1. Obtain laser pointer coordinates

2. Send laser pointer coordinates to the laptop through the standard PS/2 mouse port

3. Pixel Mapping

4. Attach a button to the laser pointer

4 major components to laser mouse

Obtain laser pointer coordinatesHow to track the laser point?

The brightest point in the image

Problems:

Noise so that the crosshairs can jump around and pick up static pixels which would be bad for moving the mouse due to noise

Additional techniques:

Color mapping to eliminate all other colors below 250 (0-255 scale). The laser point is color 254.

Solutions-- Better algorithms:

Track the brightest 2 pixels

Try to find a circle bright spot

Current VGA Display

Obtain laser pointer coordinates

LaserSpot – Find the brightest pixel as data is being written to memory.

CrossHairs – As data is being written to the VGA, blank out all pixels except the brightest and draw the crosshairs on the row and column with the brightest pixel.

Normal camera interface

Send coordinates to the laptop

PS/2 Port

Problems:

Not very good documentation

Relative coordinates vs. fixed coordinates

Solutions:

• Use Xbus interface

• Use standard PS/2 protocol

PS/2 Protocol

• Send information to PS/2 port using standard protocol– Use relative coordinates coordinates

<Show timing diagram> •Each transmission includes 11 bits

•Must send 3 consecutive data packets to move mouse once

Pixel mapping

Projection screen

Laptop screen

Pixel Mapping

• The problem– Moving the laser pointer 1 foot on the

projection screen means moving the mouse x pixels on the laptop screen. What is x?

• The solutions– Perform a calibration program before starting to

use the laser pointer as the mouse. Similar to Palm calibration program.

Attach a button

How to connect the button to the XSBoard?

•Wire

•Radio Frequency

•Ultrasonic Transmission

•Camera interface

Conclusion

1. Laser spot tracking - done

2. PS/2 mouse port – this week (week 6)

3. Pixel mapping – weeks 7 & 8

4. Laser button – week 9

Any Questions?