Lighting PIC's forever.
This circuit shows how PIC12C508 can be used as e.g. a light
dimmer, or other light dependend things - using that the LED
conduct when it detects some light.
The LED seem to be very sensitive to light, and it is
possible to detect it, even when the light is "on" using that
the LED blinks very fast, and then detect when it is off.
In that way, will the circuit above be able to turn the LED
off or on, dependend on the light that it detects from its
surroundings.
No software aviable at the moment, but it is easy to make:
- The LED is connected to GP0 and GP1. When GP0 is high,
and GP1 is low, will it conduct, and emit light.
- When the GP0 is low, and GP1 is high, then the LED is
off. The LED is charged to -5V across it, and when the
GP1 turnes into three state, will it soon go low, and
the time depends on capacity and on current in LED.
Since, all messurements are made so that it not depend
on offset values here, will it be possible to detect
if the light increase or decrease. That means, that
the capacity, and the LED characteristic is unimportent.
- The time before GP1 turns low, is depend on the light
the LED detects. It have been choosen to let LED pull
GP1 low, and not threestate GP0 and pull it high. The
difference is the threeshold voltage of the input. And
detecting low voltage here gives higher voltage change.
And thereby also higher voltage swing, and high precision
compared with different input threeshold voltages. (If
the threeshold voltage is e.g. half, then it will only
take half time in opposite direction - here it is near
same time.)
- Using the light messurement methode above (on any pic)
makes it possible to messure the light by an LED.
Also, it is possible to let the LED turn on, or to make
it flash very fast, to make it seem as constant lighting here.
Typical the resistor will be choosen low, to make most
light out of the LED that may flash.
As you see, is it hereby possible to messure, and to
transmit using LED's. Any application that both recieve
light and emitts light is possible. That means, that e.g.
the PIC can adjust the light to be as small as possible, and
automatic turn it up if the surrounded light increases here.
Or it can be configurated using a CE version of the chips.
Another application is to have some light to hit the LED's,
and then when they are "touched" will they recieve dark.
This mean, that it is possible to detect which LED you
"touch" here.
And lot of other applications is possible.
I may add light sensitive application on my homepage, if noone
else do.
Links to light sensitive applications: