GP2Y0A21YK With IOIO-OTG

[Marius Vosylius]

Im looking for solution, how to get Distance in CM using this SHARP GP2Y0A21YK sensor. Anyone have this implemented with IOIO?

https://www.sparkfun.com/products/242

[Al B]

AnalogInput _ir;

@Override
protected void setup() throws ConnectionLostException, InterruptedException {
..
...
   _ir = ioio_.openAnalogInput(40);
....
..
}

@Override
public void loop() throws ConnectionLostException {
..
....
   float value = _ir.getVoltage();
....
..
}

[Marius Vosylius]

Thanks AI B, this only will get me a voltage, but how I can covert it to distance in cm?

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[Al B]

In that case, then the datasheet is your best friend.

[Al B]

I meant this chart:

[Marius Vosylius]

Can you explain me how to use it, Im no actual Idea how programatically implement this chart. :(

[Ytai Ben-Tsvi]

Lookup table with linear interpolation?

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[Marius Vosylius]

More detail explanation please.

[Marius Vosylius]

http://www.acroname.com/articles/linearizing-sharp-ranger.html

Thats what I found, how can I Implement this:

x = (float) ((2914 / (irRange.getVoltage() + 5)) - 1); 

[Ytai Ben-Tsvi]

Cool. I think the units are wrong though.

Their "V" does not seem to be voltage, but rather "input from a 10-bit ADC" which can mean a lot of things but probably (5 / 1023) volts. They also mention that the output is linear, but not in actually meaningful distance units, so you should (empirically?) find the scaling factor for converting to your unit of choice.

[Al B]

This series may be helpful too.  Although uses MathLab-Simulink and targets Arduino; it could be applicable to the IOIO as well.

using-infrared-proximity-sensors-with-simulink

[Marius Vosylius]

http://oomlout.com/PROX/PROX-Guide.pdf

In this pdf shows how to convert reading from Voltage to CM, hopefully this one will work now.

[Al B]

So which equation did you end using?

A/D Reading to centimeters?
distance = 12343.85 * (10bit reading)^-1.15

or Voltage Reading to Centimeters?
distance = 27.86 (voltage reading)^-1.15