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USBmicroISP: The Beginning Steps of Dev

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USBmicroISP v1.0:  The Beginning Steps of Dev

I like small things.  I don't know why.  It's something about slimness, minimal living I guess.  I drive a Honda Civic, yes.

To develop for a micro-scale, wearable electronics project, you have got to have a smaller USBtinyISP programmer.  Take the guts of that ISP (in-circuit serial programmer) project (props to the original devs there) and put them in this amazingly small box?

Don't you just want to put something in there?
Just imagine if small things weren't a thing. You'd be wearing THIS:

Stacked, large circuit boards on a big Arduino Uno.
Do not try to wear this at home, kids.
Oh, the HORROR.

Anyways... Here's my re-design that is mostly based off Adafruit's USBtinyISP and USB tiny code & design.  I just wanted to...ah... improve it a bit.  

The Design

Smaller, uses micro USB instead of large printer one, and looks cool, too.  The design is mostly reduced to SMD components, which presents the programming problem:  how do you get the programming code on the programmer (program the chicken)?  I've got a few tricks up my sleeve (such as this one). ;)  Essentially, solder our SPI+PWR jumper wires from a FTDI board to the completed programmer, then remove the wires after verifying that it programs a target.  If I was mass producing, I'd use pogopins and pads on the programmer board.

Features (mostly new):

  • Micro USB connection to PC
  • SMD components, mostly
  • Very small form factor (35x35x15 mm)
  • 10-pin and 6-pin AVR programming cable headers
  • Buffered SPI programming to target
  • Removable jumper to utilize target power (if not using 5V target)
  • Red busy LED and Green USB good LED

The schematic: USBmicroISP v1.0
Schematic of USBmicroISP v1.0

The board layout: USBmicroISP v1.0

Top layer of board layout.

Bottom layer of board layout.




Caveats

Assembly is a bit tougher given the SMD parts, and not-so-easy programming.  Also, there is a bit of mechanical work to be done to the case: drilling and cutting the plastic for the micro USB, the cables, jumper and LEDs. Since the case is translucent, you could not drill holes in the top for the LEDs. Perhaps arguably a better product and cheaper parts, but more expensive on the assembly.

Assembly post to come once the OSHPARK order arrives!
OSHPARK order confirmation of 9 USBmicroISP boards for $21.


Once I'm done I'll have quite a few programmers to get started with, and maybe to sell.

Adios, muchachos!
~JWilly






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