18 Jun
2013
18 Jun
'13
4:35 p.m.
On 06/18/2013 03:44 PM, Dave Wade wrote:
For ONE LED all of these solutions are OK. So soon as you want 20 LEDS
at different frequencies you are into FPGA (or perhaps CPLD) territory.
Depending on total power consumption a typical FPGA will flash as many
LED's as there out-put pins at most any frequency that can be derived
from the master oscillator, typically 50Mhz. I think the FPGA is a
wonderfull device, and these days you can interface it your PC via USB
or RS-232...
Well, now I think you're just trying to get Tony's goat... :)
But MCU vs. FPGA is an ongoing argument for many applications with no
clear winner.
RS232 seems susceptible to getting popped. I think the
default
MC1488/MC1489 chips were very easily popped.Also RS232 is good for much
longer line lengths. When I worked at NERC (www.nerc.ac.uk) we had
several sites in the Thames Valley and the thunderstorms would follow
the river popping the driver chips on the way. There was a map in one of
the Radio Society of Great Britain hand books showing the desnity of
thunder storms. The Thames Valley figured high on that as well....
I know that the 1488/1489 combo was popular, but the lead engineer on
the comms project at the time that I was involved insisted that the
75150/75154 combination was much superior. I don't recall what his
reasoning was, but we didn't run into any popped 7515x parts that I can
remember.
--Chuck