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Jim Granville
05/20/12 16:38
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#187451 - ATF750CL for PT clocks
Responding to: Jason Arkwright's previous message
Jason Arkwright said:
Hi Jez,

I have cpld capability at my finger tips, namely the the 16V8,22V10 and the 32 macro cell ATF1502, all these devices are under about 2 to buy, but theres no rom available and a descrete rom(high speed) are available at a very high price, anything beyond the atf1504 is simply too expensive.

At the moment, I'm trying to design a dual modulus prescaler and I thought I'd nipped in the bud until I realised the 16V8 and the 22V10 do not support product term programmable clocks on their respective flip flops.The ATF1504 does however, still a big shame.


If you need PT Clocks, in a 22V10 package, just use the ATF750CL.

You can create SINE waves in CPLDs a couple of different ways.
Small PROMS are doable, using tables, and the PT count does compress, but only by ~ 4:1 so large proms are out.

A more crafted CPLD approach, is to start with a triangle counter that matches the 45' slopes of a sine wave, and then stretch the peaks/shoulders with a separate swallow counter.
This also uses all steps in a DAC.

Use separate software to calculate the size/placement of the stretch placements. This tends to work best with a fixed-count per Sine cycle, so to vary the Sine value, you need to vary the master clock.

What Frequencies, Step size, and sine distortions are you targeting ?

Another approach, if you want precise Audio sine from a MicroController, is to let the uC manage the Octave clocking, and use a Serial Flash to store fractional octave values.

Serial flash are cheap, and would link nicely to SPI DACs, and the CPLDs you have could manage clocking/modulus preloads & recirculate to a preloaded base offset.



List of 24 messages in thread
TopicAuthorDate
256bit x 8 proms      Jason Arkwright      05/15/12 04:44      
   What frequency Sine wave & Clock ?      Jim Granville      05/15/12 05:37      
      Thank you      Jason Arkwright      05/15/12 08:10      
         DDS (Direct Digital Synthesis)      Jim Granville      05/15/12 17:49      
         digital sine wave      Andy Peters      05/16/12 21:24      
            uC sine generator      Jason Arkwright      05/17/12 04:36      
               DMA      Aubrey Kagan      05/17/12 06:43      
               neither do I      Erik Malund      05/17/12 07:07      
                  ARN      Michael Karas      05/17/12 15:30      
                  'F120 Series      Michael Karas      05/17/12 15:58      
               Other solutions      Jim Granville      05/17/12 20:12      
               150nS access time is so long      Justin Fontes      05/17/12 22:13      
            is that realy the case?      Richard Erlacher      05/23/12 16:21      
   Of course my solution      Jez Smith      05/19/12 09:11      
      Hmmm.., nice but...      Jason Arkwright      05/20/12 12:29      
         Those are actually PALs not CPLDs      Jez Smith      05/20/12 12:44      
         ATF750CL for PT clocks      Jim Granville      05/20/12 16:38      
            ATF750      Jason Arkwright      05/21/12 09:21      
               ATF750C ?      Jim Granville      05/22/12 23:42      
                  Yes, Jim You are exactly right.      Jason Arkwright      05/26/12 12:49      
                     Can I suggest      Jez Smith      05/26/12 14:00      
                     ATDH1150USB      Jim Granville      05/26/12 19:45      
                        Update : ATDH1150VPC      Jim Granville      05/27/12 05:57      
                        Thanks JIM      Jason Arkwright      05/31/12 15:57      

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