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PIC / PICAXE-controlled LED Beat flasher

J

John Barrett

Jan 1, 1970
0
I know nothing about doing that, I would like to learn to use CPLDs or
FPGAs whichever is the best thing right now, seems like it might be CPLDs.

I've taken a couple of shots at it using some of the vendor provided
development tools -- schematic capture + simulation + compiling

It always came down to "too complicated for gate level logic -- use VHDL"
and I've never had the time or motivation to learn VHDL, so I ended up using
PICs and AVRs instead.. throwing lotsa little chips at the problem instead
of one big integrated chip :)

The other problem I have with CPLDs and FPGAs is the newer devices are too
much for in-house programming -- you have to send off your design to the
vendor and they send you back loaded chips to test with -- usually they are
pretty good about doing that free the 1st few times if they think you are
going to market -- but after that -- you pay per chip at a steep markup
because its a one-off job for them.. not a production run

The ones that you can program in-house are relatively limited -- I dont
think any of them are up to doing serious SOC work -- not enough gates

(unless something has changed in the year or so since I last messed around
with using CPLD for a project)
 
R

Rich Grise

Jan 1, 1970
0
all 3 banks act identically as a 0-10 level meter when a given bank is
enabled.. when a sufficiently strong pulse of sound is detected, then
the meter function switches to the next color bank -- this makes the
multiplex idea especially attractive since it seperates color selection
from level meter code, and enables the level meter code to work
correctly no matter what color is currently selected. the level meter
code will not have to be aware at all of the current color selection.
(with the direct drive, the level meter code would have to use a
different set of I/O pins for each color.. with shift registers -- well
thats just getting overly complicated for something like this)

It sounds like you want a bar graph "VU" meter that pulses with the THUMP,
thump, thump, thump, THUMP, thump, thump, thump, and on a particularly
large "THUMP", switch to the next bar graph, track the next few thump-
thump-thumps until a big one comes along, switch to the next bar graph,
and so on.

Is that about what you're saying?

You could do this with an LM3914(?) with the banks' cathodes parallelled:
__________________________
| 3-bit shift reg. |
Trig ---| + hi-side driver |
|_________________________|
| | |
R G B
| | |
[red [green [blue
anodes] anodes] anodes]
| | |
3914 outputs | | |
10 -> cathodes x--------x--------x
| | |
9 -> cathodes x--------x--------x
| | |
8 -> cathodes x--------x--------x
| | |

and so on...

With a threshold detector or something to trigger the shift, or
maybe just another diode (or diode OR) from level 10 or 10 & 9,
to shift the active column.

Good Luck!
Rich
 
J

jasen

Jan 1, 1970
0
Thanks again, although I need to be able to independently control 30
different LEDs. Either I didn't explain this clearly .. or.. do AVRs
really support 30 seperate outputs?

the ones with 44 pins have more than 30 outputs available.

Bye.
Jasen
 
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