Re: gEDA-user: Power relay question

[Gabriel Paubert <paubert@xxxxxxx>]

On Thu, Jul 28, 2011 at 07:26:25PM -0600, John Doty wrote:
> 
> On Jul 28, 2011, at 7:03 PM, DJ Delorie wrote:
> 
> > 
> >> Or 4000-series CMOS logic. Nice thing about 4000 series in this
> >> application is that it can operate on unregulated 12V.
> > 
> > I thought of that, but a linear regulator just for the pic would be
> > cheap, and you get debounce, multi-input state machines, and a
> > watchdog for no extra cost...
> 
> Simple state machines and debounce are easy with MSI, too, and you don't need a software development setup. Arguably easier to debug a simple MSI circuit than a program.

Another way to implement it might be with a Silego GreenPak 
prgrammable mixed signal array:

http://www.silego.com/index.php?page=greenpak

It's cheap, and the programmin hardware + 50 chips 
is only $20 (+S/H) or so until the end of the month
(so hurry up).

For Europe, the S/H charge is a bit steep ($50), but even
then it's less than â100 for a programmer, 150 chips
and shipping plus handling.

The development software is only available for Windows 
and MacOS, sadly no Linux version :-(

I'm afraid that a 10F200 is a bit short on I/O (4 pins
for 2 sensors and 2 motors is really at the limit).

Personnally I started with 12F508 (IIRC) and then 
switched to 12F609 because of the capability of brown-out 
reset: otherwise switching power off and on sometimes
failed to perform a full reinitialization of another chip
(a synthesizer from the Analog's ADF4xxx series), when
the power supply dropped below the minimal voltage to
preserve internal configuration latches.

You may not have this problem, but this kind of very
intermittent failure is incredibly hard to diagnose:
it only happened if the power was switched off for
the right amount of time, and not on all boards...

	Regards,
	Gabriel 


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