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.. _py_room_temp:

7.2 Room Temperature Meter
======================================

Using a thermistor and an I2C LCD1602, we can create a room temperature meter.

This project is very simple, it is based on :ref:`py_temp` with I2C LCD1602 to display the temperature.


**Schematic**

|sch_room_temp|


**Wiring**

|wiring_room_temp|

**Code**

.. note::

    * Open the ``7.2_room_temperature_meter.py`` file under the path of ``euler-kit/micropython`` or copy this code into Thonny, then click "Run Current Script" or simply press F5 to run it.

    * Don't forget to click on the "MicroPython (Raspberry Pi Pico)" interpreter in the bottom right corner. 

    * For detailed tutorials, please refer to :ref:`open_run_code_py`.


.. code-block:: python

    from lcd1602 import LCD
    import machine
    import utime
    import math

    thermistor = machine.ADC(28)
    lcd = LCD()

    while True:
        temperature_value = thermistor.read_u16()
        Vr = 3.3 * float(temperature_value) / 65535
        Rt = 10000 * Vr / (3.3 - Vr)
        temp = 1/(((math.log(Rt / 10000)) / 3950) + (1 / (273.15+25)))
        Cel = temp - 273.15
        #Fah = Cel * 1.8 + 32
        #print ('Celsius: %.2f C  Fahrenheit: %.2f F' % (Cel, Fah))
        #utime.sleep_ms(200)

        string = " Temperature is \n    " + str('{:.2f}'.format(Cel))+ " C"
        lcd.message(string)
        utime.sleep(1)
        lcd.clear()

The LCD will display the temperature value in the current environment after the program runs.

.. note:: 
    If the code and wiring are fine, but the LCD still does not display content, you can turn the potentiometer on the back to increase the contrast.