USB Business Card

[carrigan]

Hey all, first post on the forums. I mentioned I was working on a USB Mass Storage Class business card in the last business card build posted (http://hackaday.com/2012/06/08/555-business-card/) and the write-up is finally done. It uses an LPC1342 for USB communication and an AT45DB081 for storage (a whopping 1MB). Source code and schematics are posted, enjoy!

http://graphsandwords.com/usb_bc.html

[leadacid]

That's really cool!

If you don't mind my asking, whats the unit cost going to be per "card"?

[carrigan]

Thank you for reminding me I forgot to put up the bill of materials on the site!

Heres a bill of materials for 10, which is what I'll be making. All components are shipped from Digikey and shown per part:

• The PCB itself ~$2 (Seeedstudio)
• LPC1342 - $3.65
• AT45DB081D - $1.61
• USB A connector 48037-0001 - $1.41
• 12MHz SMD Crystal 405C35E12M00000 - $.88
• Voltage regulator AP7313-33SAG-7 - $.35
• DTA114YKAT146 - $.58
• LEDs, Resistors, Caps - ~$1

The debug header (GRPB052VWQS) is not shown because after I flash each one, I plan on removing this so that there isn't a Jtag header making the whole package much thicker.

All in all, each one comes out to right around $10. Definitely not for handing out at networking events, but great for job interviews etc.

[UAirLtd]

You know the LPC1342 has USB bootloader code in ROM? You can flash the chips direct from USB. Take a look at the documentation for our Forebrain dev boards that use the LPC1343: http://www.universalair.co.uk/content/l ... re-windows

I can explain how to compile code for it, or you could just grab the template firmware from our site, it's designed for the LPC1343 but will should work with no problems with the LPC1342, other than a few minor changes needed.

[igor_b]

wow, that is so awesome.

you can also somehow make USB connector as a part of the pcb like on those small usb flash drives: http://www.fareastgizmos.com/entry_images/0408/07/Supertalent-Smallestusb.jpg.

[UAirLtd]

yeah, making the PCB into a shroudless USB connector is easy, just get your design on 0.093" thick PCB (you may need to add a little solder on the USB tracks).

[carrigan]

UAirLtd- Yes I know that there is a bootloader on the LPC1343, but I had to do development and not just production so the debugger was very useful for finding flaws in the program. Perhaps the next batch I make will have solder bridges to pull up pins 0_1 and 0_3 to activate the bootloader and save board space, thanks for the idea!

As far as the on board USB header goes- no cheap board fab houses I have found offer .093" boards at a reasonable price. If you are using the PCB itself as a connector, I've always heard that you should use gold PCB fingers, which adds even more cost. While I think that an on board USB connector would be incredibly tasteful and a great design, the cost for a small batch outweighed what it would add.

[UAirLtd]

You can get eletrolytic gold-plating kits relatively inexpensively, otherwise gold-fingers will set you back maybe < $1 per board in batch if you get it done by a PCB fabrication company. You should be aware that if you require more than 100 square inches of PCB, many professional PCB manufacturing companies will consider your design. Certainly the manufacturer we outsource PCBs to will do .093" boards at about 50% higher cost than standard (which normally goes at about $1 per square inch), but admittedly you'd need a fairly high volume.

Take a look at our LPC1343 library for our Forebrain dev board: http://www.universalair.co.uk/control/forebrain#guides, it's got some super-simple-to-use functions that you might find handy. The dev board has P0[1] conected to a button, and P0[3] with a pull-up to V_USB, so entering USB bootloader is as simple as holding the program button while hitting the reset button.

[EkriirkE]

As far as the on board USB header goes- no cheap board fab houses I have found offer .093" boards at a reasonable price. If you are using the PCB itself as a connector, I've always heard that you should use gold PCB fingers, which adds even more cost. While I think that an on board USB connector would be incredibly tasteful and a great design, the cost for a small batch outweighed what it would add.

Is there a problem with using a spacer on the non-contact side to thicken it up?