gistfile1.c

/////////////////////////////////////////////////////////////////////////
// RICHARD BAMFORD - 2015 - University Of Hull - Embedded Systems Club //
/////////////////////////////////////////////////////////////////////////

#include <LiquidCrystal.h>
// Accelerometer pins
#define XPIN 1
#define YPIN 2
// This is the average number which the accelerometer rests at.
#define NORM 344


// Init the LCD screen library with the connected pins.
LiquidCrystal lcd(7, 8, 9, 10, 11, 12);

// Represent where in the LCD's memory the data for our images are held.
byte BlockDataLocation  = (byte)0;
byte PlayerDataLocation = (byte)1;



// Global struct to hold data for all things we want to draw (Blocks and Player);
struct Entity {
  double x;
  double y;
};

// Array to hold all the entities currently on the screen.
// 32 is the number of cells we can acces on the screen.
Entity Entities[32];



// This will alow us to 'smooth' the readings from the accelerometer.
struct Smoother {
  int Readings[10];
  int Total = 0;
  int Average = 0;
};

// Which index in the smoothers we are reading from.
int index;

Smoother x;
Smoother y;

// we need the previous to calculate the DT of movement.
int PreviousXMovement;
int PreviousYMovement;

int XTilt;
int YTilt;

void UpdateAccelerometerValues()
{
  x.Total = x.Total - x.Readings[index];
  x.Readings[index] = analogRead(XPIN);
  x.Total = x.Total + x.Readings[index];
  
  y.Total = y.Total - y.Readings[index];
  y.Readings[index] = analogRead(YPIN);
  y.Total = y.Total + y.Readings[index];

  index = index + 1;
  if (index == 10) index = 0;
  
  x.Average = x.Total / 10;
  y.Average = y.Total / 10;
  
  int XMovement = x.Average - NORM;
  int YMovement = NORM - y.Average;
  
  // DT
  XTilt = PreviousXMovement - XMovement;
  YTilt = PreviousYMovement - YMovement;
  
  PreviousXMovement = XMovement;
  PreviousYMovement = YMovement;
}

void setup()
{
  Serial.begin(9600);
  
  // The actual data where we want to send to the LCD.
  // Not declaring these global to save some scrappy memory.
  byte blockData[8] = {
    B11111,
    B11111,
    B11111,
    B11111,
    B11111,
    B11111,
    B11111,
    B11111
  };
  
  byte playerData[8] = {
    B01110,
    B10001,
    B10101,
    B11001,
    B11001,
    B10101,
    B10001,
    B01110,
  };

  // Attach the data specified above to the locations (1st arg)
  lcd.createChar(BlockDataLocation, blockData);
  lcd.createChar(PlayerDataLocation, playerData);
  
  lcd.begin(16, 2);
  
  // Add our player to the entities list, always the first index.
  Entity player = { 0, 0 };
  Entities[0] = player;
  
  for (int i = 0; i < 10; i++)
  {
    x.Readings[i] = NORM;
    y.Readings[i] = NORM;
  }
}


void loop()
{
  // Clear the sceen and set cursor to upper-left.
  lcd.clear();
  
  UpdateAccelerometerValues();
  
  // Move the player according to the new accelerometer values capped.
  Entity ply = Entities[0];
  ply.x += XTilt;
  ply.y += YTilt;
  
  Serial.print("X: "); Serial.print(ply.x);
  Serial.print("Y: "); Serial.print(ply.y);
  Serial.print("\n");
  
  ply.x = map(ply.x, 0, 1, 0, 1);
  ply.y = map(ply.x, 0, 16, 0, 16);
 
  
  // total size of array / the size of a single entity gives us the number of elements we have in it.
  for (int i = 0; i < sizeof(Entities)/sizeof(Entity); i++)
  {
    Entity currentEnt = Entities[i];
    lcd.setCursor(currentEnt.x, currentEnt.y);
    
    // If it's the first element (always player)
    if (i == 0)
    {
      lcd.write(PlayerDataLocation);
    }
    else
    {
      lcd.write(BlockDataLocation);
    }
  }
  
  lcd.setCursor(0, 0);
  lcd.write(PlayerDataLocation);
  
  // 1 Frame every 350ms
  delay(500);
}