.. currentmodule:: machine

class ADC -- analog to digital conversion
=========================================

Usage::

   import machine

   adc = machine.ADC()             # create an ADC object
   apin = adc.channel(pin='GP3')   # create an analog pin on GP3
   val = apin()                    # read an analog value

Constructors
------------

.. class:: ADC(id=0, \*, bits=12)

   Create an ADC object associated with the given pin.
   This allows you to then read analog values on that pin.
   For more info check the `pinout and alternate functions
   table. <https://raw.githubusercontent.com/wipy/wipy/master/docs/PinOUT.png>`_ 

   .. warning:: 

      ADC pin input range is 0-1.4V (being 1.8V the absolute maximum that it 
      can withstand). When GP2, GP3, GP4 or GP5 are remapped to the 
      ADC block, 1.8 V is the maximum. If these pins are used in digital mode, 
      then the maximum allowed input is 3.6V.

Methods
-------

.. method:: ADC.channel(id, \*, pin)

   Create an analog pin. If only channel ID is given, the correct pin will
   be selected. Alternatively, only the pin can be passed and the correct
   channel will be selected. Examples::

      # all of these are equivalent and enable ADC channel 1 on GP3
      apin = adc.channel(1)
      apin = adc.channel(pin='GP3')
      apin = adc.channel(id=1, pin='GP3')

.. method:: ADC.init()

   Enable the ADC block.

.. method:: ADC.deinit()

   Disable the ADC block.

class ADCChannel --- read analog values from internal or external sources
=========================================================================

ADC channels can be connected to internal points of the MCU or to GPIO pins.
ADC channels are created using the ADC.channel method.

.. method:: adcchannel()

   Fast method to read the channel value.

.. method:: adcchannel.value()

   Read the channel value.

.. method:: adcchannel.init()

   Re-init (and effectively enable) the ADC channel.

.. method:: adcchannel.deinit()

   Disable the ADC channel.
