
Clock Edge Detection in Excel - gk1
http://www.drdobbs.com/embedded-systems/clock-edge-detectionin-excel/240169084
======
sliverstorm
_I 've always said that anyone working on an electronic system really needs an
oscilloscope. Without it, you are effectively blind and just guessing at what
the signals on a PC board or on a wire look like. When I first started (a long
time ago), those images were mostly transient._

Really? All the scopes I've ever used have had capture modes (although I have
never used truly antique scopes). While I forget what the function is called,
the scope would trigger on an edge, capture the waveform and freeze it on the
screen. Now, this only ever fits a handful of bits (maybe 3-5 ASCII letters)
onscreen, but it was really helpful for me. If you wanted to capture data in
the middle of a long stream, you could use a second probe for the trigger, and
in your code fire a single edge on a secondary pin right as you send the data
you want to capture... lot of cool things you could do. Even the old analog
scopes are amazingly powerful. I highly encourage anyone doing much scoping to
do their best to _master_ it.

But anyway, back to the subject at hand, I just thought I ought to point out
to those who are getting into this sort of thing that Logic Analyzers exist
for exactly this purpose.

~~~
HeyLaughingBoy
Capture functionality was very expensive, and thus uncommon, until about 15
years ago. It was around that time that Tektronix came out with their low-end
TDS200 model scopes starting at around $1,200. That was an amazingly low price
at the time.

My analog Tek 442 is probably about 25 years old and still going strong. I
hardly consider it antique.

~~~
sliverstorm
Ah, excellent context. Most of the old scopes I used were at my University,
which probably gave me warped perspective, as they were always able to afford
the good equipment.

------
acqq
One wonders why the author bothered to make cell formulas in Excel for 500k
rows when he used awk afterwards to process all the rows anyway. Spreadsheets
are convenient tools, but his formulas seem to be fully awkable? He used two
values from the previous row but that is only two variables more.

------
robomartin
OK, well, clever, but these days it's easier to buy the right tool for the job
or use some thing like a simple FPGA demo board. Even the simplest Xilinx
Spartan on a cheap eval board can be programmed quickly to decode just about
anything and provide you with real time live data for debugging something like
a serial interface. The approach he presents is laborious and far from real
time.

------
Animats
Analog scopes could not freeze anything on the screen, unless you had one of
the expensive Tektronix scopes with a storage CRT. Most modern scopes that
look like analog scopes are really computers front-ended by A/D converters.

