File content as of revision 2:98a51d3c2e44:

/* Joystick
 
Example code of how to read a joystick
 
https://www.sparkfun.com/products/9032
 
Craig A. Evans
7 March 2015
*/
 
#include "mbed.h"
#include "N5110.h"

// change this to alter tolerance of joystick direction
#define DIRECTION_TOLERANCE 0.05
 
// connections for joystick
DigitalIn button(p15);
AnalogIn xPot(p16);
AnalogIn yPot(p17);

// LCD connections
//vcc, sce, rst, dc, mosi, clk, led
N5110 lcd(p7,p8,p9,p10,p11,p13,p26); 

// LCD dimentions
int nx= 84; //screen is 84 pixels across
int ny= 48; // by 48 pixels downwards
int i; 
int j;

// Output to screen LED's (backlights)
PwmOut PWM(p26); 

// timer to regularly read the joystick
Ticker pollJoystick;
// Serial for debug
Serial serial(USBTX,USBRX);
 
// create enumerated type (0,1,2,3 etc. for direction)
// could be extended for diagonals etc.
enum DirectionName {
    UP,
    DOWN,
    LEFT,
    RIGHT,
    CENTRE,
    UNKNOWN
};
 
// struct for Joystick
typedef struct JoyStick Joystick;
struct JoyStick {
    float x;    // current x value
    float x0;   // 'centred' x value
    float y;    // current y value
    float y0;   // 'centred' y value
    int button; // button state (assume pull-down used, so 1 = pressed, 0 = unpressed)
    DirectionName direction;  // current direction
};
// create struct variable
Joystick joystick;
 
int printFlag = 0;
 
// function prototypes
void calibrateJoystick();
void updateJoystick();
 
int main()
{
    lcd.init();
    
    while(1) {
    lcd.setXYAddress(0,0);
    for (int i=0; i<nx; i++) { 
        for (int j=0; j<ny; j++) {
            lcd.getPixel(i,j);
        }
    }
    lcd.setPixel(41,43);
    lcd.setPixel(42,43);
    lcd.setPixel(40,42);
    lcd.setPixel(41,42);
    lcd.setPixel(42,42);
    lcd.setPixel(43,42);
    lcd.setPixel(39,41);
    lcd.setPixel(40,41);
    lcd.setPixel(41,41);
    lcd.setPixel(42,41);
    lcd.setPixel(43,41);
    lcd.setPixel(44,41);
    lcd.setPixel(39,40);
    lcd.setPixel(40,40);
    lcd.setPixel(41,40);
    lcd.setPixel(42,40);
    lcd.setPixel(43,40);
    lcd.setPixel(44,40);
    lcd.setPixel(40,39);
    lcd.setPixel(41,39);
    lcd.setPixel(42,39);
    lcd.setPixel(43,39);
    lcd.setPixel(41,38);
    lcd.setPixel(42,38);
    lcd.refresh();
    }
    
    calibrateJoystick();  // get centred values of joystick
    pollJoystick.attach(&updateJoystick,1.0/10.0);  // read joystick 10 times per second
 
    while(1) {
 
        if (printFlag) {  // if flag set, clear flag and print joystick values to serial port
            printFlag = 0;
            serial.printf("x = %f y = %f button = %d ",joystick.x,joystick.y,joystick.button);
 
            // check joystick direction
            if (joystick.direction == UP)
                serial.printf(" UP\n");
            if (joystick.direction == DOWN)
                serial.printf(" DOWN\n");
            if (joystick.direction == LEFT)
                serial.printf(" LEFT\n");
            if (joystick.direction == RIGHT)
                serial.printf(" RIGHT\n");
            if (joystick.direction == CENTRE)
                serial.printf(" CENTRE\n");
            if (joystick.direction == UNKNOWN)
                serial.printf(" Unsupported direction\n");
 
        }
 
    }
}
 
// read default positions of the joystick to calibrate later readings
void calibrateJoystick()
{
    button.mode(PullDown);
    // must not move during calibration
    joystick.x0 = xPot;  // initial positions in the range 0.0 to 1.0 (0.5 if centred exactly)
    joystick.y0 = yPot;
}
void updateJoystick()
{
    // read current joystick values relative to calibrated values (in range -0.5 to 0.5, 0.0 is centred)
    joystick.x = xPot - joystick.x0;
    joystick.y = yPot - joystick.y0;
    // read button state
    joystick.button = button;
 
    // calculate direction depending on x,y values
    // tolerance allows a little lee-way in case joystick not exactly in the stated direction
    if ( fabs(joystick.y) < DIRECTION_TOLERANCE && fabs(joystick.x) < DIRECTION_TOLERANCE) {
        joystick.direction = CENTRE;
    } else if ( joystick.y > DIRECTION_TOLERANCE && fabs(joystick.x) < DIRECTION_TOLERANCE) {
        joystick.direction = UP;
    } else if ( joystick.y < DIRECTION_TOLERANCE && fabs(joystick.x) < DIRECTION_TOLERANCE) {
        joystick.direction = DOWN;
    } else if ( joystick.x > DIRECTION_TOLERANCE && fabs(joystick.y) < DIRECTION_TOLERANCE) {
        joystick.direction = RIGHT;
    } else if ( joystick.x < DIRECTION_TOLERANCE && fabs(joystick.y) < DIRECTION_TOLERANCE) {
        joystick.direction = LEFT;
    } else {
        joystick.direction = UNKNOWN;
    }
 
    // set flag for printing
    printFlag = 1;
}