SparkFun gator:UV Hookup Guide

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Hardware Overview

The gator:UV 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 sensor.
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 VEML6070 is between 2.7V - 5.5V. 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.

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

VEML6070

The VEML6070 is a UV sensor that communicates over an I2C bus. The VEML6070 detects UVA radiation up to 328 mW/cm2 with a resolution of 5 µW/cm2. For the most part, users will only need to know I2C addresses to prevent address conflicts with other devices or sensors.

VEML6070 IC
VEML6070 UV sensor.

Here are some of the characteristics of the VEML6070 sensor from the datasheet:

Characteristic Range
Operating Voltage 2.7V to 5.5V
Supply Current 240 µA
UVA Detection up to 328 mW/cm2
UVA Resolution 5 µW/cm2/step
I2C Address 0x70 - Write Commands
0x73 - Read MSB of UV Data
0x71 - Read LSB of UV Data

performance chracteristics
Performance characteristics from the datasheet. Click to enlarge.

What is UVA Radiation?

UVA radiation is a specific part of the spectrum of the solar radiation from the Sun. UVA light has wavelengths between 320 nm and 400 nm. Approximately, 4.9% of all solar radiation that makes it to the surface of the Earth is UVA light. UVA rays are often associated with photoaging and the formation of skin cancer.

solar radiation penetration through atmosphere
Penetration of solar radiation through Earth's atmosphere (from VEML6070 App. Note). Click to enlarge.

For more details on UV radiation, check out these online resources:

Some experiments and related topics for UVA radiation:

I2C Connection

I2C is a communication protocol used to transfer data between master and slave 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.