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| CPLDs.... http://forum.6502.org/viewtopic.php?f=10&t=3261 |
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| Author: | banedon [ Tue Apr 14, 2015 5:13 pm ] |
| Post subject: | Re: CPLDs.... |
BTW you can erase a CPLD can't you? I know it sounds like a daft question, but so far cannot find a straight answer. I'm worried as I keep seeing comparrisons with PALs as opposed to GALs. That might be just that PALs came first, but... [edit] typo correction |
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| Author: | BigEd [ Tue Apr 14, 2015 6:02 pm ] |
| Post subject: | Re: CPLDs.... |
You can reprogram them, which is sort of the same thing: you just load a new design. Unlike EPROMs, there's no notion of erase or of partial programming. |
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| Author: | BigDumbDinosaur [ Tue Apr 14, 2015 7:18 pm ] |
| Post subject: | Re: CPLDs.... |
banedon wrote: BTW you can erase a CPLD can't you? I kniw it sounds like a daft question, but so far cannot find a straight answer. I'm worried as I keep seeing comparrisons with PALs as opposed to PALs. That might be just that PALs came first, but... As Ed noted, you just load new code into the CPLD. The software that does the loading automatically "erases" the previous code for you. Some CPLDs can only tolerate a limited number of erase/program cycles. For example, the ATF1504AS CPLD can be reprogrammed up to 10,000 times, but the Altera MAX7000 CPLD is only good for 100 programming cycles. Be sure to consult the data sheet for the device you are using. |
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| Author: | BigEd [ Tue Apr 14, 2015 7:20 pm ] |
| Post subject: | Re: CPLDs.... |
Hmm, 100 reprograms isn't so very many - well spotted. (Although, even for a hobbyist developing by trial and error, 100 mightn't be too big a problem. Especially if the parts are cheap.) |
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| Author: | BigDumbDinosaur [ Tue Apr 14, 2015 7:27 pm ] |
| Post subject: | Re: CPLDs.... |
BigEd wrote: Hmm, 100 reprograms isn't so very many - well spotted. (Although, even for a hobbyist developing by trial and error, 100 mightn't be too big a problem. Especially if the parts are cheap.) I'd expect that CPLD reprogramming wouldn't occur nearly as often as, say, reprogramming an EPROM, so 100 seems to be reasonable. Once the circuit logic is working as it should no further programming cycles would be needed unless some new functionality is to be added. |
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| Author: | banedon [ Tue Apr 14, 2015 8:14 pm ] |
| Post subject: | Re: CPLDs.... |
Thanks guys. I thought that this might be the case. |
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