Build It: The Electronic Post-It Note

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

By Dave Prochnow Posted 03.11.2008 at 11:56 am 6 Comments

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

(1) LCD + carrier board (SparkFun Electronics #LCD-00569 + #LCD-00600; $19.95 + $18.95)
(1) Trackpad (Electronic Goldmine #G1283; $1)
(1) Microcontroller (Parallax #28803; $99.95)
(1) PAK-XI Mouse Coprocessor (AWC #PAK11; $23.49)
(1) 3.3V voltage regulator (SparkFun Electronics #COM-00526; 1.95)
(1) 10mF electrolytic capacitor (SparkFun Electronics #COM-00523; $0.45)
(4) 10K resistors (RadioShack #271-1335; $0.99)
(1) 9V battery $3 (available locally)
Hookup Wire (RadioShack #278-1224; $5.99)

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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6 Comments

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jhickner

03/12/08 at 5:45 pm

The propeller, also from Parallax, would be a great basic stamp replacement for this project. And at $20 for the proto board, it's a lot cheaper too.

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ford2go

03/13/08 at 1:04 am

This is the 3rd time I've tried to comment on this -- maybe this time your comment button will work,

Anyway, the tech here is fine. Well... the author admits that the hadware is slow, but the concept apparently works.

In practical terms, it seems to be like a WIndows Vista toaster -- sure, you could make one, but why would you.

Fisher price makes a toy that does this function. It consists of a grid of cells containing metal particles and a thixotropic liquid. (think mayonaisse). You use a magnetic stylus to bring the dark colored surface of the cell -- allowing you to write or draw. The metal is held in place by thixotropicity (all right, I made up that word).

There is also a slider to 'reset' the display.

Works pretty good-- costs 8 bucks or so!

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russosv

03/13/08 at 4:17 pm

This is a cool project, but very price restrictive. Jhickner makes a fantastic point! The Parallax "Board of Education" is way overkill for this project... the Propeller board looks like a perfect substitute; and from what I understand it already decodes PS/2-- so you can leave out the PS/2 decoder chip as well!

That will cut down the cost of this project to around $75, which is much more feasible than $175...

Another thing you could save $$$ on would be the LCD-- if you're only using the 2 colors there's no need for a full color LCD. Sparkfun sells a B&W 128x64 LCD for only $19.95 with a built-in controller. That would shave another $20 off the price.

Sparkfun B&W LCD:
http://www.sparkfun.com/commerce/product_info.php?products_id=710

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lukeandangela

03/26/08 at 3:39 pm

Even though it would be huge, is there a way to do this with an old laptop? What extras would you need past a laptops screen trackpad motherboard etc...

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mindstrm

04/14/08 at 11:57 pm

Where are the instructions to attach the voltage regulator and electrolytic capacitor to the screen??? All the article says is Follow the data sheet instructions on Sparkfun.com to attach...but there is no link or url locations and I cannot find anything about it...does anyone know where I could locate this? Thanks...you can email bweibling at (@ not used for spam purposes...) gmail.com thank you again!

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spleemyster

08/18/08 at 4:59 pm

Well i think this is cool but if you r some one like me couldnt you just take a laptop mother board take wht you need off and hook up a smart pad and wht ever you call it

and i would need a huge screen