[sdiy] tinyscope

[Cary Roberts]

>I was looking at arduino projects, as well as PIC >projects,
>and found some relatively simple oscilloscopes. Then, I also
>found some tiny 3 or 4 cm (ish) displays for relatively cheap
>(bout $20) (and these were full color, high res, etc)
>So, I'm thinking for the cost of a standard synth module,
>and for probably less work, a nice waveform display and voltage
>indicator could fit into 1u space. Has anyone else built
>anything like this?

I built one using a Luminary Micro LM3S3748 ARM Cortex M3 processor.
Luminary provides example code for an oscilliscope but you'll need to rework
a few bits to get the refresh rate acceptable for low frequency signals.
There's a video of it in action here:

	http://www.youtube.com/watch?v=ajSaMRAUXBg

Picture here:

	http://www.fdiskc.com/syn/ahba/2008/Ghett-o-scope.html

If you want reasonable accuracy you may want to forgo the internal A/D
converter and attach an I2S or SPI A/D to the microcontroller.  One bonus of
the Luminary parts is single cycle multiply and two cycle multiply
accumulate operations.  

Before you pick up a serial display I suggest doing the math for refresh
rate.  I'm using a parallel display and having no issue, but the serial
Nokia displays I looked at weren't acceptable.

I was considering doing a run of 100 of these but I don't want to sell
anything that will be rendered unusable due to a failed irreplaceable
display.  After my P3's OLED display lasted died after a year I'm skeptical
of any OLED display no matter how pretty.  The LCD I'm using is okay
(viewing angle isn't all that great) but there are so many variations in
controllers and pinouts it's impossible to second source without an
interposer board.

Anyway, if I were to ever get around to making a module here's what it'd
look like. (and the render on the screen is a real capture from the scope,
not synthesized)

Frac version:

	http://www.retrosynth.com/design/oscope/blacet_oscope.png

And a MOTM version:

	http://www.retrosynth.com/design/oscope/motm_oscope.png


-Cary