2.1.9 Joystick

Introduction

In this project, We’re going to learn how joystick works. We manipulate the Joystick and display the results on the screen.

Schematic Diagram

When the data of joystick is read, there are some differents between axis: data of X and Y axis is analog, which need to use ADC0834 to convert the analog value to digital value. Data of Z axis is digital, so you can directly use the GPIO to read, or you can also use ADC to read.

../_images/image319.png ../_images/image320.png

Experimental Procedures

Step 1: Build the circuit.

../_images/image193.png

Step 2: Go to the folder of the code.

cd /home/pi/raphael-kit/python/

Step 3: Run.

sudo python3 2.1.9_Joystick.py

After the code runs, turn the Joystick, then the corresponding values of x, y, Btn are displayed on screen.

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. After modifying the code, you can run it directly to see the effect.

#!/usr/bin/env python3

import RPi.GPIO as GPIO
import ADC0834
import time

BtnPin = 22

def setup():
    # Set the GPIO modes to BCM Numbering
    GPIO.setmode(GPIO.BCM)
    GPIO.setup(BtnPin, GPIO.IN, pull_up_down=GPIO.PUD_UP)
    ADC0834.setup()

def destroy():
    # Release resource
    GPIO.cleanup()

def loop():
    while True:
        x_val = ADC0834.getResult(0)
        y_val = ADC0834.getResult(1)
        Btn_val = GPIO.input(BtnPin)
        print ('X: %d  Y: %d  Btn: %d' % (x_val, y_val, Btn_val))
        time.sleep(0.2)

if __name__ == '__main__':
    setup()
    try:
        loop()
    except KeyboardInterrupt: # When 'Ctrl+C' is pressed, the program destroy() will be executed.
        destroy()

Code Explanation

def loop():
    while True:
        x_val = ADC0834.getResult(0)
        y_val = ADC0834.getResult(1)
        Btn_val = GPIO.input(BtnPin)
        print ('X: %d  Y: %d  Btn: %d' % (x_val, y_val, Btn_val))
        time.sleep(0.2)

VRX and VRY of Joystick are connected to CH0, CH1 of ADC0834 respectively. So the function getResult() is called to read the values of CH0 and CH1. Then the read values should be stored in the variables x_val and y_val. In addition, read the value of SW of joystick and store it into the variable Btn_val. Finally, the values of x_val, y_val and Btn_val shall be printed with print() function.

Phenomenon Picture

../_images/image194.jpeg