Modern Blinkenlights

From: Chuck Swiger <cswiger_at_widomaker.com>
Date: Fri Jun 18 16:09:26 2004

At 08:13 PM 6/18/2004 +0100, you wrote:
> > 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

The only Linux cpu load/led display projects I could find work as Tony
described .
ledstatus-0.1.tar, meter-0.2.tar, and qmeter-1.0.tar all use one led & a
resistor
on each parallel port line D0-D7 (two leds not used).

Which is disappointing because I wanted to use a big old analog radio meter ;)

--Chuck
Received on Fri Jun 18 2004 - 16:09:26 BST