Re: PATCH : LEDs - possibly the most pointless kernel subsystem ever

From: "Herbert Pötzl" <herbert@13thfloor.at>
To: Marc Giger <gigerstyle@gmx.ch>
Cc: linux-kernel@vger.kernel.org
Subject: Re: PATCH : LEDs - possibly the most pointless kernel subsystem ever
Date: Wed, 30 Jul 2003 21:05:25 +0200	[thread overview]
Message-ID: <20030730190525.GB7260@www.13thfloor.at> (raw)
In-Reply-To: <20030730205002.1e2a27bf.gigerstyle@gmx.ch>

On Wed, Jul 30, 2003 at 08:50:02PM +0200, Marc Giger wrote:
> Hi All,
> 
> On Wed, 30 Jul 2003 19:44:57 +0200
> Pavel Machek <pavel@suse.cz> wrote:
> 
> > Hi!
> > 
> > > > But this kind of blinkenlights needed pretty fast LEDs. (At 486
> > > > time I decided that parport on ISA is fast enough..)
> > > 
> > > I'll buy some LEDs and build a parallel port connected LED panel
> > > tomorrow...  Do you think the overhead of driving the LEDs would
> > > have too much of a negative effect on system performance?  If so, or
> > > if we
> 
> Yesterday I connected 8 LED's to the parallelport datalines. Today I
> read this thread. What for a coincidence...
> The goal of this "project" was to show the current cpu load. It works
> great now! I can see randomly the LED's lightening up while I am writing
> this mail:-))
> 
> > 
> > I'm not sure. At 486 days I was pretty sure it did not matter. These
> > days you might get 10% slowdown on some microbenchmark, or something
> > like that. I do not think it can slow down common tasks.
> > 
> > My construction of LED lights is extremely flaky, and I'm afraid of
> > burning printer port. At 486 days ports were expected to survive such
> > abuse. Not sure if todays EPP/wtf ports can handle that.
> > 								Pavel
> 
> At beginning I had some fear to connect LEDS directly to the parport,
> because its an onboard controller (like the most mainboards have).
> I don't notice system performance slowdowns. (CPU Load code was borrowed
> from xosview:-))
> 
> My personal goal would be to controll a Dot-Matrix Display. The
> Display should show something like the actual CPU temperature,
> CPU-load, processes, s.m.a.r.t state, etc etc etc etc..........But my
> problem is how to beginn with that. I would prefer to controll it with a
> PCI card. Also I looked today at 68HC11 microcontrollers, which I can
> connect to the serial port and transmit the needed infos.

sounds interesting ...

> Are there suggestions / comments / questions?

http://www.ewal.net/lcd.php
http://patrick.wattle.id.au/cameron/information/lcd/

> If somebody is interested to develop such a card / controller with me, I
> will be pleased to hear from you!

I'm interested in discussions and willing to share my
knowledge (was working with embedded systems) on this
issue ... 

best,
Herbert

> Thank you
> 
> Marc
> -
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