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.. _pyb.ADC:
class ADC -- analog to digital conversion: read analog values on a pin
======================================================================
.. 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
.. only:: port_wipy
Usage::
import pyb
adc = pyb.ADC(pin) # create an analog object on one of the 4 ADC channels
val = adc.read() # read an analog value
adc.deinit() # disable the adc channel
adc.init() # enable the adc channel
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.
.. only:: port_wipy
.. class:: pyb.ADC(pin)
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.read()
Read the value on the analog pin and return it. The returned value
will be between 0 and 4095.
.. only:: port_pyboard
.. 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.
.. only:: port_wipy
.. method:: adc.init()
Enable the ADC channel.
.. method:: adc.deinit()
Disable the ADC channel.
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