SparkFun gator:particle Hookup Guide

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Hardware Overview

The gator:particle consists of 4 pads for power and data.

Contacts Direction Description
GND N/A Ground: Reference voltage and ground loop.
3.3V In Power: Provides 3.3V to board.
SDA Bi-directional Data: Data and commands are transmitted between the sensor and microcontroller.
SCL In Clock: The microcontroller provides the timing needed to communicate on the data line.

Power

The specified operating voltage for the MAX30102 is between 1.7V - 2V. For use with the gator:bit (v2) and micro:bit, you should provide 3.3V through the 3V3 and GND pads to keep the logic levels consistent; the 3.3V input is then regulated to 1.8V for the MAX30102.

Power Connections and LED
Power connection pads and power indication LED.

MAX30102

The MAX30102 is a high-sensitivity pulse oximeter and heart-rate sensor that communicates over an I2C bus. The MAX30102 uses both red and IR LEDs along with a very sensitive photodetector for pulse oximetry (SpO2), heart-rate (HR) monitoring, and particle (PM) detection. For the most part, users will only need to know I2C addresses to prevent address conflicts with other devices or sensors.

MAX30102 IC
MAX30102: HR and SpO2 sensor.

Here are some of the characteristics of the MAX30102 sensor from the datasheet:

Characteristic Range
Operating Voltage 1.8V to 2V
Supply Current Heart Rate and SpO2 Mode: 600 to 1200 µA
IR Only Mode: 600 to 1200 µA
Operating Temperature -40°C to 85°C
(ΣΔ) ADC Resolution: 15 to 18-bits (programmable)
Sampling Rate: 50 - 3200 sps (programmable)
IR LED LED Wavelength: 870 to 900 nm (avg. 880 nm)
Forward Voltage: 1.4V
Radiant Power: 6.5 mW
LED Driver Current: 0 to 50 mA (programmable)
Red LED LED Wavelength: 650 to 670 nm (avg. 660 nm)
Forward Voltage: 2.1V
Radiant Power: 9.8 mW
LED Driver Current: 0 to 50 mA (programmable)
Photodetector Spectral Range of Sensitivity: 600 to 900 nm
Radiant Sensitive Area: 1.36 mm2
I2C Address 0xAE - Write Address
0xAF - Read Address

What are Heart-Rate and Oxygen Saturation?

Heart-rate is the speed at which your heart pumps blood through your body. Pulse oximetry is a noninvasive method of determining saturation of oxygen in your blood. However, this is a peripheral measurement is not always a direct reflection of the arterial oxygen saturation (SaO2), but two are correlated enough for clinical purposes. There are a multitude of applications for these measurements; especially, in the medical field.

Here are some examples of studies using HR monitoring and pulse oximetry:

Here are additional resources on how the MAX30102 functions for HR detection and pulse oximetry:

Note: The MAX30102 can be used as a biosensor that for SpO2 and HR measurements on finger tips or earlobes. The sensor does need good contact with constant pressure against the epidermis for accurate results.

What are Particulates?

Particulate matter is the accumulation of matter (solid or liquid) in Earth's atmosphere. These particles vary in size, composition, and distribution. Their effects range from individual health on a microscopic scale to regional climate on a macroscopic scale. Particulate matter is also used in the food industry. Apiarist traditionally use bee smokers when harvesting honey. Smoking is also a method of flavoring and preserving meats and other products.

Here is a link to some experiments involving PM:

For more information on particulate matter and their detection, check out some of these resources:

Note: Particle detection is another application of the MAX30102. The sensor relies on the reflection and scattering of the red and IR light from particles to detect their presence.

I2C Connection

I2C is a communication protocol used to transfer data between controller and peripheral devices. It is a 2-wire connection consisting of SDA (data) and SCL (clock). The protocol is pretty well defined so it can be shared with multiple devices. This is beneficial for daisy chaining multiple devices together on a single bus. The primary thing users will need to watch out for is address conflicts (you can't have devices with the same address).

I2C Connection
I2C connection pads.