IoT on Your Raspberry Pi

Grove SI1145 Sunlight Sensor

The Grove Sunlight Sensor I2C device is a multichannel digital light sensor and UV detector that can monitor sunlight (lumens), infrared (IR; lumens), and ultraviolet (UV; UV index), all in one board (Figures 6 and 7). The device is based on SI1145, a low-power reflectance-based sensor from SiLabs with an I2C digital interface and programmable event interrupt output. This device offers excellent performance under a wide dynamic range and a variety of light sources, including direct sunlight.

Figure 6: Grove Sunlight Sensor.
Figure 7: Visible and IR overlap.

The lumen (lm) is the SI unit of luminous flux, a measure of the total "amount" of visible light emitted by a source. Luminous flux differs from power (radiant flux), in that luminous flux measurements reflect the varying sensitivity of the human eye to different wavelengths of light, whereas radiant flux measurements indicate the total power of all electromagnetic waves emitted, independent of the eye's ability to perceive them. Lumens are related to illuminance, measured in lux (lx), by 1 lx = 1 lm/sq m. Table 1 lists some common illuminance examples.

Table 1



Lux (lm/sq m)

Dark night


Moonlit night


Cloudy day indoor


Cloudy day outdoor


Sunny day indoor


Suitable for reading


Home video camera


Grove LED

The Grove LED board (Figure 8) is very simple. It connects to a Digital Grove connector and turns its LED on when the digital input is high and off when the input is low. An on-board potentiometer lets you adjust the brightness of the LED.

Figure 8: Grove LED module.

Buy this article as PDF

Express-Checkout as PDF

Pages: 6

Price $2.95
(incl. VAT)

Buy Raspberry Pi Geek

Get it on Google Play

US / Canada

Get it on Google Play

UK / Australia

Related content