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Digital Wire — Parallax Forums

Digital Wire

steprogsteprog Posts: 227
edited 2009-10-06 02:40 in Propeller 1
Hello Guys,
Im looking a high speed A/D to DAC through a prop using hopefully a serial bus on each side to minimize pins.· I need to create a digital wire as a first step.· After that put integraters and other stuff in for making a control loop.· Since I would like to drive each loop with one cog.· It would be nice to use a serial bus to get data in and data out so I can put several of these loops in one prop.· Im looking for 1Mhz performance.· Any Ideals?
Thanks in advance,
Greg

Comments

  • kwinnkwinn Posts: 8,697
    edited 2009-10-05 15:04
    steprog, when you say 1Mhz performance do you mean 1M samles/sec in from ADC and 1M samples/sec out to DAC per cog?

    Since a cog at 80Mhz can only execute 20 instructions per uSec pumping 1M samples/sec through using a serial protocol would seem to be just about impossible. It would be difficult even using parallel ADC/DAC's, and there would certainly not be any time for calculations.
  • steprogsteprog Posts: 227
    edited 2009-10-05 16:28
    Perhaps your right. I didn't think it through last night. Im looking for the fastest deal out there.
  • steprogsteprog Posts: 227
    edited 2009-10-05 20:38
    I was thinking that the SPI can move pretty quick. Say that it takes in one sample after 10 clks. then perhaps 100ks/sec maybe possible. I have often in the past checked out digital control loops by just creating a digital wire. Analog in digitized analog out.
  • Cluso99Cluso99 Posts: 18,069
    edited 2009-10-05 22:55
    Beau has proven 1MBs serial transfer. Obviously you still need to process this, but then again you do have multiple cogs for this.

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  • steprogsteprog Posts: 227
    edited 2009-10-05 23:37
    Im sorry i never heard of Beau. I've been around awhile but must not be keeping in touch. Can you enlighten me. Are there ad dacs that support this?
    Thanks,
    Greg
  • HannoHanno Posts: 1,130
    edited 2009-10-06 00:34
    Just a short PropScope teaser, since you're talking about ADC and DAC's [noparse]:)[/noparse]
    I'm using 5 cogs to CONTINUOUSLY input 32bits of data coming from 2 ADC's and LSA probes at 25Msps in the PropScope- WHILE looking for any type of complex trigger.
    I'm using a video generator to output arbitrary 8bit waveforms at 25Msps. Coming soon!

    If you can afford the pins and need the speed, I would input data in parallel from an ADC like ADC08100 and output in parallel using a resistor network...
    Hanno

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  • steprogsteprog Posts: 227
    edited 2009-10-06 02:40
    Hanno,
    Thats pretty slick. The video generator 8 bits would work fine. Is this something you are coming up with now?
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