1. Obtain laser pointer coordinates

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

3. Pixel Mapping between camera image and laptop screen & calibration

4. Attach a button to the laser pointer

Four major components to laser mouse

Overview of Design

• Use Camera Interface

Send Images to FPGA

• LaserSpot module

Analyze each image for

brightest spot

• Use Xbus interface

Send coordinates to Controller

• Use Windows pen drivers

Perform coordinate translation

• Use PS/2 interface

Send coordinates to

laptop

Camera taking constant images

1. Obtain laser pointer coordinates

• How to track the laser point?

• Color mapping to eliminate colors below a brightness threshold

• Upgrades to improve correctness– Multiple bright pixels in one area

Current VGA Display

1. 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

2. Send coordinates to the laptop

Controller to laptop through the PS/2 Port

Problems:

• Difficult to find documentation

• Modify driver to use absolute coordinates

Strategy:

• Use Xbus interface to Controller

• Use standard PS/2 protocol

2a. Send coordinates to Controller

Xbus Interface to connect FPGA and Controller

Use Xbus interface designed in class

2b. PS/2 Mouse Port Protocol

8 data bits, least significant bit first.

0 1

Must send 3 consecutive data packets to move mouse• Packet 1 => Mouse click info and movement info

• Packet 2 => new x position (absolute position)

• Packet 3 => new y position (absolute position)

2b. PS/2 Mouse Port Protocol

Composition of each data packet:

• Packet 1 Format: Overflow bits (2), X & Y direction (2), Right & Left mouse click (2), Fixed (2)

• Packet 2 Format: X direction movement

• Packet 3 Format: Y direction movement

Inputs & Outputs of Controller implementation in software:

• Input: FPGA coordinates, Mouse click

• Output: Data to PS/2 port, PS/2 clock (75-150sec)

• External: Pixel Mapping, eliminate laser pointer shaking (both may be able to be implemented in the driver)

3. Pixel mapping

Camera Image of Projection Screen

Laptop screen

256x256 pixels

• 640x480 pixels?

• 800x600 pixels?

• 1024x768 pixels?

Pixel mapping & calibration done in the driver

3. Pixel Mapping

• Calibration– Perform a calibration program before starting to use the laser

pointer as the mouse. Similar to Palm calibration program. The Windows driver is the Unidriver

– Pen Calibration: PENCAL.DLL

• Pixel Mapping– Moving the laser pointer 1 foot on the projection screen means

moving the mouse x pixels in the camera image which is y pixels on the laptop screen. What are x and y?

– Virtual device driver: VPENDC.VXD– Pen driver: PENC.DRV

4. Attach a button

How to connect the button to the Controller?

• Wire

• Radio Frequency

• Camera interface

Laser Pointer Kit

The mouse click will be transmitted in

Packet 1 of the PS/2 Protocol.

Conclusion

1. Laser spot tracking - functional, upgrades pending

2. PS/2 mouse port – this week (week 7), continual upgrades

3. Pixel mapping – weeks 8 & 9, continual upgrades

4. Laser button – week 9 & 10

Any Questions?