Electronics > FPGA

clock recommendation for Xilinx XCR3064XL (3.3v) or Altera Max 7000s (5v) CPLD

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grips03:
Looking for a clock recommendation for Xilinx XCR3064XL (3.3v) or Altera Max 7000s (5v) CPLD

Clock will be 60hz. Would be cool if time high is same as time low. For some reason 555 timer does not like doing that.

thanks

JoeN:
Provide a clock of any value divisible by 60 and divide it down within the CPLD.  12.000 Mhz crystal / 60 = divide by 200,000.   Assumes you have the resources available.  It will give you a very accurate clock, as accurate as the crystal.

Something like this for 5V:

http://www.ebay.com/itm/Valpey-Crystal-Oscillator-24MHz-5V-VF70BHT24-000MHz-DIP-8-Qty-4-/400272426272
http://www.ebay.com/itm/FOX-F1100E-120-Crystal-Oscillator-12MHz-5V-TTL-DIP-14-Qty-4-/301139016306

3.3V, search it out.

Why do you need such a slow clock?

dannyf:

--- Quote ---Why do you need such a slow clock?
--- End quote ---

To build the world's slowest computer?

a 32Khz crystal + divider will work. Or a simple mcu.

grips03:

--- Quote from: JoeN on March 30, 2014, 07:03:33 am ---Provide a clock of any value divisible by 60 and divide it down within the CPLD.  12.000 Mhz crystal / 60 = divide by 200,000.   Assumes you have the resources available.  It will give you a very accurate clock, as accurate as the crystal.

Something like this for 5V:

http://www.ebay.com/itm/Valpey-Crystal-Oscillator-24MHz-5V-VF70BHT24-000MHz-DIP-8-Qty-4-/400272426272
http://www.ebay.com/itm/FOX-F1100E-120-Crystal-Oscillator-12MHz-5V-TTL-DIP-14-Qty-4-/301139016306


Its for a Sega Genesis controller to Intellivision console adapter. I built an arcade controller to Intellivision console last year. So in this project I need the to clock the Sega Genesis controller, like the Genesis console does and decode 4 lines. I think I have the decoding logic right. And now need to find a way to clock this thing like the Sega Genesis console did.


3.3V, search it out.

Why do you need such a slow clock?

--- End quote ---

SeanB:
You can make a 555 give a 120Hz output then divide by 2 in a 4013 chip to give 60HZ with equal on and off times quite easily. Otherwise a 4060 and use a RC oscillator to make some higher frequency and use the divider to get 60Hz.

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