Modern Blinkenlights

From: David V. Corbin <dvcorbin_at_optonline.net>
Date: Sat Jun 19 08:39:08 2004

>>> -----Original Message-----
>>> From: cctalk-bounces_at_classiccmp.org
>>> [mailto:cctalk-bounces_at_classiccmp.org] On Behalf Of Tony Duell
>>> Sent: Friday, June 18, 2004 3:13 PM
>>> To: cctalk_at_classiccmp.org
>>> Subject: Re: Modern Blinkenlights
>>>
>>> > 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 conversion from digital to analog and back provides second order
effects. Your design (straight off the original bits) is simplistic. The
modern world requires overcomplication in all things <....ducking and
running....>

David
Received on Sat Jun 19 2004 - 08:39:08 BST