MAXREFDES220

The MAXREFDES220 provides detailed design information for using Analog 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.

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