Atmel Xplained Evaluation Board ATXMEGAA3BU-XPLD ATXMEGAA3BU-XPLD Scheda Tecnica
Codici prodotto
ATXMEGAA3BU-XPLD
AVR1934
5
8413A-AVR-09/11
which has been linearized is fairly complex, the resulting temperature should only be
regarded as an approximation to the actual temperature.
regarded as an approximation to the actual temperature.
2.4 Ambient light sensor
An ambient light sensor in available on the Atmel
®
AVR
®
XMEGA
®
-A3BU Xplained,
which is sensitive to visible light, much like the human eye. A resistor is connected in
series with the light sensor providing a voltage proportional to the current passing
through the light sensor. An increasing current gives an increasing voltage across the
series resistor, and this voltage is measured using the XMEGA ADC. Table 2-2
shows the relationship between the ambient light in lux and the voltage measured.
The table also provides some indication of what the different lux values represent in
daily life.
series with the light sensor providing a voltage proportional to the current passing
through the light sensor. An increasing current gives an increasing voltage across the
series resistor, and this voltage is measured using the XMEGA ADC. Table 2-2
shows the relationship between the ambient light in lux and the voltage measured.
The table also provides some indication of what the different lux values represent in
daily life.
Table 2-2.
Illuminance and ADC input voltage
Illuminance [lux]
ADC input [V]
Illuminance scenario
1
1 0,0024
Full moon overhead at tropical
latitudes
latitudes
10 0,0243
20 0,0485
30 0,0728
40 0,0971
50 0,1213
Family
living
room
60 0,1456
70 0,1699
80 0,1941
Hallway/toilet
100
0,2426
Very dark overcast day
200 0,4853
300 0,7279
Office
lighting
400 0,9706
Office
lighting
500 1,2132
Office
lighting
600 1,4559
700 1,6985
800 1,9412
850 2,0625
Overcast
day
1
Data obtained from Wikipedia