BH1721FVC SENSOR

About this

BH1721FVC is an digital Ambient Light Sensor IC for I2C bus interface.

Features:

• I2C bus Interface, Slave Address : "0100011"
• Spectral responsibility is approximately human eye response
• Illuminance to Digital Converter
• Wide range and High resolution. (1 – 65528 lx )
• Low Current by power down function
• 50Hz / 60Hz Light noise reject-function
• 1.8V Logic input interface
• No need any external parts
• Light source dependency is little. (ex. Incandescent Lamp. Fluorescent Lamp. Halogen Lamp. White LED. Sun Light)
• Small measurement variation (+/- 15%)

Specification

What		Comments
Identifier	BH1721FVC
Interface	I2C
Provides	illuminance	lux (*)
Properties	resolution	0 = Auto-Resolution Mode 1 = H-Resolution Mode 2 = L-Resolution Mode Default value is H-Resolution Mode
	calibration	Calibration data +/- lux
Datasheet

Notes

• The resolution must be set according to the illuminance range to be measured (datasheet page 5).
• The programmer can use the calibration property to correct sensor readings that may be influenced by the location of the sensor, such as when the sensor is mounted behind a protective glass.

Comments

(*)

lux	Surfaces illuminated by
0.0001	Moonless, overcast night sky (starlight)
0.002	Moonless clear night sky with airglow
0.05–0.36	Full moon on a clear night
3.4	Dark limit of civil twilight under a clear sky
20–50	Public areas with dark surroundings
50	Family living room lights
80	Office building hallway/toilet lighting
100	Very dark overcast day
320–500	Office lighting
400	Sunrise or sunset on a clear day
1000	Overcast day: typical TV studio lighting
10,000–25,000	Full daylight (not direct sun)
32,000–100,000	Direct sunlight

Code

-- Attach BH1721FVC sensor to I2C0
s = sensor.attach("BH1721FVC", i2c.I2C0, 0)

-- If your resolution / calibration values differ from de default values uncomment the
-- following lines and set your own values
-- s:set("resolution", 1)
-- s:set("calibration", 0)

while true do
  print(s:read("illuminance"))
  tmr.delayms(500)
end

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