I want to test a distance measuring sensor: Sharp’s GP2Y0A21YK0F. Can I use the same program the one you used for the Sharp Infrared Arduino Sketch?

Thank you

You can get the number from the data sheet. Pick a handful of distances on the data sheet graph and multiply the distance by V, where V is indicated by the graph. Do this for a number of values along the range of distances and then average them to find an approximation.

In his case, you have:

30cm and 2V – 30×2=60
40cm and 1.5V – 40×1.5=60
60cm and 1V – 60×1=60
130cm and .5V – 130×0.5=65

(60+60+60+65)/4 = 61.25

In the ideal case, this number might provide a better estimate, but differences in individual sensors and environments will require adjustments to provide a better factor. Just go through that process to get a good starting point.

I’m not positive about this, but I believe the 65 in Larry’s equations is the slope of the graph, sort of. I believe it’s 1 over the slope times -1:
-1 * 1 / m
where m is the slope derived from
m = rise / run = (0.5 – 2.5)v / (150 – 20)cm = -2v / 130cm = -0.015384v/cm
so:
-1 * 1 / -0.015384v/cm = 65cm/v

That’s my assumption, but you know what happens when you make those

Thanks for posting this up. I’m still confused about how you got 65. I’m using a GP2D120 sensor and I’m trying to modify your code to that.
Please help.

Thanks,
ryder