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I have motor which is rotating a shaft. I can rotate it only for 200 degrees so I am planning to use Hall sensors and magnets on shaft to determine upper and lower rotation limits. The catch is I don't want to waste two analog pins for this. So, what is the best way to connect two Hall sensors to single analog pin so I would know when one of the limits is reached and if it is upper or lower?

The Hall sensor which I use outputs 1.6 V without magnetic field and goes 1 V down or 1 V up when I bring magnet close other way around. Supply voltage is 3.3 V.

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  • \$\begingroup\$ Can you use hall switches and 2 digital pins instead? \$\endgroup\$
    – Drew
    Commented Dec 30, 2021 at 19:52
  • \$\begingroup\$ Also please provide a part number for the hall sensor you're using now. \$\endgroup\$
    – Drew
    Commented Dec 30, 2021 at 19:54
  • \$\begingroup\$ Hall sensor is AH3503 and I would like to use hall sensor rather than hall switch. \$\endgroup\$
    – andz
    Commented Dec 30, 2021 at 19:56
  • \$\begingroup\$ Well right off I can tell you that your supply voltage is too low. It needs to be at least 4.5V for that sensor. It may work somewhat below that but some aspect of it's performance is likely compromised, otherwise they would have specified a lower minimum voltage. \$\endgroup\$
    – Drew
    Commented Dec 30, 2021 at 20:02
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    \$\begingroup\$ "goes 1 V down or 1 V up when I bring magnet close other way around" - so why are you using 2 hall sensors? \$\endgroup\$
    – Bruce Abbott
    Commented Dec 30, 2021 at 22:24

1 Answer 1

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I suppose you can use one ADC input pin to get two results. Here is a brief diagram showing. Combine two analog signals into one. And use a operating amplifier to execute signal conditioning. Choose appropriate resistors to match ADC input requirement.

enter image description here

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