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Im following this website using a different sensor and my output is too low for the GPIO so i don't know whether it effects anything as the program could not work.Can a raspberry pi accept input data if the input voltage is 42 mv when is required is 3.3v?So is it too low that it does not detect any input from the sensor?

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What sensor outputs data at 0.042volts? What is the input voltage? What is this sensor? :) –  ppumkin Feb 20 at 12:29
    
Following which website? For sure if 0V is low and 3V is high, then 0.04V is low, the same as 0V! –  francis Feb 20 at 13:12
    
You'd need something like 2.6V to trigger a HIGH. –  Gerben Feb 20 at 19:31
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Is the 42 mV a logic high for this sensor? If so, what is a logic low? Does the thing have an open collector output? In that case, you just need a pull-up resistor to 3.3 volts to get a proper high level. More details on the sensor are required. –  Peter Bennett Feb 20 at 19:52

2 Answers 2

To elaborate a little bit and provide a possible solution to the issue - you could use a transistor with the collector attached to the 3v3 outlet of the Pi, the emitter attached to your sensing GPIO and the base attached to your sensor. That way, the sensor will trigger the transistor 'on' with 0.042V, allowing current to flow from the 3v3 to the GPIO and producing the desired result

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with resistors, yeah. –  francis Feb 20 at 13:13
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Depends on what transistor you use –  exantas Feb 20 at 13:23
    
@exantas: you are suggesting an emitter follower - an emitter follower has the emitter about 0.7 volts below the base, so won't help here. I think the OP has to tell us what the sensor is before anyone can give useful advice. –  Peter Bennett Feb 20 at 19:48
    
Is the 42 mV a logic high for this sensor? If so, what is a logic low? Does the thing have an open collector output? In that case, you just need a pull-up resistor to 3.3 volts to get a proper high level. More details on the sensor are required. –  Peter Bennett Feb 20 at 19:50

Are we talking about digital input here? Then, 42 mV don't count as a high.

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Ya its digital input thnx. –  Milla Kurtney Feb 20 at 8:38
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