18 Jun
2004
18 Jun
'04
7:13 a.m.
I've seen a pretty easy-to-build circuit to put
one of those on a
Linux box. I remember something about a simple resistor ladder
network D-A and an LED bargraph chip from Radio Shack. The software
just puts the load on a spare parallel port, so it's pretty low-impact.
Are you serious? If so, I have to wonder if anyone can actually _design_
any more, or if they just throw standard modules together and hope it works.
Let me see if I understand this. You have a digital value (system usage),
on a digitial machine (the linux box). You convert it to analogue. You
then re-convert it to digital with a very low-res ADC (the LM3914 (I
guess) bargraph chip. Why not just output a suitable value on the
parallel port (which has 12 output lines IIRC) to directly drive the LEDs
(the 3914 drives 10 LEDs at most).
-tony