Heart rate 4 click carries the MAX30101 high-sensitivity pulse oximeter and heart-rate sensor from Maxim Integrated. The click is designed to run on either 3.3V or 5V power supply. It communicates with the target MCU over I2C interface, with additional functionality provided by INT pin on the mikroBUS™ line.

MAX30101 sensor features

The MAX30101 is an integrated pulse oximetry and heart-rate monitor module. It includes internal LEDs, photodetectors, optical elements, and low-noise electronics with ambient light rejection.

The MAX30101 integrates red, green, and IR (infrared) LED drivers to modulate LED pulses for SpO2 and HR measurements. The LED current can be programmed from 0 to 50mA with proper supply voltage.

The device includes a proximity function to save power and reduce visible light emission when the user’s finger is not on the sensor.

The MAX30101 has an on-chip temperature sensor for calibrating the temperature dependence of the SpO2 subsystem. The temperature sensor has an inherent resolution 0.0625°C.

Pulse oximetry or SpO2

Oxygen-saturated blood absorbs light differently than unsaturated blood. Pulse oximeters measure the oxygen saturation in one’s blood. Or to put it more precisely the percentage of hemoglobin molecules in blood that is saturated with oxygen.

In a healthy adult, this readings go from 94% to 100%.

How the sensor works

Since oxygen-saturated blood absorbs more infrared light than red light, and unsaturated blood absorbs more red light than infrared light, the SpO2 readings are calculated by the comparison of the amount of these two types of light.

It is best to use your finger for measurement.

The same sensor as Hexiwear

Did you know that this click carries the same sensor as Hexiwear? 

When you place your wrist or fingertip over the slit on Hexiwear, the MAX30101 sensor measures the light absorbance of pulsing blood through a photodetector and derives heart-rate info. Current firmware version is able to show rough estimates.

MikroPlot

You can use the MikroPlot visualization tool (Windows) to generate a graph from the data sent from the MCU.

A UART-USB connection is required.

Key features

• MAX30101 heart-rate sensor
  • Programmable Sample Rate and LED Current for Power Savings
  • Low-Power Heart-Rate Monitor (< 1mW)
  • Ultra-Low Shutdown Current (0.7µA, typ)
• I2C interface
• 3.3V or 5V power supply