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Re: [AQRP] Si570 Controller update

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  • John H. Fisher
    Bill, this is excellent feedback and completely jives with my experience, including cycling power :-) Thank you very much for verifying that I m not going nuts
    Message 1 of 3 , Feb 19, 2008
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      Bill, this is excellent feedback and completely jives with my
      experience, including cycling power :-) Thank you very much for
      verifying that I'm not going nuts :-) It's been suggested by Ross that
      we approach Silicon Labs about this apparent hardware problem. I bet the
      non-CMOS versions sing like a canary at their specified frequencies (
      wishful thinking on my part ). But the fact that both you and I have
      experienced the exact same phenomenon is significant :-) It makes you
      wonder if any body else has tried their CMOS Si570 above 80MHz. I know
      what is happening is the first few registers get loaded then the slave
      Si570 stops ACK 'ing the Data so it hangs with an incomplete RFREQ. But
      it still runs and changes the oscillator even with the frozen DCO. I
      need to remember to try reseting the chip before loading registers as a
      possible fix. Thanks again for your feedback. If you hear of anyone
      running their Si570 above 80 MHz, please let us know. Also, Jim, the
      Softrock divides the clock by four so an 80MHz oscillator will only tune
      to 20 MHz. Not bad as you say but we need 120 MHz.

      Bill Tracey wrote:
      >
      > John - you and I should compare notes on this a bit. I've got one of
      > the Si570's hooked up to an HPSDR Ozy board and am programming it via
      > its I2C over USB and see the thing go flakey above 90 MHz -- at some
      > point up near 90 Mhz the little 570 goes off to la la land and will
      > not talk to me unitl I cycle the power on it. It's not that I've
      > lost the I2C bus or the microcontroller on the bus since I can talk
      > to the other I2C dev's on the bus when the 570's gone away.
      >
      > Cheers,
      >
      > Bill (kd5tfd)
      >
      > At 09:47 PM 2/18/2008, John H. Fisher wrote:
      > >Ah, the silence is deafening :-) Yes, I hit a wrinkle which has cost me
      > >a day or so. I wrote a test program which tells the Si570 to output
      > >10MHz for 4 seconds, then 20MHz for 4 seconds, then 30MHz, 40MHz, 50MHz,
      > >60MHz, 70MHz, and 80 MHz and start over at 10MHz. This all works quite
      > >well. But when I program it to 90MHz or above, it loads one or two
      > >registers then it refuses to Acknowledge the data. So it sits there
      > >waiting for an ACK forever. This is also true for 120MHz. I suspect the
      > >CMOS version of the Si570 is limited to less than the published 160 MHz.
      > >So we might try the other high speed versions. For now I will
      > >investigate the failed ACK. It seems to accept r7 and r8 but not the
      > >RFREQ value. So 90 MHz comes out 101MHz. And 120MHz comes out 115MHz
      > >because it never finishes loading the RFREQ values. The Stuck ACK locks
      > >it up waiting. But it ACK's everything below 90MHz parameters. Maybe the
      > >Si570 is rejecting the parameters above 80MHz for some reason. Anyway
      > >that's a pretty impressive range for a VFO 10 to 80 MHz. Hence the
      > >silence :-)
      > >
      > >--
      > > Regards,
      > > John
      > >
      > >=========================================================
      > >email: k5jhf@... <mailto:k5jhf%40sbcglobal.net>
      > >photos: http://www.flickr.com/photos/k5jhf/sets/
      > <http://www.flickr.com/photos/k5jhf/sets/>
      > >videos: http://www.youtube.com/profile?user=k5jhf
      > <http://www.youtube.com/profile?user=k5jhf>
      > >files: http://briefcase.yahoo.com/k5jhf@...
      > <http://briefcase.yahoo.com/k5jhf@...>
      > >web page: http://www.geocities.com/k5jhf@...
      > <http://www.geocities.com/k5jhf@...>
      > >call sign: K5JHF
      > >=========================================================
      > >
      > >
      > >
      > >Via the Austin QRP Club list
      > >Yahoo! Groups Links
      > >
      > >
      > >
      >
      >

      --
      Regards,
      John

      =========================================================
      email: k5jhf@...
      photos: http://www.flickr.com/photos/k5jhf/sets/
      videos: http://www.youtube.com/profile?user=k5jhf
      files: http://briefcase.yahoo.com/k5jhf@...
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      call sign: K5JHF
      =========================================================
    • John H. Fisher
      At first blush, it looks like we might have some sort of restart condition. Rather than just waiting for the ACK, I might just have to believe it is a NAK, and
      Message 2 of 3 , Feb 20, 2008
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        At first blush, it looks like we might have some sort of restart
        condition. Rather than just waiting for the ACK, I might just have to
        believe it is a NAK, and try resending the byte. This is my next move
        toward being more robust as Mike says :-) Thanks for everyones suggestions

        George Heron wrote:
        >
        > Wonder if the device is going into UHF oscillation,
        > thus effectively locking it up.
        >
        > Have you guys noticed a notable increase in the supply
        > current as the threshold is crossed going to
        > flakiness?
        >
        > Have you taken any specific cautions regarding the
        > layout of the ground plane (or even just the
        > power/ground wiring and rail bypassing)?
        >
        > ~George N2APB
        >
        > --- Bill Tracey <kd5tfd@... <mailto:kd5tfd%40arrl.net>> wrote:
        >
        > > It is. I just got some of the LVDS versions a day
        > > or two back but
        > > have not gotten round to playing with them as yet.
        > >
        > > Regards,
        > >
        > > Bill (kd5tfd)
        > >
        > >
        > > At 05:52 PM 2/19/2008, Kees & Sandy wrote:
        > > >Bill, is that the CMOS version ?
        > > >73 Kees K5BCQ
        > > >
        > > >-- Bill Tracey <kd5tfd@... <mailto:kd5tfd%40arrl.net>> wrote:
        > > >
        > > >John - you and I should compare notes on this a
        > > bit. I've got one of
        > > >the Si570's hooked up to an HPSDR Ozy board and am
        > > programming it via
        > > >its I2C over USB and see the thing go flakey above
        > > 90 MHz -- at some
        > > >point up near 90 Mhz the little 570 goes off to la
        > > la land and will
        > > >not talk to me unitl I cycle the power on it. It's
        > > not that I've
        > > >lost the I2C bus or the microcontroller on the bus
        > > since I can talk
        > > >to the other I2C dev's on the bus when the 570's
        > > gone away.
        > > >
        > > >Cheers,
        > > >
        > > >Bill (kd5tfd)
        > >
        > >
        > >
        >
        >

        --
        Regards,
        John

        =========================================================
        email: k5jhf@...
        photos: http://www.flickr.com/photos/k5jhf/sets/
        videos: http://www.youtube.com/profile?user=k5jhf
        files: http://briefcase.yahoo.com/k5jhf@...
        web page: http://www.geocities.com/k5jhf@...
        call sign: K5JHF
        =========================================================
      • John H. Fisher
        Excellent results, Kees, thanks for the report. No doubt your tight layout and decoupling did the trick :-)
        Message 3 of 3 , Aug 4, 2008
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          Excellent results, Kees, thanks for the report. No doubt your tight
          layout and decoupling did the trick :-)

          Kees & Sandy wrote:
          >
          > I built up the first production board and all appears well. The SiLabs
          > spec for the CMOS part is 10Mhz to 160Mhz. I can easily run the part
          > down to 4Mhz and well above 160Mhz. Above 180Mhz the output level
          > starts to drop but I still see a nice waveform up to 290Mhz but the
          > amplitude has fallen to 500mV p-p. It does not take too much board
          > capacitance to bleed off frequencies like that. There does not appear
          > to be any "unwanted interaction" between the Microcontroller and Si570
          > part although I don't know exactly what that problem was. There is a
          > lot of grounding and shielding on that little board and very short
          > leads. I'm also running off 2.9V bateries from Austin Summerfest demos
          > and may be able to push it further on 3.3V from the regulator.
          > Man, that Si570 is one cool part ! I also want to try one of the LVDS
          > parts and I have one on the desk ......somewhere. Looked, but all I
          > could find were my 4 CMOS parts.
          > Now to get some additional parts together. I do not have the
          > additional Si570 parts yet for the kits.
          > 73 Kees K5BCQ
          >
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