Lesson 15 Joystick PS2

Introduction

There are five operation directions for joystick PS2: up, down, left, right and press-down.

Components

– 1 * Raspberry Pi

– 1 * Breadboard

– 1 * Network cable (or USB wireless network adapter)

– 1 * PCF8591

– 1 * Joystick PS2 module

– 1 * 5-Pin anti-reverse cable

– Several Jumper wires (M to F)

Experimental Principle

This module has two analog outputs (corresponding to X and Y coordinates) and one digital output representing whether it is pressed on Z axis.

In this experiment, we connect pin X and Y to the analog input ports of the A/D convertor so as to convert analog quantities into digital ones. Then program on Raspberry Pi to detect the moving direction of the Joystick.

The schematic diagram:

Experimental Procedures

Step 1: Build the circuit

Raspberry Pi	PCF8591 Module	Joystick PS2
SDA	SDA
SCL	SCL
3.3V	VCC	VCC
GND	GND	GND
*	AIN0	Y
*	AIN1	X
*	AIN2	Bt

For C language users:

Step 2: Change directory

 cd /home/pi/SunFounder_SensorKit_for_RPi2/C/15_joystick_PS2/

Step 3: Compile

gcc joystick_PS2.c –lwiringPi

Step 4: Run

sudo ./a.out

For Python users:

Step 2: Change directory

 cd /home/pi/SunFounder_SensorKit_for_RPi2/Python/

Step 3: Run

sudo python 15_joystick_PS2.py

Now push the rocker upwards, and a string “up” will be printed on the screen; push it downwards, and “down” will be printed; if you push it left, “Left” will be printed on; If you push it right, and “Right” will be printed; If you press down the cap, “Button Pressed” will be printed on the screen.

C Code

#include <stdio.h>
#include <wiringPi.h>
#include <pcf8591.h>

#define PCF       120
#define uchar	unsigned char

int AIN0 = PCF + 0;
int AIN1 = PCF + 1;
int AIN2 = PCF + 2;

char *state[6] = {"home", "up", "down", "left", "right", "pressed"};

int direction(){
	int x, y, b;
	int tmp;
	x = analogRead(AIN1);
	y = analogRead(AIN0);
	b = analogRead(AIN2);
	if (y == 0)
		tmp = 1;		// up
	if (y == 255)
		tmp = 2;		// down
	
	if (x == 255)
		tmp = 3;		// left
	if (x == 0)
		tmp = 4;		// right

	if (b == 0)
		tmp = 5;		// button preesd
	if (x-125<15 && x-125>-15 && y-125<15 && y-125>-15 && b == 255)
		tmp = 0;		// home position
	
	return tmp;
}

int main (void)
{
	int tmp;
	int status = 0;
	wiringPiSetup ();
	// Setup pcf8591 on base pin 120, and address 0x48
	pcf8591Setup (PCF, 0x48);
	while(1) // loop forever
	{
		tmp = direction();
		if (tmp != status)
		{
			printf("%s\n", state[tmp]);
			status = tmp;
		}
	}
	return 0 ;
}

Python Code

#!/usr/bin/env python
#------------------------------------------------------
#
#		This is a program for JoystickPS2 Module.
#
#		This program depend on PCF8591 ADC chip. Follow 
#	the instruction book to connect the module and 
#	ADC0832 to your Raspberry Pi.
#
#------------------------------------------------------
import PCF8591 as ADC 
import time

def setup():
	ADC.setup(0x48)					# Setup PCF8591
	global state

def direction():	#get joystick result
	state = ['home', 'up', 'down', 'left', 'right', 'pressed']
	i = 0

	if ADC.read(0) <= 5:
		i = 1		#up
	if ADC.read(0) >= 250:
		i = 2		#down

	if ADC.read(1) >= 250:
		i = 3		#left
	if ADC.read(1) <= 5:
		i = 4		#right

	if ADC.read(2) == 0:
		i = 5		# Button pressed

	if ADC.read(0) - 125 < 15 and ADC.read(0) - 125 > -15	and ADC.read(1) - 125 < 15 and ADC.read(1) - 125 > -15 and ADC.read(2) == 255:
		i = 0
	
	return state[i]

def loop():
	status = ''
	while True:
		tmp = direction()
		if tmp != None and tmp != status:
			print tmp
			status = tmp

def destroy():
	pass

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