:mod:`ds18b20` --- communicate with DS18B20 via UART/1-Wire
===========================================================

.. module:: ds18b20
   :synopsis: communicate with DS18B20 temperature sensor via UART/1-Wire

This module provides control fo the Maxim DS18B20 temperature sensor provided it uses 3-wire scheme (with separate VCC pin)

class DS18B20
-------------

The DS18B20 class provides an interace to the Maxim temperature sensor. Create an instance of this class to measure and read the temperature and control the sensor resolution. Connection: Pin1 (GND) to ground, Pin2 (DQ) to the UART_TX pin, Pin3 (Vdd) to 3.3/5V

Usage example::

    import ds18b20
    import pyb

    ds = ds18b20.DS18B20(pyb.UART(1))
    ds.measure()
    pyb.delay(1000)
    ds.temperature()

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

.. class:: DS18B20(uart)

   Construct an DS18B20 object. The only parameter is the UART instance (ds18b20 DQ pin *must* be connected to UART TX pin)

Instance members
----------------

The following instance members are publicly accessible.

.. data:: DS18B20.resolution

   The resolution (9-12bits) of the connected sensor. The value is valid only after a successfull ``temperature()`` read.

Setup commands
--------------

.. method:: DS18B20.reset()

   Reset the device. Normally you do not need to call this function manually - all other member functions call it anyway.
   Return value: ``True`` if the device responded with a presence pulse, ``False`` othrewise

.. method:: DS18B20.set_resulution(value)

   Set the resolution. ``value`` must be in the range of [9-12]. Fallback is 9.
   Return value: boolean (operation success)

Measurement
-----------

.. method:: DS18B20.measure()

   Request a temperature measurement. See `the datasheet <https://datasheets.maximintegrated.com/en/ds/DS18B20.pdf>`_ (484KiB PDF) for how long a single measurement takes. The function return immediately, i.e. to read the temperature user has to call, for example, ``pyb.delay(value)``.
   Return value: boolean (operation success)

.. method:: DS18B20.temperature()

   Read and return the last measured temperature.
   Return value: temperature (float) or ``None``.