Milone E tape sensor

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handrumsolo
 
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Milone E tape sensor

Post by handrumsolo »

etape modified.JPG
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Have a question about setting up the E-tape sensor with arduino. I want to setup a voltage divider circuit as seen in the tutorial (https://learn.adafruit.com/smart-measuring-cup/hardware) from contacting the manufacturer I understand the sensors sold through adafruit ( I have the 12 inch in the plastic case) are wired as follows
Red= Vin
Black =Gnd
White=Vout

Does this mean I only use the black wire from the etape (also black in the tutorial pic attached) to ground and the white wire from the etape (yellow in the tutorial pic) through the resistor and into analog input and can disregard the red wire from the etape (only used for temp compensation in a bridge config if I understand correctly)

Or...do I have the white and red flip flopped and can disregard the white?

Please advise.
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etape config.JPG
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adafruit_support_mike
 
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Re: Milone E tape sensor

Post by adafruit_support_mike »

You need all three wires.

The red and black wires provide the overall voltage for the divider. The white wire (or yellow in the Fritzing diagrams from the tutorial) shows how the sensor's resistance changes. That connects to an ADC pin.

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handrumsolo
 
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Re: Milone E tape sensor

Post by handrumsolo »

etape modified2.JPG
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Thanks for your quick reply. My confusion is that the diagram only shows two wires running out to the tape sensor and the etape documentation says just to use two pins. I uploaded a modified picture, I understand that the signal splits at the red circle with one path going through the yellow wire to the analog pin and the other going through the resistor and to the 5v pin but is the lead going back to the etape (that has the blue arrow pointing to it) the red or white one? Or are you saying I should splice the red and white together at the red circle?

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handrumsolo
 
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Re: Milone E tape sensor

Post by handrumsolo »

diagram.JPG
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After looking at what you said and this diagram I think I have answered my own question and that I use the red lead and ignore the white.

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adafruit_support_mike
 
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Re: Milone E tape sensor

Post by adafruit_support_mike »

Yes. The eTape sensor is basically a resistor. You connect one end to GND, and the other end to a pull-up resistor, then measure the voltage at the point where the pull-up and eTape meet.

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handrumsolo
 
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Re: Milone E tape sensor

Post by handrumsolo »

I gotthe etape sensor working using the code in this tutorial (https://learn.adafruit.com/smart-measuring-cup/hardware), however while the numbers seem to match exactly when im at max level, as the water level goes down, the numbers seem to get farther off. when im at 30cm on the tape its accurate but when i get down to 15cm im getting 13 something cm and when i go down to 10 cm its reading something cm. any idea as to what is going on here or is this just inherent in the sensor?

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