a Radio Shack PC board (solderable breadboard) with a triple-pad IC
layout. It turned out to be, essentially, an Arduino Duemilanove clone,
complete with headers for plugging in shields. The result was more than
satisfactory, but I needed a denser parts layout this time.
I wanted a Hackduino that would run at 3.3 volts (but retaining 5 volt compatibility),
which would permit direct interfacing with 3.3v sensors and peripherals
(and with a Raspberry Pi!) without having to use level shifters.
It would be also be nice to have an on-board plug-in socket for a Nokia 5110 display,
since that (allegedly) runs on 3.3v. Headers for shields were superfluous because I
already had laying around quite a number of factory-built Arduinos that
would serve that purpose. Result: a tailor-made special purpose Hackduino.
Let's call it a Hacduino.
I build this one on a stripboard and that proved to be more suitable
than a solderable breadboard for a dense and efficient parts layout.
It's especially useful when there are terminal points with multiple
Features of the Mark II Hacduino:
- On/off power switch
- Switchable between 3.3v and 5v to the Vcc buss (& voltage indicator?)
- D13 LED can be enabled/disabled by a jumper
- Wired on-board socket for a Nokia 5110 monochrome display
- Uses standard (cheap) hole-through ATMega328 chip
- Highly customizable -- can optionally add extra header strips for power and I/O.
An ATMega 328 powered at 3.3 volts with a 16 MHz clock is running out
of spec. Effectively, it is overclocked. I have not had any problems with
this, but I certainly would not run an overclocked CPU on mission critical
projects, such as controlling industrial machinery or even home automation.
For hobby purposes, it should be just fine, though.