New answers tagged voltage
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Apparently all pins have enabled pull up/down resistors by default, listed in this document on page 102.
The pins I was using have a default pull-down setting, which explains the 2.7V at A given that the internal resistors are 50k.
I don't know how, but removing the default pull-down resistance solved my problem. Usually more advanced libraries have APIs ...
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did I do right? - NO
The values suggested (1kΩ/2kΩ) may be mathematically correct (assuming you could ACTUALLY get 2kΩ resistors) BUT ignore the reality of circuit design which needs to consider the tolerance of the external voltage, the resistor values and the input characteristics of the Pi.
An Engineer would design a circuit to provide ≥ 1.8V < 3.3V ...
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The post you link explains pretty well, but it does not explain how they selected the 2K resistor.
They do explain why, though. At the end of the question:
Since the Raspberry Pi GPIO PINs work with 3.3V, I had to build a voltage divider to convert the 5V output of the sensor to 3.3V. Assuming the left-most resistor on the breadboard is 2K ohm and the ...
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