TouchPad Drawing Board Using ATMega32

Our electronic drawing board integrates an easy human interface with a standard electronic display; specifically the a touchpad and an oscilloscope or TV screen.
TouchPad Drawing Board
The rationale behind the drawing board is to be able to create a free hand sketch using the touchpad and have a real time display on a screen which can later be sent to the computer once finalized.This idea came about after making countless reports that required drawings that take hours to perfect on a computer when in fact with a pencil it would only be a matter of minutes. In the market, tablets are gaining popularity but they are so expensive! Hence, we thought itd be nice if we could simulate something similar under our $25 budget constraint.Thus we settled for using a touchpad to draw to an oscilloscope (and which EE doesnt have an oscilloscope handy at home!).   Better yet drawing to the TV!

High Level Design

The Rational
The original idea was to draw to a 5 TV screen using a pen input touchpad.  We had originally ordered a Jam Studio tablet but unfortunately it was too complex and poorly documented.  We couldn’t retrieve any signals from the pad.  Thus, we decided to use a regular touchpad.  This makes our design robust due to the inaccuracy of using a finger touch as opposed to a pen point.  However, the concept remains the same: to draw to a screen.
High Level Design Layout
The microcontroller acts as a translator between the touchpad and the oscilloscope.  Its job is to communicate with the touchpad using any of the 4 standard protocols: serial, ADB, PS/2, or USB and to send appropriate signals to represent the coordinates on the oscilloscope.  Our touchpad uses the ADB protocol which is MAC compatible. Also, since the oscilloscope requires analog input signals, DACs are needed to translate the digital output from the MCU to a form that can be recognized by the oscilloscope.

For more detail: TouchPad Drawing Board

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