Build It: The Electronic Post-It Note

Who needs pen and paper? Jot down reminders on a digital screen, using only your finger

Digital Post-It

Luis Bruno, Eric Heintz

"Pick up milk." "Feed dog." "Finish homemade nuclear sub." Like many people, I can't function without writing little reminders to myself. But using one paper sticky note after another causes a lot of clutter and can be pretty wasteful. Instead, assemble a bunch of surplus parts into a digital note system for your kitchen or office. Just write out your message with your fingertip on a computer trackpad, and it appears on an LCD screen.

When you're done, press a button and the screen is erased. Add a rechargeable battery and an enclosure, and you have unlimited (and eco-friendly) note-making capability. The project does require some computer code to drive the LCD; you can copy it here. If you can just remember that, you'll be good to go.

TIME: 7 HOURS

DIFFICULTY: HARD

COST: $175

PARTS

Post-It

Luis Bruno

STEPS

  • 1 Solder wires to the trackpad's [A] PS/2 connector.Connect them to the mouse coprocessor, which translates finger movements on the trackpad. Connect the coprocessor to the microcontroller [B] so the program code can generate an image on the LCD screen [C].
  • 2 Follow the data sheet instructions on sparkfun.com to attach the voltage regulator and electrolytic capacitor to the screen. This adapts the screen's power to the right level.
  • 3 Plug the screen into the carrier board. Solder resistors to the board, and connect them to the microcontroller. Power the board by connecting pins to the voltage regulator.
  • 4 Download our code for the screen at popsci.com or, if you substitute other components, from sparkfun.com.
  • 5 Install a nine-volt battery. Program the microcontroller with the code from your PC. Test the device's operation, put it in a custom-built box, and forget about those sticky notes. (NB: Screen image in above picture is simulated.)

_NOTE: A BASIC Stamp BS2 microcontroller is way too slow for adequately driving this project. The microcontroller used in this project was salvaged from an old Parallax Boe-Bot robot kit. Better performance could be obtained from AVR or PIC microcontrollers. In retrospect, I wouldn't even consider using a BASIC Stamp for this project. If you do, you'll be disappointed. Therefore, please consider this PBASIC code as a "starting point" for building a better digital notepad.

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