MAXREFDES220#: Finger Heart Rate and Pulse Oximeter Smart Sensor with Digital Signal Processing

The MAXREFDES220# reference design provides everything you need to quickly prototype your product to measure finger-based heart rate, blood oxygen saturation level (SpO2), and blood pressure trending (BPT).

The MAX30101 and the MAX32664 provide an integrated hardware and software solution for multiple finger-based applications. The MAX32664 firmware provides algorithm output.

A MAX32630FTHR is provided to emulate a host system for easy development.

Design files, firmware, and software can be found on the Design Resources tab. The board is also available for purchase.


  • MAX30101 Heart Rate Monitor and Pulse Oximeter
    • Tiny, 5.6mm × 3.3mm × 1.55mm 14-Pin Optical Module
    • Integrated Cover Glass for Optimal, Robust Performance
    • Ultra-Low Power Operation for Mobile Devices (<1mW)
    • Programmable Sample Rate and LED Current for Power Savings
    • High SNR (Signal-to-Noise) Ratio, >80dB (typ)
  • MAX32664 Sensor Hub
    • Maxim-Licensed Firmware for Complete Algorithmic Support of: 1) Finger Heart-Rate and Blood Oxygen Saturation Calculations or 2) BPT, Heart-Rate, and Blood Oxygen Saturation Calculations
    • Industry-Standard I2C Interface for Communication with Host Controller
    • Dedicated Bootloader Authenticates Secure Firmware Updates
  • 3-Axis Accelerometer
    • Provides Greater Accuracy
    • Compensates for Motion Artifacts
MAXREFDES220# System Board Enlarge+


The MAXREFDES220# provides detailed design information for using Maxim devices to quickly implement the measurement of heart rate, SpO2, and BPT using reflective photoplethysmography (PPG).

The MAX30101 operates from a 1.8V power supply and a separate 5.0V power supply for the internal LED. Many device parameters are configurable using the MAX32644. The module can be shut down through software with zero standby current, allowing the power rails to remain powered at all times.

MAXREFDES220# System Board Enlarge+

The MAX32664 is a small, low-cost, power-optimized sensor hub for finger-based applications using the MAX30101. The hub collects and processes the output of the PPG and accelerometer transparently through a dedicated I2C interface. A second, standard-mode I2C interface connects to the host through a dedicated command set. The MAX32664A version is for heart rate and SpO2, whereas the MAX32664D version is a superset of the MAX32664A with an added BPT feature. The MAXREFDES220# can be programmed to accommodate either of the versions.

A Windows®-based GUI configures the sensors and graphically displays raw and processed heart-rate and SpO2 data. It also provides the ability to collect and log sensor output for offline evaluation. The MAXREFDES220# may also be reprogrammed with the BPT, heart rate, and SpO2 firmware, and an Android app is used to display those results.

The included MAX32630FTHR board emulates a host system for easy development. Source code for the MAX32630FTHR firmware is available on the Arm® Mbed site to allow customers to implement their own custom host on any platform.

As with all Maxim reference designs, the bill of materials (BOM), schematics, layout files, Gerber files, firmware, and software are all available online.

System Diagram

The MAXREFDES220# reference design block diagram.

Trademarks list

  • Android is a registered trademark of Google Inc.
  • Arm is a registered trademark of Arm Limited.
  • IOS is a registered trademark of Cisco Technology, Inc. and is under license to Apple Inc.
  • Mbed is a trademark of Arm Limited.
  • Windows is a registered trademark of Microsoft Corporation.

Ultra-Low Power Biometric Sensor Hub

  • Biometric Sensor Hub Enables Faster Time to Market
  • Finger-Based (Version A) Algorithms Measure
  • Wrist-Based (Version B) Algorithm Measures:

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

  • Heart-Rate Monitor and Pulse Oximeter Sensor in LED Reflective Solution
  • Tiny 5.6mm × 3.3mm × 1.55mm 14-Pin Optical Module
  • Ultra-Low Power Operation for Mobile Devices