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Topic: 1hz clock (Read 4334 times) previous topic - next topic

Mori

an ATtiny and an external 8 or 16 Mhz crystal could do it (Set it up to pulse every second)
Memento Mori
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baum

I am going to end this topic and start a new, more specific one. Thanks for all the help!

CrossRoads

Yes,
Feed 64 KHz into CCLK, RCO from stage 1 into stage 2, RCO Pulse from will yield a low going pulse 1/64K wide 1x a second.

http://www.eetkorea.com/ARTICLES/2001SEP/2001SEP06_AMD_AN.PDF
See figure 3 for suggestion on getting 64KHz source. Other ways also possible, this seems pretty straight forward.
http://www.z80.info/uexosc.htm
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

baum

#18
May 25, 2011, 11:42 pm Last Edit: May 25, 2011, 11:45 pm by baum Reason: 1
Quote
seems pretty straight forward.


Not as easy as I would have hoped, but I guess it will be fine. For the first link, they don't specify where the output is...any ideas?

Also, is there a way I can get 50% duty cycle?

CrossRoads

Enable the outputs, and use the MSB, which will change hi/lo/hi/lo every 1/2 second.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

baum

right...

how exactly do I setup the crystal though?

baum

I want to connect the 65.536kHz crystal to the clock of a binary counter. no microcontrollers involved.
Thanks!

CrossRoads

Reply #24 has circuits to make the 64K oscillator that will drive the clock line.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

baum

But which would should I use? There are three on that page.

baum

My counter chip is a 74393, i will be running the power supply at 3V (2x AA) and I will be using this crystal.

baum

Whoops. Then how about 3x AA, which would be 4.5V?

baum

Whops again.... I meant to say 74HC393. :( Sorry for the confusion!

CrossRoads

Try the simplest one first baum, if that works then you're all set.
If not, try another.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

baum

So the second one w/ 3 inverters and a 100N cap?

CrossRoads

I would have suggested Figure 3 from this link first
http://www.eetkorea.com/ARTICLES/2001SEP/2001SEP06_AMD_AN.PDF
1 inverter, couple of 22pF caps, couple of resistors.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

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