Voltage range of ADC is at the chip pin (#224)

Clarify that this component uses voltage range at the chip pin, but voltage range at the board pin can be greater (e.g., for NodeMCU)

## Description:


**Related issue (if applicable):** fixes <link to issue>

**Pull request in [esphome](https://github.com/esphome/esphome) with YAML changes (if applicable):** esphome/esphome#<esphome PR number goes here>
**Pull request in [esphome-core](https://github.com/esphome/esphome-core) with C++ framework changes (if applicable):** esphome/esphome-core#<esphome-core PR number goes here>

## Checklist:

  - [ ] Branch: `next` is for changes and new documentation that will go public with the next ESPHome release. Fixes, changes and adjustments for the current release should be created against `current`.


Co-authored-by: Otto Winter <otto@otto-winter.com>
This commit is contained in:
kimonm 2019-04-15 12:45:37 -07:00 committed by Otto Winter
parent c1e42981b6
commit c9fecc93e7

View File

@ -38,8 +38,18 @@ Configuration variables:
.. note:: .. note::
On the ESP8266, the voltage range is 0 to 1.0V - so to measure any higher voltage you need to scale the voltage This component prints the voltage as seen by the chip pin. On the ESP8266, this is always 0.0V to 1.0V
down using, for example, a voltage divider circuit. Some development boards like the Wemos D1 mini include external voltage divider circuitry to scale down
a 3.3V input signal to the chip-internal 1.0V. If your board has this circuitry, add a multiply filter to
get correct values:
.. code-block:: yaml
sensor:
- platform: adc
# ...
filters:
- multiply: 3.3
.. _adc-esp32_attenuation: .. _adc-esp32_attenuation: