@Mark_Kriegsman Single SOIC package ATtiny85, one decoupling cap, one 10K reset pull-up, and a switch wired as a pull-up (correction: active low, meaning it’s pulled up and goes low when pressed) with matching 10K resistor. The 2x3 header is simply there to show how you’d connect it for programming through ICSP. Still 20mm x 10mm.
I need to figure out the pin layout on the strip side. It may not be VCC/SCK/MOSI/GND … so a little bit of swapping around might be in order.
That’s darn slick.
If the spirit moves you, I’d love to see a design with an ATmega32U, w/ on-board USB.
I take it you do a lot of this? 
Oh, @Zeke_Koch too …
@Mark_Kriegsman Do a lot of what?
Board design.
The 32U4 in TQFN package is already 12mm square, which will make the final width wider. In QFN however, it’s 7mm square so that’s certainly a possibility.
Yep, I do tend to design a lot. I’ll see what I can come up with a 32U4.
Niiice! I’d snag a couple
Of this tiny85 design? I can run a few boards through my usual culprit and get some made, sure. Was wondering if I should try an MLF package instead, as much as I don’t like working with them, but it is smaller than the SOIC one.
Very clever way to do the icsp. I like it!
yeah that’s neat! I just use test clips (I also have SOIC ones) so that should save the end bits…
Yeah, adding the headers for your clip would make the piece wider, unless you put it right on the IC.
There’s another way which involves pressure pads, but you need to make a special header for that. A 2x3 you can get anywhere.
Ah so the pcb is wide enough that the headers can fit in by pressure. That’s cool. I’ve been just using the test clips on the ic directly. I haven’t tried it with the soic, but it’s been easy with the dip ones.
This really is a brilliant use of header pins. I’m totally not an expert, so for all I know everyone does this all the time, but I’ve never seen it before myself, and it makes me smile at the ingenuity.
Yeah, totally love it
Almost. Standard PCB thickness is 1.6mm and the pins are 2.54mm (0.1"). When you take into account the pin thickness itself, you end up with a gap of about 1.8 to 1.9mm between pins. What I do is bend the pins slightly so they look like this Google Workspace Updates: New community features for Google Chat and an update on Currents and it gives me just enough pressure to slide the card in between and make good contact with the pads. Keep in mind that the amount of space taken up by those pads is equal to simply putting a 2x3 through hole header. I just like to do this instead so I don’t need to either solder a header on or build a pogo pin rig.
You can also get a card edge connector like this one http://www.mouser.com/ProductDetail/HARTING/15110062601000/?qs=sGAEpiMZZMvffgRu4KC1R5Zs/Wqu3YOcIY2Go2iJE/Y%3D and build it up on a PCB with respective wires and what not. But now you’re incurring more cost to make a custom connector and what not, whereas those 2x3 header are dirt cheap and easy to get. Just solder the necessary wires on one end.
You can also do it like this person did it, with spring loaded contacts http://www.daniel-spilker.com/blog/2011/04/25/isptouch-for-avr-microcontrollers/ or, if you still want to make something custom, use pogo pins.