LDR SENSOR

Specification

What		Comments
Identifier	LDR
Interface	ADC
Provides	illuminance	lux (*)
Properties	R1 R2	R1 resistance in ohms (**) R2 resistance in ohms (**) If R1=0, LDR is on R1 If R2=0, LDR is on R2 Default R1 = 10.000 ohms Default R2 = 0 ohms

(*)

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

(**)

LDR component must be part of a voltage divider circuit:

LDR can be placed in the R1 location and R2 is a fixed-value register, or in the R2 location and R1 is a fixed-value register.

Typically the fixed-value register is 10K = 10.000 ohms.

Sensor default values are R1 = 10.000 ohms / R2 = 0 ohms.

Code