Max - I'm not sure what the purpose was. The original documentation just says: "The SRF08 can be used as a light sensor." That type of sensor really isn't senstive enough to detect someone coming into a room,
@Duane: It's just for measuring ambient light. One of the I2C calls returns the value.
My knee-jerk reaction was that someone just happened to throw one on because they had it lying around ... after which it became part of the design.
But then I thought that they may have thought of using the sensor to detect someone coming into a room and activating the room's lights -- in which case they could use the ambient light level to decide whether or not to activate the main lights.
Very nice work Duane. I was curious about the modules and managed to find a data sheet on the SR-04 here. They do have some electronics on-board - from the photos they look like they might be just the US devices only on the board.
I have a couple of boxes of US TXs and Rxs - just the bare transducers. I'd thought of making something like this with them but for $3 it's just not worth it....
@Duane: I've been told that the accuracy of untrasonic distance measurement readings is a function of temperature, humidity, and atmospheric pressure.
This is probably overkill, but since I'm intending on making my robot a veritable cornucopia of sensors, I'm planning on (a) adding these and (b) seeing how the untrasonic readings varies under different conditions.
a) Are you doing this for your robot?
b) Do you have any advice with regard to these sensors?