smallest arduino board?

I was annoyed by how breadboard-unfriendly all of the arduino boards I could find were (even the nano covers up two extra rows of holes), so I decided to see how small I could get one. I also did not want to use any smt components because my soldering skills are nothing to write home about.

This is what I came up with. I used a wire wrap socket to connect the atmega168 pins directly to the breadboard, and used a piece of perfboard with circuitwriter traces to put the external components in the space under the chip. The schematic is very similar to the dorkboard, but it uses an ftdi header (works with my 5V-modified FTDI basic breakout from sparkfun) for programming.

The board fits over the gap in a breadboard without taking up any more space than a bare atmega168, and the total footprint of the board is only .18 square inches more. It does not have a reset button or on-board power regulation, but I've been playing with the design in Eagle and I think that if I extend it out to two inches and don't have to draw the traces by hand, I can make it feature-equivalent to sparkfun's arduino pro boards.

Sorry for the blurry pictures. I don't have a macro lense, and this thing is small.

I think it is still bigger then the arduino mini pro from sparkfun. you can probably beat that device in size if you go with an smt package for the mega168 without power.

Nice board though

The pro mini is .7x1.3 (covers 3 rows on a breadboard), that's .91 square inches. This one, at its widest, is .6x1.7, but the footprint is only .74 square inches, so I suppose it depends on how you measure. This one certainly leaves more space available on the breadboard.

Cool!

Smallest DIP based Arduino I've ever seen. Do a writeup on the playground? ::)

I’ve been playing with this design for a RRBBB, but it’s clear I have slightly different goals (I was less interested in breadboards and more in “runtime board” like functionality with pads to attach to. And I was less worried about the (relatively large) SMT components on the bottom, or being able to “easily” attach a programming cable.)

Did you mean to connect AVCC to ground?

Edit: oops, misread it, it's the pad next to AVCC that's connected to ground. That makes a bit more sense...

Sparkfun pro mini and a 28 pin dip socket.

For reduced size on a breadboard smt isn't going to help that much. The smt mega168 is about the same width as a dip socket and you need extra space to break out the pins.

Don't forget this one, from the guy who sorted out the serjtag package:

Who needs a board? :)

Version 2!

This one adds a voltage regulator, a reset button, and a few other minor changes. It has everything the Arduino pro mini has except the power indicator led (not enough room to hand-route the 5V line). I also moved everything to the top of the board, except for the led, which makes soldering easier. The board is 2 inches long, .9 square inches.

Better photos too!

Still using the internal oscillator, though?

No, both of them have 16 Mhz ceramic resonators.

Here's a schematic for the second one.

what are you using to draw those traces on the protoboard?

I used a CircuitWriter. It's a pen that writes with a conductive polymer. It's great for turning perfboard into a psuedo-pcb.

Once you've written a trace with that pen, can you solder onto it (better than soldering onto the bare fiberglass of the protoboard)? I don't think I'd trust an ink trace, but it might be a handy soldering aid if that works.

I avoid drying to use it as a solder pad (I use the copper pads on the board instead), but I have noticed that solder likes to flow over the traces if I use a little too much. Also, if I have to remove any solder, the desoldering braid usually picks up some of the circuitwriter material, and I have to re-apply (which can be difficult with components soldered as tightly as in this project.

Even so, the stuff works surprisingly well. I wouldn't use it for production, but it's the best thing by far that I've found for making a circuit board without waiting (and paying) for a real PCB to be manufactured.

Its also great for hacking existing circuits. I used it to modify my ftdi board to output 5v (right before they took my advice to add a solder jumper for that purpose ::) ) and my breadboard power supply to add an unregulated output.

geez, live and learn. I’ve been bent over my perf-board soldering in twists of wire to join comonents when I have a fine new jar of wire glue I could have tried! Tomorrow for sure.

By the way, could you find a way to get a clearer picture of the board? Do you have a scanner? Sometimes they can do a nice closeup.

The pictures for the second one weren't that bad, where they? I thought about trying a scanner, but I didn't think to take pictures before everything was soldered-in and working, and the wire wrap pins stick out too far for a scanner to be useful.

I decided to get a couple of these made by BatchPCB, and they just shipped out from their facility, so I should have those to show off in a couple of days.

New picture time!

I've made some minor modifications since I ordered these, mostly playing with the fill geometry and silkscreens, and adding a solder jumper for disabling auto reset and an icsp header. The green LED is the standard D13 indicator. The blue one is a power indicator, but it uses D13 for a ground so that it's easier to discern whether the D13 led is on (they can't be on at the same time). The bottom fill is ground, the top one is +5V. The board is two inches long, and the ftdi header sticks out an additional 1/4 inch.

Oh, and any warping in the photos is a side effect of trying to avoid blurriness.

I love how you managed to fit a bunch of components under the socket. Great use of space!