clarify VCC, wrt #1452 #753
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OttoWinter
reviewed
Sep 15, 2020
components/sensor/adc.rst
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| @@ -77,6 +77,10 @@ where you want to shut down the chip if the voltage is low when using a battery. | |||
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| To measure the VCC voltage, set ``pin:`` to ``VCC`` and make sure nothing is connected to the ``A0`` pin. | |||
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| .. note:: | |||
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| To avoid confusion: It measures the voltage at the chip, and not at the VCC pin of the board. It is usually static at 2.91V. | |||
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Maybe we can elaborate on at the chip more. This option measures the logic supply voltage to the chip (around 3.3V).
What I don't quite understand is why it would usually be "static at 2.91V". I don't see that here, and I suspect that depends on the power supply.
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i got the 2.91V on two different device models (nodemcuv2, d1_mini) with different power supplies (USB, 6V VCC).
i can do some more testing, but i'm also interested what your devices show.
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looks like a case of extrapolating from incomplete data. my ESP8285 (tuya power socket) reports slighly varying values around 3.46V.
jesserockz
approved these changes
Dec 20, 2020
This was referenced Jan 7, 2021
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Description:
Related issue (if applicable): fixes esphome/issues#1452