Picture of USB PCB Business Card
DSC03152 (Small).JPG

This is a business card that will type out some text when you plug it into a USB port.

It uses a ATtiny85 microcontroller with V-USB based code to emulate a keyboard. The typing is triggered by the CAPS LOCK status LEDs being toggled 3 times.

This instructable will focus on using CadSoft EAGLE to create your own USB PCB business card. I want you to be creative in the design, so some minor steps I've taken may have been omitted.

Code download is provided on step 8.

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Step 1: Circuit

Picture of Circuit

The circuit is based on V-USB's recommended circuitry. It's powered by the 5V from the USB port. There's two 68 ohm resistors, one on each of the USB data lines, these act as terminating resistors which suppress reflected signals. There is a 1.8 kilo ohm resistor on the D+ line, which allows the computer to detect when something connects to the USB port, and it identifies the device as a low speed device. Two Zener diodes with Vz of 3.6V are on the data lines to clamp the voltage on those lines. There is a 0.1 uF capacitor between the 5V and GND as a decoupling capacitor.

Since the business card should be a compact and thin design, 0604 surface mount packaging is selected for most of the components. The diodes are Mini MELF packaging (they look cool in my opinion).

The microcontroller is an ATtiny85, which is a 8 pin AVR microcontroller. The SOIC package version is chosen to keep the design compact and thin.

To program the microcontroller, in-circuit serial programming is used, which requires the signals: reset, SCK, MOSI, MISO, along with power and ground. The SCK and MOSI are exposed by the USB connector, while two pads are provided for the MISO and reset signals. This allows for a programming adapter to be made.
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Marc_Escobaem made it!1 month ago

Thanks for this Instructable! Made it and will use it for my applications!

ntsagarides1 month ago

That is a great and impressive idea but I have a v1.1 idea.
You could cut a rectangle on the PCB to the place where the IC sits and solder the IC dead-bug style so that it doesn't stick out that much. Of course the rails would need to be adjusted a bit to match the new layout.

Hello There, this looks great and I want to make something similar but cant find the eagle pcb file. Am I missing something here?

amuralha6 months ago

Can I program the attiny with an arduino?

This link explains how:

Tangoforce2 years ago
Very cool idea. Just one quick question please, is it possible to make a custom flash drive like this instead of using a microcontroller?
Eonir Tangoforce5 months ago

Of course, it is possible, but iIt would be much harder, depending on your requirements.

In this project, the micro is acting as a HID keyboard, which is very simple once you have the right library (V-USB). But to make it act as a USB drive, you would of course need something much different.

The easiest way to achieve this would to find an open source schematic of a USB flash drive and redo the layout into the form of a business card. It would be much more complex.

Can you please fix your schematic as it took me over 10 tries to finally realize that the pin #s are wrong. Other than that great project.
and what is the correct one? was the schematic fixed? thanks
Jan_Henrik11 months ago

This is more then Awesome!!!

Just a question. Could ou do the same with this but make it hold down a key for the time its plugged in? and how small could you make it?
frank26080115 (author)  hornbadoing1 year ago
I can make it hold down a key, but it will keep being held down even if you unplug it, or at least in Windows it will do that, I'm not sure about Mac or Linux.

Size has nothing to do with this.
jgidel2 years ago
Your circuit and you description of the circuit are different. Could you please add a corrected version of the circuit to your instructable. I like the idea and want to try it but I can't get it to work.
verence3 years ago
Very nice Instructable and a very nice product - although I would never plug an USB device given to me by a stranger into my computer (neither private nor at work).

But at an interview, the idea and the quality of execution alone would mean something.
frank26080115 (author)  verence3 years ago
People are afraid that it'll do "rm -f /"

I could also (in theory) open up a web browser using a multimedia key and then visit any URL
Give them a regular card with a URL on it. If they say that they don't have internet or their internet's down, give them one of these.
I'm amazed that nobody has asked, but can you please elaborate on the use of the vibrator on the soldering iron? Being a teenage lad, it isn't really the kind of thing I just have lying around in a cupboard or whatever!
frank26080115 (author)  lukestanmore2 years ago
it's a joke, the joke is that SMD soldering is so easy, you can even do it while holding a vibrator
Ahhh! Right, that makes sense now! I was thinking it was something about making the iron bounce off of the board for a split second so not to over heat anything! Great instructable though! I might have to try it!!
laxap3 years ago

frankly, this is an awesome project. The ideas to (1) use an HID profile, and to (2) use capslock to "talk" to the card are just terrific.

I'm sure you impressed your card recipients.

You totally deserved your 1st prize in the USB contest. Did you get your HP TouchPad? What will you do with it? hack it?

frank26080115 (author)  laxap3 years ago
Hi Pascal

Thanks for the kind words.

I didn't get the HP Touchpad because it was being discontinued, I received a prize of equivalent value instead.

On a somewhat related subject (since now people are hacking the HP Touchpad with Android), I did recently get my first ever smartphone, a Samsung Galaxy Infuse 4G, running Android 2.3. I also got a Micropendous. So I am completely ready to start hacking with Android ADK.
Did you end up hacking the ADK??
I really appreciate your effort to show how easy it is to solder 0603 SMT ... honestly I do. Great job! However... it's still wrong on so many levels ;-) Great Instructable!
Hey there! Pardon me if i missed it, but what is the cost of these per (1) assembled at home. And what would it cost to have these manufactured?
xa43 years ago
Very cool !! thank's a lot for sharing
Yandle3 years ago
Very awesome! ... .. Vibrator... #$*%ing PRO!
sdtrent3 years ago
What happened to the picture of the USB connector? It was cool to see the details on the pcb layout. Perhaps I am missing something. It looks like you can download the files to do the project yourself but I cannot find the file for the pcb.
frank26080115 (author)  sdtrent3 years ago
Thanks for bring this to my attention, I've formatted my Instructables in HTML and they seem to have disappeared, causing most of my pictures to be missing.


I'll add the PCB file soon.
hornbadoing3 years ago
im not that good with computers.. is there a way i can do that with a flash drive??
Nobody answered my question so i went searching.. the answer is yes you can do it with a flash drive. its actually pretty neat and u don't have to be a genius to do it.
c.klomp3 years ago
how does one get his hands on one of these? its awesome!!
BeefyHaze3 years ago
Wow, thats pretty slick but people might shy away and think that you are controlling their computer... Ive done things like this and some of the more computer illiterate freak out and shout "VIRUS" great design though
husamwadi3 years ago
SDgeek3 years ago
I can't help but do a double post here...Using this for handing out a resume is an instant job offer in my opinion.
WOW!!! Never thought of that... but I just found this so it's too late for me.
thoraxe3 years ago
That is godly bro, +1000 internets to you.
Franzjr3 years ago
Felicitaciones un excelente proyecto, Congratulations, one excelent project
Nice job, I like it a lot!!
I sincerely hope this wins first prize. You deserve it!
ryanlg3 years ago
Can you please supply the full specifications on the diodes (Forward voltage, etc) or a product code.
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