External timer

homesch00lkid

I am trying to do background timing with the BS2, such as running a loop until a minute has passed. I have a PWMPAL, so if I can get something to pulse every second I can count it with that. The PWMPAL itself cannot provide the pulse because I am controlling four motors with it. Any suggestions? It has to be EXTREMELY light weight for my pusposes, and hopefully it won't be too expensive.

Beau Schwabe

Is this a one time deal?

If so, how about hacking a AA battery mechanical clock module? Most hobby craft stores sell these
as a clock kit for $5 or so.

Here is a hack that I did ...the module produces one pulse every second with a 1.5V source.
I realize that you can't see much, but you can get a relative idea of size.

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Beau Schwabe - Mask Designer III

National Semiconductor Corporation
Latest Company News
(Communication Interface Division)
500 Pinnacle Court, Suite 525
Mail Stop GA1
Norcross,GA 30071

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Post Edited (Beau Schwabe) : 3/28/2005 2:24:10 AM GMT

homesch00lkid

That looks like it should work, but I only have 5V and 9V sources available. To regulate 1.5V might make it too heavy. Would it work with higher voltages?

Beau Schwabe

I just use a voltage divider of 2.2K and 1K to get 1.56V from a 5V supply. Remember the output is only 1.5V but plenty to drive
the base of an NPN transistor.

You might still want to explore your options, there are several timer chips to choose from that might be a better solution
for your application. The clock module hack was just something I did because I had one lying around that had served it's
purpose as a mechanical clock. I certainly would not spend the $5 on a new clock module just to hack it when timer IC's
can be purchased for much less.

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Beau Schwabe - Mask Designer III

National Semiconductor Corporation
Latest Company News
(Communication Interface Division)
500 Pinnacle Court, Suite 525
Mail Stop GA1
Norcross,GA 30071

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MacGeek117

A 555 would always work.
bugg

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Boe-bot: $229

Toddler: $249

Learning Google is your friend: priceless

allanlane5

http://www.rhombus-tek.com/co-processors.html

This guy has a nice 8-pin co-processor which will give you a mostly rock-solid 50 mSec square wave. He has techniques on his web-site to use this square-wave in order to implement a real-time counter on the BS2. You need 8-pins of space for the 8-pin DIP, and a place to plug in the resonator.

In addition, it gives you an RS-232 recieve port which will buffer up some characters -- but you don't need to use it for that. $11.50, I believe, for a very nice package.