circuitpython/docs/library/pyb.ADC.rst

.. _pyb.ADC:

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

.. only:: port_pyboard

    Usage::

        import pyb
    
        adc = pyb.ADC(pin)              # create an analog object from a pin
        val = adc.read()                # read an analog value
    
        adc = pyb.ADCAll(resolution)    # creale an ADCAll object
        val = adc.read_channel(channel) # read the given channel
        val = adc.read_core_temp()      # read MCU temperature
        val = adc.read_core_vbat()      # read MCU VBAT
        val = adc.read_core_vref()      # read MCU VREF

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


.. only:: port_pyboard

    .. class:: pyb.ADC(pin)

       Create an ADC object associated with the given pin.
       This allows you to then read analog values on that pin.

Methods
-------

.. only:: port_pyboard

    .. method:: adc.read()

       Read the value on the analog pin and return it.  The returned value
       will be between 0 and 4095.

    .. method:: adc.read_timed(buf, timer)
    
       Read analog values into ``buf`` at a rate set by the ``timer`` object.

       ``buf`` can be bytearray or array.array for example.  The ADC values have
       12-bit resolution and are stored directly into ``buf`` if its element size is
       16 bits or greater.  If ``buf`` has only 8-bit elements (eg a bytearray) then
       the sample resolution will be reduced to 8 bits.

       ``timer`` should be a Timer object, and a sample is read each time the timer
       triggers.  The timer must already be initialised and running at the desired
       sampling frequency.

       To support previous behaviour of this function, ``timer`` can also be an
       integer which specifies the frequency (in Hz) to sample at.  In this case
       Timer(6) will be automatically configured to run at the given frequency.

       Example using a Timer object (preferred way)::

           adc = pyb.ADC(pyb.Pin.board.X19)    # create an ADC on pin X19
           tim = pyb.Timer(6, freq=10)         # create a timer running at 10Hz
           buf = bytearray(100)                # creat a buffer to store the samples
           adc.read_timed(buf, tim)            # sample 100 values, taking 10s

       Example using an integer for the frequency::

           adc = pyb.ADC(pyb.Pin.board.X19)    # create an ADC on pin X19
           buf = bytearray(100)                # create a buffer of 100 bytes
           adc.read_timed(buf, 10)             # read analog values into buf at 10Hz
                                               #   this will take 10 seconds to finish
           for val in buf:                     # loop over all values
               print(val)                      # print the value out

       This function does not allocate any memory.