2.1.3 Tilt Switch

Introduction

This is a ball tilt-switch with a metal ball inside. It is used to detect inclinations of a small angle.

Required Components

In this project, we need the following components.

Schematic Diagram

Experimental Procedures

Step 1: Build the circuit.

Step 2: Change directory.

cd ~/davinci-kit-for-raspberry-pi/python-pi5

Step 3: Run.

sudo python3 2.1.3_Tilt_zero.py

Place the tilt vertically, and the green LED will turns on. If you tilt it, “Tilt!” will be printed on the screen and the red LED will turns on. Place it vertically again, and the green LED will lights on.

Code

Note

You can Modify/Reset/Copy/Run/Stop the code below. But before that, you need to go to source code path like davinci-kit-for-raspberry-pi/python-pi5. After modifying the code, you can run it directly to see the effect.

#!/usr/bin/env python3
from gpiozero import LED, Button

# Initialize the Button for the tilt sensor and LEDs using GPIO Zero
TiltPin = Button(17, pull_up=False)  # Tilt sensor connected to GPIO pin 17, pull-up resistor disabled
green_led = LED(27)  # Green LED connected to GPIO pin 27
red_led = LED(22)   # Red LED connected to GPIO pin 22

def detect():
    """
    Detect the tilt sensor state and control the LEDs.
    Turns on the red LED and turns off the green LED when tilted.
    Turns off the red LED and turns on the green LED when not tilted.
    """
    if TiltPin.is_pressed:  # Check if the sensor is tilted
        print('    *************')
        print('    *   Tilt!   *')
        print('    *************')
        red_led.on()   # Turn on red LED
        green_led.off()  # Turn off green LED
    else:  # If the sensor is not tilted
        red_led.off()  # Turn off red LED
        green_led.on()  # Turn on green LED

try:
    while True:
        # Continuously check the tilt sensor state and update LEDs
        TiltPin.when_pressed = detect
        TiltPin.when_released = detect

except KeyboardInterrupt:
    # Handle KeyboardInterrupt (Ctrl+C) to exit the loop gracefully
    pass

Code Explanation

1. This line sets the script to run with Python 3 and imports LED and Button from gpiozero for controlling GPIO devices.

   #!/usr/bin/env python3
   from gpiozero import LED, Button
   

2. Initializes the tilt sensor connected to GPIO pin 17 (with pull-up resistor disabled) and two LEDs connected to GPIO pins 27 and 22.

   # Initialize the Button for the tilt sensor and LEDs using GPIO Zero
   TiltPin = Button(17, pull_up=False)  # Tilt sensor connected to GPIO pin 17, pull-up resistor disabled
   green_led = LED(27)  # Green LED connected to GPIO pin 27
   red_led = LED(22)   # Red LED connected to GPIO pin 22
   

3. Defines the detect function, which checks the state of the tilt sensor. If tilted, it turns on the red LED and off the green LED. If not tilted, it does the opposite.

   def detect():
       """
       Detect the tilt sensor state and control the LEDs.
       Turns on the red LED and turns off the green LED when tilted.
       Turns off the red LED and turns on the green LED when not tilted.
       """
       if TiltPin.is_pressed:  # Check if the sensor is tilted
           print('    *************')
           print('    *   Tilt!   *')
           print('    *************')
           red_led.on()   # Turn on red LED
           green_led.off()  # Turn off green LED
       else:  # If the sensor is not tilted
           red_led.off()  # Turn off red LED
           green_led.on()  # Turn on green LED
   

4. The main loop assigns the detect function to both when_pressed and when_released events of the tilt sensor. The try-except block handles a KeyboardInterrupt for graceful termination.

   try:
       while True:
           # Continuously check the tilt sensor state and update LEDs
           TiltPin.when_pressed = detect
           TiltPin.when_released = detect
   
   except KeyboardInterrupt:
       # Handle KeyboardInterrupt (Ctrl+C) to exit the loop gracefully
       pass