library for the Protocentral MAX30205 human body temperature sensor breakout board.

Don't have one? Buy it here

You can buy the Qwiic-compatible MAX30205 here.

The QWIIC-compatible ProtoCentral MAX30205 breakout board is a wearable human body temperature sensor that reads with an accuracy of +/-0.1 °C. This is a digital I2C-based sensor, so no external ADC is required.

This version of the board is round and designed to be directly wearable by exposing an aluminium surface. The aluminium-base PCB helps in easy thermal conduction so that most of the heat gets transferred to the sensor, resulting in more accurate readings. The top side of the PCB is encapsulated in clear epoxy resin to make it waterproof, and it uses a medical-grade, biocompatible, flexible cable that does not irritate the skin.

Features

• Digital I2C body temperature sensor — no external ADC needed
• High accuracy of +/-0.1 °C over the 37 °C to 39 °C range
• 16-bit resolution (1 LSB = 0.00390625 °C)
• Reads temperature in Celsius or Fahrenheit
• Automatic address scanning (0x48 / 0x49)
• Low-power shutdown mode (<3.5 µA)
• Works on any board with Wire (AVR, SAMD, ESP32, ESP8266, RP2040, STM32, and more)

Installation

Arduino Library Manager (Recommended)

1. Open the Arduino IDE
2. Go to Sketch → Include Library → Manage Libraries
3. Search for "Protocentral MAX30205"
4. Click Install

Manual Installation

1. Download or clone this repository
2. Copy it into your Arduino libraries folder (~/Documents/Arduino/libraries/)

Hardware Setup

Connect the breakout board to the Arduino as follows:

MAX30205 pin	Arduino connection	Pin function
Vin / 5V	Vin (3.3V also supported, change the solder jumper on the back; default is 5V)	Power supply
GND	GND	Ground
SDA	A4 (or the board's SDA pin)	Serial data
SCL	A5 (or the board's SCL pin)	Serial clock

Quick Start

#include <Wire.h>
#include "Protocentral_MAX30205.h"

MAX30205 tempSensor;

void setup() {
  Serial.begin(115200);
  Wire.begin();

  // Scan for the sensor at 0x48 / 0x49 until one is found
  while (!tempSensor.scanAvailableSensors()) {
    Serial.println("Couldn't find the temperature sensor, please connect the sensor.");
    delay(5000);
  }

  tempSensor.begin();   // Continuous conversion, active mode
}

void loop() {
  Serial.print(tempSensor.getTemperature(), 2);
  Serial.println(" C");
  delay(100);
}

Using a custom I2C bus or address

The constructor accepts an explicit I2C address and TwoWire instance:

MAX30205 tempSensor(MAX30205_ADDRESS2, Wire1);   // 0x48 on the Wire1 bus

API Reference

Constructor

MAX30205(uint8_t sensorAddress = MAX30205_ADDRESS1, TwoWire &wirePort = Wire)

Methods

Method	Description
begin()	Configure continuous conversion mode; returns true if the sensor responds
scanAvailableSensors()	Probe addresses 0x48 and 0x49, latch the one that responds; returns true if found
getTemperature()	Read the body temperature in degrees Celsius
getTemperatureF()	Read the body temperature in degrees Fahrenheit
shutdown()	Put the device into low-power shutdown mode
printRegisters()	Dump the register contents to Serial for debugging

Constants

Constant	Value	Description
MAX30205_ADDRESS1	0x49	Default I2C address
MAX30205_ADDRESS2	0x48	Alternate I2C address
MAX30205_RESOLUTION	0.00390625	Degrees Celsius per LSB

Examples

Example	Description
01-basic-temperature-reading	Print temperature in Celsius and Fahrenheit to the Serial Monitor
02-temperature-serial-plotter	Stream temperature to the Arduino Serial Plotter

Visualizing Output

Open the Arduino Serial Monitor (or Serial Plotter) at 115200 baud to view the readings.

Documentation

For further details, refer to the documentation on the MAX30205 breakout board.

License

This product is open source! Both our hardware and software are open source and licensed under the following licenses:

Hardware: Creative Commons Share-alike 4.0 International

Software: MIT License

Documentation: Creative Commons Share-alike 4.0 International

See LICENSE.md for the full license text.