[time-nuts] IRIG-B with Arduino

[John Miles]

> Fellow clock-tickers,
>
> 	I'm finally starting to learn microcontrollers, and have
> selected Atmel's AVR line as my tool of choice. I've also
> discovered the Arduino site, and am starting to learn their IDE as well.
>
> 	My first goal will be an open-source/open-hardware IRIG-B
> decoder (takes IRIG-B 1kHz stream, sends the timecode to an LCD
> panel). I've noticed a distinct lack of hobby-priced decoders on
> the market, and I intend to try and remedy that.
>
> 	My initial development platform will be the Arduino
> Mega-2560 board. However, that particular microcontroller is
> unlikely to be my final chip of choice due to the fact it's not
> available in a hobbyist-friendly DIP package. If others with more
> development skill have suggestions for a different chip, I will
> gladly listen.
>
> 	Stay tuned for further developments (no pun intended). I
> expect this to take at least a few months, as the learning curve
> looks kind of steep.

That's a good family of parts to start out with.  It is very well supported
and easy to work with.  You don't really need to mess with the Arduino IDE
and all the trimmings -- just set up AVR-GCC with WinAVR or one of the newer
distributions and go from there.  If you have ever done any C programming
before, the learning curve will be measured in hours or days, not months.
If you haven't, well... there's always assembly.

There is a new low-cost kit with Arduino-like USB programming capability on
the market:
http://www.seeedstudio.com/depot/usnoobie-kit-p-708.html?cPath=104_128

The first batch of these shipped with broken bootloader code so you have to
have an STK-500 or similar programmer to get them up and running.  I imagine
that's been fixed by now, but at any rate, the Atmega328P is probably the
chip you want, if you want a higher-end AVR controller that still comes in a
DIP.

I just rigged one of them up to drive a YIG synthesizer:
http://www.thegleam.com/ke5fx/stellex.htm (see December 2010 update at the
very bottom of the page).  Apart from the USB bootloader confusion and the
presence of a couple of spurious error/warning messages in the avrdude.exe
programmer utility, I'd give it two thumbs up at a minimum.  Great little
device.

-- john, KE5FX