| ??? 05/20/12 22:38 Read: times |
#187451 - ATF750CL for PT clocks Responding to: ???'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. |
| Topic | Author | Date |
| 256bit x 8 proms | 01/01/70 00:00 | |
| What frequency Sine wave & Clock ? | 01/01/70 00:00 | |
| Thank you | 01/01/70 00:00 | |
| DDS (Direct Digital Synthesis) | 01/01/70 00:00 | |
| digital sine wave | 01/01/70 00:00 | |
| uC sine generator | 01/01/70 00:00 | |
| DMA | 01/01/70 00:00 | |
| neither do I | 01/01/70 00:00 | |
| ARN | 01/01/70 00:00 | |
| 'F120 Series | 01/01/70 00:00 | |
| Other solutions | 01/01/70 00:00 | |
| 150nS access time is so long | 01/01/70 00:00 | |
| is that realy the case? | 01/01/70 00:00 | |
| Of course my solution | 01/01/70 00:00 | |
| Hmmm.., nice but... | 01/01/70 00:00 | |
| Those are actually PALs not CPLDs | 01/01/70 00:00 | |
| ATF750CL for PT clocks | 01/01/70 00:00 | |
| ATF750 | 01/01/70 00:00 | |
| ATF750C ? | 01/01/70 00:00 | |
| Yes, Jim You are exactly right. | 01/01/70 00:00 | |
| Can I suggest | 01/01/70 00:00 | |
| ATDH1150USB | 01/01/70 00:00 | |
| Update : ATDH1150VPC | 01/01/70 00:00 | |
Thanks JIM | 01/01/70 00:00 |