Saturday, July 18, 2015

Postage Stamp Micro-controller

In a previous post I described a little one inch square micro-controller based on the ATMega328 which I decided to build in order to learn KiCAD.  I have the boards back from OshPark.

To my way of thinking, it is a pretty good bargain to be able to obtain this lot of boards for the grand total of $10 plus shipping.  In any event, I have built up one of the units as seen below.

I have a couple of errors I will need to fix.  The first is that the row of header pins on the left and right side are not quite on 0.1 inch centers.  I plugged the headers into a prototype board while soldering and they both bend towards the centre of the board, so I need to space them a little closer together.  Oops...  The top and bottom headers are mounted on the top side of the board to allow plugging the board into a prototype board and still having all pins available.  I would expect to typically hard-wire the board into whatever circuit it will be employed in and then mount it down with double sided tape.  This one however is for bread-boarding.

The second error is that I used the wrong footprint for the thru-hole crystals that I have on hand and so it cannot sit completely down on the board.  Oh sigh...  Easy enough to fix however and I will make those updates before I publish the board at

The ATMega328 chips are raw ones with no boot loader, so I will have to program them with the ISP header.  This can be done with another Arduino or any of the ISP programmers such as the USBTinyISP.  No boot loader is required on this device as there is no USB or other programming interface other than the ISP connector so therefore the entire flash is available for your code.


  1. Hi Jeff,
    Nice looking boards, oddly enough I was playing with AVRs at work today while prototyping a new design. I have to agree, OSHPark are a spectacularly good service, and they have great tech support too should you ever need it. I've done about 6 designs with them so far, some personal and some for work, they are always stellar quality.

  2. Thanks Wardy for your comments. I don't get to play with AVRs at work these days. Mostly, I am working with Freescale K60, K20 chips as well as Blackfin and ST microcontrollers. I like the silly little 8 bit AVR processors for a lot of simple projects. This one was created as a useful project while learning KiCAD. I think I will have a number of projects where I will use these. I want to get rid of the HC/49 crystal and use a much smaller SMT part, but I have a number of these on hand, so it will have to do.