Chapter 2 Button & LED
=========================
Usually, there are three essential parts in a complete automatic control device: 
INPUT, OUTPUT, and CONTROL. In last section, the LED module was the output part 
and ESP32-S3 was the control part. In practical applications, we not only make 
LEDs flash, but also make a device sense the surrounding environment, receive 
instructions and then take the appropriate action such as LEDs light up, make a 
buzzer turn ON and so on.

.. image:: img/other/2.png

Next, we will build a simple control system to control a LED through a push butt
on switch.

Project 2.1 Button & LED
----------------------------
In the project, we will control the LED state through a Push Button Switch. When 
the button is pressed, our LED will turn ON, and when it is released, the LED will 
turn OFF.

Component List
^^^^^^^^^^^^^^^
- ESP32-S3-WROOM x1
- GPIO Extension Board x1
- 830 Tie-Points Breadboard x1
- LED x1
- Resistor 220Ω x1
- Resistor 10kΩ x2
- Jumper Wire x4
- Button x1

Component knowledge
^^^^^^^^^^^^^^^^^^^^
:ref:`Button <cpn_button>`
"""""""""""""""""""""""""""

Connect
^^^^^^^^^^
.. image:: img/connect/2.png

Sketch
^^^^^^^
This project is designed to learn to control an LED with a push button switch. 
First, we need to read the state of the switch and then decide whether the LED 
is turned on or not based on it. Move the program folder “Basic_Starter
_Kit_for_ESP32_S3/Python/Python_Codes” to disk(D) in advance with the path of “
D:/Micropython_Codes”. Open “Thonny”，click “This computer” >> “D:” >> “Micropython
_Codes” >> “02.1_ButtonAndLed” and double click “ButtonAndLed.py”.

**02.1_ButtonAndLed**

.. image:: img/software/2.1.png

Click “Run current script” shown in the box of the above illustration, press the 
push button switch, LED turns ON; release the switch, LED turns OFF.

.. image:: img/phenomenon/2.1.png

**Upload Code to ESP32S3**
As shown in the following illustration, right-click file 02.1_ButtonAndLed and 
select “Upload to /” to upload code to ESP32S3.

.. image:: img/software/2.1-1.png

Upload boot.py in the same way.

.. image:: img/software/2.1-2.png

The following is the program code:

.. code-block:: python

    from machine import Pin

    led = Pin(2, Pin.OUT)

    #create button object from pin13,Set Pin13 to Input
    button = Pin(13, Pin.IN,Pin.PULL_UP) 

    try:
        while True:
        if not button.value():     
            led.value(1)  #Set led turn on
        else:
            led.value(0)  #Set led turn off
    except:
        pass

Project 2.2 MINI table lamp
----------------------------

We will also use a push button switch, LED and ESP32-S3 to make a MINI table lamp 
but this will function differently: Press the button, the LED will turn ON, and 
pressing the button again, the LED turns OFF. The ON switch action is no longer 
momentary (like a door bell) but remains ON without needing to continually press 
on the Button Switch. First, let us learn something about the push button switch.

Debounce for Push Button
^^^^^^^^^^^^^^^^^^^^^^^^^^

The moment when a push button switch is pressed, it will not change from one state 
to another state immediately. Due to tiny mechanical vibrations, there will be a 
short period of continuous buffeting before it completely reaches another state 
too fast for humans to detect but not for computer microcontrollers. The same is 
true when the push button switch is released. This unwanted phenomenon is known 
as “bounce”.

.. image:: img/other/2.2.png

Therefore, if we can directly detect the state of the push button switch, there 
are multiple pressing and releasing actions in one pressing cycle. This buffeting 
will mislead the high-speed operation of the microcontroller to cause many false 
decisions. Therefore, we need to eliminate the impact of buffeting. Our solution: 
to judge the state of the button multiple times. Only when the button state is 
stable (consistent) over a period of time, can it indicate that the button is 
actually in the ON state (being pressed). This project needs the same components 
and circuits as we used in the previous section.

Code
^^^^^^^
**02.2_Tablelamp**
Move the program folder “Basic_Starter_Kit_for_ESP32_S3/Python/Python_C
odes” to disk(D) in advance with the path of “D:/Micropython_Codes”. Open “Thonn
y”，click “This computer” >> “D:” >> “Micropython_Codes” >> “02.2_TableLamp”and dou
ble click “TableLamp.py”.

.. image:: img/software/2.2.png

Click “Run current script” shown in the box of the above illustration, press the 
push button switch, LED turns ON; press it again, LED turns OFF.

.. image:: img/phenomenon/2.2.png

**Upload code to ESP32S3**
As shown in the following illustration, right-click file 02.2_TableLamp and 
select “Upload to /” to upload code to ESP32S3.

.. image:: img/software/2.2-1.png

Upload boot.py in the same way.

.. image:: img/software/2.2-2.png

Press ESP32S3’s reset key, and then push the button switch, LED turns ON; Push 
the button again, LED turns OFF.

.. image:: img/phenomenon/2.2.png

The following is the program code:

.. code-block:: python

    import time
    from machine import Pin

    led = Pin(2, Pin.OUT)        
    button = Pin(13, Pin.IN,Pin.PULL_UP)

    def reverseGPIO():
        if led.value():
            led.value(0)
        else:
            led.value(1)

    while True:
    if not button.value():
        time.sleep_ms(20)
        if not button.value():
            reverseGPIO()
            while not button.value():
                time.sleep_ms(20)