Yes, this is more or less your average touchpad that one can find from inside a laptop. This model, like majority of touchpads out there operates with PS/2 standard. This means that it can be directly plugged in to a PS/2 connector and with proper drivers, function as a mouse.

As it happens the PS/2 communication is not that difficult to achieve with an Arduino board. Kristopher has written an Arduino/Wiring library that offers all the functionality that we need at this point.

I will be using the MAX7219 Led Controller too and for this one can use LedControl library , written by Eberhard Fahle.

Step 1: Putting the Touchpad Together

I happened to find this TouchPad from inside a dead Fujitsu Siemens laptop. Model number for the pad is ALPS JCI-S1S. These kind of modules are easy to source also from ebay etc.

Ground and supply voltage pins are usually easy to guess just by looking at the circuit board but the data and clock pins were found by just pure trial and error method.

As the flexible cable is not the best suited for use with Arduino, I soldered better wires for the pins. Hot glue was used to make the connection more secure.

Step 2: Coding - Part I

Here are both the TouchPad and the 8x8 Ledmatrix hooked up to Arduino. Touchpad uses the 5 and 6 pins on Arduino and the MAX7219 utilizes the pins 10, 11 and 12. What goes were can be easy seen inside the code.

First test - Direction and buttons

TouchPad reports the movement of the finger. One gets a pair of coordinates that indicated the amount of movement and the direction from the last position. For example -12, 2 would mean a swipe towards 10 o'clock and the X-axis movement being faster.

As it turns out, even the tap functionality works perfectly.

----------------------

The code:

// Arduino + Laptop TouchPad. Basic functionality
//
// http://Metku.net
// Jani Pönkkö
// 23.07.2009

#include "PS2Mouse.h"
#include "LedControl.h"

#define MDATA 5 // touchpad ps/2 data pin
#define MCLK 6 // touchpad ps/2 clock pin
#define SENSITIVITY 5 // amount of movement needed to get a reaction

LedControl lc=LedControl(12,11,10,1); // forum pin outs

PS2Mouse mouse_one(MCLK, MDATA, REMOTE);

void setup()
{
lc.setIntensity(0,8);
lc.shutdown(0,false); // need to take MAX out of shutdown
lc.clearDisplay(0);
delay(10);

Serial.begin(115200);
mouse_one.initialize();
mouse_one.set_scaling_1_1();
}

void loop()
{
int data[2];
mouse_one.report(data);
Serial.print(data[0]); // Status Byte
Serial.print(":");
Serial.print(data[1]); // X Movement Data
Serial.print(",");
Serial.print(data[2]); // Y Movement Data
Serial.println();

// draw the initial box to the center
lc.clearDisplay(0);

// if no movement, light up the center block
if(data[1]==0 && data[2]==0)
{
    lc.setLed(0,3,3,true);
    lc.setLed(0,3,4,true);
    lc.setLed(0,4,3,true);
    lc.setLed(0,4,4,true);
}

// X-movement
if(data[1]>SENSITIVITY)
{
    lc.setLed(0,1,3,true);
    lc.setLed(0,1,4,true);
    lc.setLed(0,2,3,true);
    lc.setLed(0,2,4,true);
}
if(data[1]<-SENSITIVITY)
{
    lc.setLed(0,5,3,true);
    lc.setLed(0,5,4,true);
    lc.setLed(0,6,3,true);
    lc.setLed(0,6,4,true);
}

// Y-movement
if(data[2]>SENSITIVITY)
{
    lc.setLed(0,3,1,true);
    lc.setLed(0,3,2,true);
    lc.setLed(0,4,1,true);
    lc.setLed(0,4,2,true);
}
   if(data[2]<-SENSITIVITY)
{
    lc.setLed(0,3,5,true);
    lc.setLed(0,3,6,true);
    lc.setLed(0,4,5,true);
    lc.setLed(0,4,6,true);
}

// Left button
if(data[0]==10)
{
    lc.setLed(0,0,6,true);
    lc.setLed(0,0,7,true);
    lc.setLed(0,1,6,true);
    lc.setLed(0,1,7,true);
}

   // Middle button
if(data[0]==12)
{
    lc.setLed(0,3,6,true);
    lc.setLed(0,3,7,true);
    lc.setLed(0,4,6,true);
    lc.setLed(0,4,7,true);
}

// Right button
if(data[0]==9)
{
    lc.setLed(0,6,6,true);
    lc.setLed(0,6,7,true);
    lc.setLed(0,7,6,true);
    lc.setLed(0,7,7,true);
}

// some delay so one can see the leds properly
delay(100);

}

Step 3: Coding - Part II

Second test - iPod style gesture

I adapted the code a bit so it could react to a iPod style circular gesture. This could be use to speed up a motor, increase volume, turn a servo etc... hmm... a game of safe cracker perhaps... ;)

The code may not be the highest quality but it should give you the idea what is happening.

----------------------------
The code:

// Arduino + Laptop TouchPad. iPod style gesture
//
// http://Metku.net
// Jani Pönkkö
// 23.07.2009

#include "PS2Mouse.h"
#include "LedControl.h"

#define MDATA 5 // touchpad ps/2 data pin
#define MCLK 6 // touchpad ps/2 clock pin
#define SENSITIVITY 5 // amount of movement needed to get a reaction

LedControl lc=LedControl(12,11,10,1); // forum pin outs

PS2Mouse mouse_one(MCLK, MDATA, REMOTE);

int value;
int i;
int l;
int dir; // indicates where user is "turning" the dial

void setup()
{
   lc.setIntensity(0,8);
   lc.shutdown(0,false); // need to take MAX out of shutdown
   lc.clearDisplay(0);
   delay(10);

   Serial.begin(115200);
mouse_one.initialize();
   mouse_one.set_scaling_1_1();

   value=7;
}

void loop()
{
   int data[2];

   mouse_one.report(data);

   // handle the leds. Made this way to combat flickering...
   for(i=7;i>=0;i--)
   {
    if(value<=i)
    {
      for(l=0;l<=7;l++)
      lc.setLed(0,l,i,true);
    }
    else
    {
      for(l=0;l<=7;l++)
      lc.setLed(0,l,i,false);
   }
}

// Moving to the right
if(data[1]>SENSITIVITY)
{
   if(dir==0) // direction is counter clockwise
   dir=-1; // dec
}

// Moving to the left
if(data[1]<-SENSITIVITY)
{
if(dir==0) // direction is clockwise
dir=1; // incrementation
}

// top of the "turn"
if(data[2]>SENSITIVITY)
{
   dir=0; // we got the start indication (top part of the circle)
}

// bottom of the "turn"
if(data[2]<-SENSITIVITY)
{
   if(dir==-1) // we got counter clockwise turn
   {
     if(value>0)
    {
      value=value-1;
      dir=-2; // reset the value to something non-valid
    }
}
if(dir==1)
{
     if(value<7)
    {
       value=value+1;
      dir=-2; // reset the value to something non-valid
    }
}
}

// some delay so one can see the leds properl
delay(100);

}

--------------

I hope that you found this short tutorial useful. If you ever find this material useful, please, share your findings and projects with us. Either by registering here to Allthemods.com or by visiting Metku.net . Thanks.