Sudden Movement sensor build into Macbooks

Just to add on to the comments I have made earlier that the SMS sensor of the Macbook could be turned OFF by issuing the following command to the terminal
> sudo pmset -a sms 0

I was being asked if it is possible to read the value and used it as an accelerometer. The answer is Yes.
Here is a simple application that reads the accelerometer reading from a Snow leopard based Macbook

*tested on Macbook Pro*

//

//  mainDisplay.m

//  SMS_sensor3

//

//  Created by Percy on 10/14/10.

//  Copyright 2010 Minoyo. All rights reserved.

//

#import “mainDisplay.h”

#import <Foundation/Foundation.h>

#import <IOKit/IOKitLib.h>

@implementation mainDisplay

@synthesize x_Coord;

@synthesize y_Coord;

@synthesize z_Coord;

@synthesize auto_CheckBox;

@synthesize timer;

– (id)init {

structureInputSize = sizeof(struct motion_data);

structureOutputSize = sizeof(struct motion_data);

result = IOMasterPort(MACH_PORT_NULL, &masterPort);

CFMutableDictionaryRef matchingDictionary = IOServiceMatching(“SMCMotionSensor”);

result = IOServiceGetMatchingServices(masterPort, matchingDictionary, &iterator);

if (result != KERN_SUCCESS)

{

NSLog(@”IOServiceGetMatchingServices returned error.\n”, stderr);

return 0;

}

aDevice = IOIteratorNext(iterator);

IOObjectRelease(iterator);

if(aDevice == 0)

{

NSLog(@”No motion sensor available\n”, stderr);

return 0;

}

else

{

NSLog(@”Motion sensor device id = %d\n”, aDevice);

}

result = IOServiceOpen(aDevice, mach_task_self(), 0, &dataPort);

IOObjectRelease(aDevice);

if(result != KERN_SUCCESS)

{

NSLog(@”Could not open motion sensor device\n”, stderr);

return 0;

}

else

{

NSLog(@”Sucessfully open motion sensor device\n”);

}

return self;

}

-(IBAction) update_reading: (id) sender{

//x_Coord.text = @”Hello”;

//[x_Coord setTitleWithMnemonic:@”Hello”];

result = IOConnectCallStructMethod(dataPort, 

  5,

  &inputStructure, 

  structureInputSize,

  &outputStructure, 

  &structureOutputSize);

if(result != KERN_SUCCESS)

{

NSLog(@”no coords\n”);

}

else {

NSLog(@”%d %d %d\n”, outputStructure.x, outputStructure.y, outputStructure.z);

[x_Coord setTitleWithMnemonic:[NSString stringWithFormat:@”X Coord = %d”,outputStructure.x]];

[y_Coord setTitleWithMnemonic:[NSString stringWithFormat:@”Y Coord = %d”,outputStructure.y]];

    [z_Coord setTitleWithMnemonic:[NSString stringWithFormat:@”Z Coord = %d”,outputStructure.z]];

}

}

-(IBAction) checkbox_clicked: (id) sender{

if ([auto_CheckBox state] == NSOnState){

timer = [NSTimer scheduledTimerWithTimeInterval: 0.5

target: self

  selector: @selector(handleTimer🙂

  userInfo: nil

repeats: YES];

}

else

[timer invalidate];

}

– (void) handleTimer: (NSTimer *) timer{

[self update_reading:NULL];

}

@end

SMS Sensor