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? :)– Piotr KulaFeb 20, 2014 at 12:29
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Following which website? For sure if 0V is low and 3V is high, then 0.04V is low, the same as 0V!– francisFeb 20, 2014 at 13:12
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You'd need something like 2.6V to trigger a HIGH.– GerbenFeb 20, 2014 at 19:31
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2Is 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 BennettFeb 20, 2014 at 19:52
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2 Answers
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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@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. Feb 20, 2014 at 19:48
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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. Feb 20, 2014 at 19:50
Are we talking about digital input here? Then, 42 mV don't count as a high.
answered Feb 20, 2014 at 7:42
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1See specs. here: mosaic-industries.com/embedded-systems/microcontroller-projects/…– ssavecFeb 20, 2014 at 9:38
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42 mV counts as a high if the designer says it does. The question is not about whether or not the device is sending a signal, but how to configure the Pi to properly interpret that signal.– cjsApr 7, 2017 at 0:40