I have been working on a miniature, low power wireless remote node based on the ATmega32U4 MCU (the same used in Leonardo Arduino). This is a Open Source Project, all design files and documentation is available here: [OBSOLETE] Funky v2 – Martin's corner on the web.
I wish to say that I am amateur, only started learning electronics on hobby level recently.
The highlights are:
2*2 cm in size, only few mm thick
can be powered from a CR2032 coin cell
0.04mA @ 3V in sleep mode
Programmed via the USB - just like Arduino Leonardo
Has a RFM12B radio module for wireless communication with other sensor nodes or another node acting as a gateway (logging the data or forwarding it to the Internet)
Option for on-board voltage step-up boost regulator
I build these by hand using hot air gun - a slow process, but the outcome is beautiful:
Nice work. I'm wanting to do something similar with the mini-pro... where I put in pull down resistors on 6 of my digital inputs.... and then voltage dividing resistors for 4 or 7 (application dependent) 3mm LEDs. Of course I can punt the resistors if I go with the 8mhz 3.3 variety.
I want to permanently mount an RJ45 header for the inputs (I'll run power, 6 inputs and a spare down a section of Cat5e to my devices in the field) and a 9v power header for power. The inputs would of course also need a pull down resistor to ground.
Then I 'd need 10 additional pins that I just connect a ribbon cable to, in order to accommodate the interface elements mounted on a small board on the enclosure (buttons, LEDs, etc...).
I'm also impressed with your camera , it picks up the laser pitting. ]
I just made a carbon skirt for an mcu to help a friend, basically a little frame with extra connectors.
I think this great!