Grove Sunlight Sensor with Si1145 and Arduino/Platform IO


For hydroponics systems, every plant has preferences on how long they want sunlight per day. Some are 12 hours and others are 8 hours. This time, we would like to measure UV-light, visible light, and infrared light and check the growth.

Seeed (a hardware company) provides a Grove – Sunlight sensor (weblink). So, I would like to show how this sunlight sensor can be developed with our hydroponics system.

screenshot_70.pngBasil Hydroponic System

Hardware Specification

This sunlight sensor comes with SI1145 from SiliconLabs. It is a reflectance-based infrared proximity, UV index, and ambient light sensor.

The interface with the hardware is I2C.


Software Guide

Platform IO has Grove – Sunlight Sensor library.


Useful Header file and APIs – Arduino IDE: File > Examples > Grove_Sunlight_Sensor>SI1145DEMO

  • Header File
    • SI114x.h
  • Object Instantiation
    • SI114X SI1145 = SI114X();
  •  APIs
    • SI1145.Begin()
    • SI1145.ReadVisible()
    • SI1145.ReadIR()
    • SI1145.ReadUV
      • real_UV = ((float)SI1145.ReadUV() / 100 )

Lab Test

This sensor can output three information

  1. Visible Light
  2. Infrared (IR) Sensor
  3. UV light index: UV in mW per area
    • 0 to 2: Low UV
    • 3 to 5: Moderate
    • 6 to 7: Hight
    • 8 to 10: Very High
    • 11 or more: Extreme

When just a room light is on,screenshot_96.png

When the hydroponic light is on,screenshot_88


Grove Sunlight Sensor wikipage: weblink


green scientist
Love travel, running, engineering, and gardening. Exploring new parks.

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