Quote:
Originally posted by yaman
It sounds to me like you want to measure the intensity of the light returned? If so, read ahead, otherwise, skip this post.
Quite frankly, this is <i>impossible</i>.
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Actually, it is possible if you hook up a position encoded motor shaft to that little sensitivity adjustment doo-hicky on the back and using a successive approximation feedback loop to resolve each of the bits
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The algorithm would work like this: First you would set the doo-hicky to the 50% point using the motor. Then you would read the binary output of the sensor. This output, a one or a zero, is the most significant bit. If the bit is a one, you know that the value is between 50% and 100%, otherwise it's between 0% and 50%. For the sake of this explanation, assume the bit was a one. Now we know we can exclude the lower 50% of the possible values. So we now set the doo-hicky to 75% and read the sensor to see if the level is between 50% and 75% (a zero) or 75% and 100% (a one). This bit is the second to MSB. Now assume we got a zero which means the value is between 50% and 75%. So now we set the doo-hickey to 62.5%... Each time through the loop you get one more bits-worth of resolution.
At the heart of most analog to digital converters is a voltage comparator that's making a binary decision just like the optical sensor does. This is how successive approximation analog to digital converters work.
-Kevin