Remember when you were a kid and there was a birthday party at the pool and your parents totally embarrassed you by slathering you all over with sunscreen and you were all "MOM I HAVE ENOUGH SUNSCREEN" and she wouldn't listen? Well, if you had this UV Index sensor connected up to an Arduino you could have said "According to this calibrated SI1145 sensor from SiLabs,the UV index right now is 4.5 which means I do not need more sunscreen" and she would have been so impressed with your project that you could have spent more time splashing around.

The SI1145 is a new sensor from SiLabs with a calibrated UV sensing algorithm that can calculate UV Index. We took this outside a couple days and compared the calculated UV index with the news-reported index and found it was very accurate! It's a digital sensor that works over I2C so just about any microcontroller can use it. The sensor also has individual visible and IR sensing elements so you can measure just about any kind of light - we only wrote our library to printout the 'counts' rather than the calculate the exact values of IR and Visible light so if you need precision Lux measurement check out the TSL2561. If you're feeling really advanced, you can connect up an IR LED to the LED pin and use the basic proximity sensor capability that is in the SI1145 as well.

We wrapped this nice little sensor up on a PCB with level shifting and regulation circuitry so you can safely use it with 3 or 5V microcontrollers. If you are using an Arduino, we've got a lovely tutorial and library already written up with example code so you can quickly read sensor readings and the UV index in under 10 minutes. Each order comes with one fully assembled and tested PCB breakout and a small piece of header. You'll need to solder the header onto the PCB but it's fairly easy and takes only a few minutes even for a beginner.

Technical Details

SI1145 Details:
  • Datasheet
  • IR Sensor Spectrum: Wavelength: 550nm-1000nm (centered on 800)
  • Visible Light Sensor Spectrum: Wavelength: 400nm-800nm (centered on 530)
  • Voltage Supply: Power with 3-5VDC
  • Output Type: I2C address 0x60 (7-bit)
  • Operating Temperature: -40°C ~ 85°C
Breakout Dimensions:
  • 20mm x 18mm x 2mm / 0.8" x 0.7" x 0.08"
  • Weight: 1.4g

Learn

A tutorial to help you get started with the SI1145 light sensor

SI1145 Digital UV Index / IR / Visible Light Sensor [1777]

  • Brand: Adafruit
  • Product Code: ADA-1777
  • Reward Points: 10
  • Availability: 6
  • £13.13

  • Ex Tax: £10.95
  • Price in reward points: 200

Light Sensor - BH1750

Light Sensor - BH1750

£16.24

This is a BH1750 light intensity sensor breakout board with a 16 bit AD converter built-in which can ...

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UV Sensor (.Net Gadgeteer compatible)

UV Sensor (.Net Gadgeteer compatible)

£9.06

This UV Sensor uses the GUVA-S12SD chip which is suitable for detecting the UV raditation in ...

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Infra-Red Receiver (Grove)

Infra-Red Receiver (Grove)

£6.77

The Infrared Receiver is used to receive infrared signals and also used for remote control ...

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Light Sensor (Panel Mount) - Grove

Light Sensor (Panel Mount) - Grove

£4.07

Panel mount Light sensor module uses the GL5528 photoresistor to detect the light intensity of the ...

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LightSense Module (.NET Gadgeteer Compatible)

LightSense Module (.NET Gadgeteer Compatible)

£4.88

LightSense Module measures light intensity.

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UV Sensor - Grove

UV Sensor - Grove

£10.48

The Grove – UV Sensor is used for detecting the intensity of incident ultraviolet (UV) radiation.

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Light Sensor - BH1750 (.NET Gadgeteer Compatible)

Light Sensor - BH1750 (.NET Gadgeteer Compatible)

£15.56

This module carries a BH1750, which is a digital ambient light sensor with digital output in Lux ...

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UV Sensor - Xadow

UV Sensor - Xadow

£11.77

Xadow UV Sensor is suitable for measuring the UV radiation in sunlight.

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Light / Luminosity / Lux Digital Sensor Breakout - TSL2561 [439]

Light / Luminosity / Lux Digital Sensor Breakout - TSL2561 [439]

£6.90

The TSL2561 luminosity sensor is an advanced digital light sensor, ideal for use in a wide range of ...

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UV Light Analog Sensor Breakout - GUVA-S12SD [1918]

UV Light Analog Sensor Breakout - GUVA-S12SD [1918]

£9.06

It uses a UV photodiode, which can detect the 240-370nm range of light (which covers UVB and most ...

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Light Sensor - Grove

Light Sensor - Grove

£4.33

The Light sensor module uses the GL5528 photoresistor to detect the light intensity of the ...

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Luminance Sensor (Grove)

Luminance Sensor (Grove)

£7.46

Grove - Luminance Sensor using APDS-9002 as lumens Sensor, provides the linear transforms lumen ...

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FLORA UV Index Sensor - Si1145 Light Sensor [1981]

FLORA UV Index Sensor - Si1145 Light Sensor [1981]

£8.33

We took our popular SI1145 UV index sensor and cut out everything you don't need for using with a ...

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VEML6070 UV Index Sensor Breakout [2899]

VEML6070 UV Index Sensor Breakout [2899]

£9.17

he VEML6070 from Vishay has a true UV A light sensor and an I2C-controlled ADC that will take ...

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