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	gain	0 = H-Gain mode 1 = M-Gain mode 2 = L-Gain mode
	r1	Iout R1 resistance value, in ohms. Default value is set to 5600 ohms. Please, refer to the datasheet page 4 for more information about R1.
Datasheet

Notes

• The gain must be set according to the illuminance range to be measured (datasheet page 5) through pins 3 and 4.
• Once the gain is set, the programmer must set the gain property. By default the sensor expects an H-Gain setting.
• Adjust r1 value to your needs.
• Once the r1 is set, the programmer must set the r1 property. By default the sensor expects a r1 value of 5600 ohms.

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 BH1620FVC sensor to an external ADC (ADS1115) / channel 0
s = sensor.attach("BH1620FVC", adc.ADS1115, 0)

-- If your gain / r1 values differ from de default values uncomment the
-- following lines and set your values
-- s:set("gain", 0)
-- s:set("r1", 5600)

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

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