Oximeter 3 Click Board™

How Does The Oximeter 3 Click Board™ Work?

The Oximeter 3 Click Board™ is based on the VCNL4020C-GS08, a fully integrated biosensor and ambient light sensor with an I2C interface from Vishay Semiconductor. The VCNL4020C-GS08 sensor comes with a built-in infrared emitter, and signal processing IC in a single package with a 16 bit ADC. It also has an ambient light PIN photodiode with close-to-human-eye sensitivity with excellent ambient light suppression through signal modulation. For biosensor functionality, it converts the current from the PIN photodiode to a 16-bit digital data output value, while for the ambient light sensing it converts the current from the ambient light detector, amplifies it, and converts it to a 16-bit digital output stream.

The integrated infrared emitter has a peak wavelength of 890 nm. It emits light that reflects off an object within 20 cm of the sensor and has a programmable drive current from 10 mA to 200 mA in 10 mA steps. The built-in infrared emitter and broader sensitivity photodiode also can work with the additional on-board green LED and IRLED as designed on this Click board™. As an additional light source true green color LED (VLMTG1300) with a 525nm peak wavelength is used, alongside an infrared dual-color emitting diode (VSMD66694) with 660 nm and 940 nm peak wavelength well suited for measuring the optical pulse oximetry.

The PIN photodiode receives the light that is reflected off the object and converts it to a current. It has a peak sensitivity of 890 nm, matching the peak wavelength of the emitter, and it is insensitive to ambient light. The VCNL4020C also provides ambient light sensing to support conventional backlight and display brightness auto-adjustment. The ambient light sensor receives the visible light and converts it to a current, and it has peak sensitivity at 540 nm and bandwidth from 430 nm to 610 nm.

The Oximeter 3 Click Board™ communicates with the MCU using the standard I2C 2-wire interface with fixed slave address compatible with all I2C modes (Standard, Fast, and High-Speed). It allows easy access to a biosensor signal and light intensity measurements without complex calculations or programming. It also generates programmable interrupt signal routed on the INT pin of the mikroBUS™, that offers Wake-Up functionality for the MCU when a proximity event or ambient light change occurs, which reduces processing overhead by eliminating the need for continuous polling.

The Oximeter 3 Click Board™ is designed to be operated with both 3.3V and 5V logic voltage levels that can be selected via VCC SEL jumper. This allows for both 3.3V and 5V capable MCUs to use the I2C communication lines properly.

SPECIFICATIONS

PINOUT DIAGRAM

This table shows how the pinout of the Oximeter 3 Click Board™ corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
NC	1	AN	PWM	16	NC
NC	2	RST	INT	15	INT	Interrupt
NC	3	CS	RX	14	NC
NC	4	SCK	TX	13	NC
NC	5	MISO	SCL	12	SCL	I2C Clock
NC	6	MOSI	SDA	11	SDA	I2C Data
Power Supply	3.3V	7	3.3V	5V	10	5V	Power Supply
Ground	GND	8	GND	GND	9	GND	Ground

ONBOARD SETTINGS AND INDICATORS

OXIMETER 3 CLICK ELECTRICAL SPECIFICATIONS