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.. _2.1.2_py_pi5:
2.1.2 Micro Switch
======================
Introduction
--------------------
In this project, we will learn how to use Micro Switch. A Micro Switch is a small, very sensitive switch which requires minimum compression to activate. Because they are reliable and sensitive, micro switches are often used as a safety device.
They are used to prevent doors from closing if something or someone is in the way and other applications similar.
Required Components
------------------------------
In this project, we need the following components.
.. image:: ../python_pi5/img/2.1.2_micro_switch_list.png
It's definitely convenient to buy a whole kit, here's the link:
.. list-table::
:widths: 20 20 20
:header-rows: 1
* - Name
- ITEMS IN THIS KIT
- LINK
* - Raphael Kit
- 337
- |link_Raphael_kit|
You can also buy them separately from the links below.
.. list-table::
:widths: 30 20
:header-rows: 1
* - COMPONENT INTRODUCTION
- PURCHASE LINK
* - :ref:`cpn_gpio_extension_board`
- |link_gpio_board_buy|
* - :ref:`cpn_breadboard`
- |link_breadboard_buy|
* - :ref:`cpn_wires`
- |link_wires_buy|
* - :ref:`cpn_resistor`
- |link_resistor_buy|
* - :ref:`cpn_led`
- |link_led_buy|
* - :ref:`cpn_micro_switch`
- \-
* - :ref:`cpn_capacitor`
- |link_capacitor_buy|
Schematic Diagram
-----------------
Connect the left pin of the Micro Switch to GPIO17, and two LEDs to
pin GPIO22 and GPIO27 respectively. Then when you press and release the
move arm of the Micro Switch, you can see the two LEDs light up alternately.
.. image:: ../python_pi5/img/2.1.2_micro_switch_schematic_1.png
.. image:: ../python_pi5/img/2.1.2_micro_switch_schematic_2.png
Experimental Procedures
-----------------------
**Step 1:** Build the circuit.
.. image:: ../python_pi5/img/2.1.2_micro_switch_circuit.png
**Step 2**: Get into the folder of the code.
.. raw:: html
.. code-block::
cd ~/raphael-kit/python-pi5
**Step 3**: Run.
.. raw:: html
.. code-block::
sudo python3 2.1.2_MicroSwitch_zero.py
While the code is running, press the moving arm, then the yellow LED lights up; release the moving arm, the red LED turns on.
.. warning::
If there is an error prompt ``RuntimeError: Cannot determine SOC peripheral base address``, please refer to :ref:`faq_soc`
**Code**
.. note::
You can **Modify/Reset/Copy/Run/Stop** the code below. But before that, you need to go to source code path like ``raphael-kit/python-pi5``. After modifying the code, you can run it directly to see the effect.
.. raw:: html
.. code-block:: python
#!/usr/bin/env python3
from gpiozero import LED, Button # Import LED and Button classes from gpiozero
from time import sleep # Import sleep function for delays
# Initialize micro switch on GPIO pin 17 with the pull-up resistor disabled
micro_switch = Button(17, pull_up=False)
# Initialize LED1 connected to GPIO pin 22
led1 = LED(22)
# Initialize LED2 connected to GPIO pin 27
led2 = LED(27)
try:
# Continuously check the state of the micro switch and control LEDs accordingly
while True:
if micro_switch.is_pressed: # If the micro switch is pressed
print('LED1 ON') # Print a message to the console
led1.on() # Turn on LED1
led2.off() # Turn off LED2
else: # If the micro switch is not pressed
print(' LED2 ON') # Print a message to the console
led1.off() # Turn off LED1
led2.on() # Turn on LED2
sleep(0.5) # Pause for 0.5 seconds before checking the switch again
except KeyboardInterrupt:
# Handle KeyboardInterrupt (Ctrl+C) to exit the loop gracefully
pass
**Code Explanation**
#. This line sets the script to run with Python 3. It imports ``LED`` and ``Button`` from ``gpiozero`` for controlling GPIO devices, and ``sleep`` from ``time`` for delays.
.. code-block:: python
#!/usr/bin/env python3
from gpiozero import LED, Button # Import LED and Button classes from gpiozero
from time import sleep # Import sleep function for delays
#. Initializes a micro switch connected to GPIO pin 17 with the pull-up resistor disabled, and two LEDs connected to GPIO pins 22 and 27.
.. code-block:: python
# Initialize micro switch on GPIO pin 17 with the pull-up resistor disabled
micro_switch = Button(17, pull_up=False)
# Initialize LED1 connected to GPIO pin 22
led1 = LED(22)
# Initialize LED2 connected to GPIO pin 27
led2 = LED(27)
#. In the main loop, it checks the state of the micro switch. If pressed, LED1 turns on and LED2 off. If not pressed, LED1 turns off and LED2 on. The loop repeats every 0.5 seconds. Catches a KeyboardInterrupt (like Ctrl+C) to allow for graceful script termination.
.. code-block:: python
try:
# Continuously check the state of the micro switch and control LEDs accordingly
while True:
if micro_switch.is_pressed: # If the micro switch is pressed
print('LED1 ON') # Print a message to the console
led1.on() # Turn on LED1
led2.off() # Turn off LED2
else: # If the micro switch is not pressed
print(' LED2 ON') # Print a message to the console
led1.off() # Turn off LED1
led2.on() # Turn on LED2
sleep(0.5) # Pause for 0.5 seconds before checking the switch again
except KeyboardInterrupt:
# Handle KeyboardInterrupt (Ctrl+C) to exit the loop gracefully
pass