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Chipcon modules CC1000PP

Discussion in 'Electronic Design' started by Sebasto, Aug 29, 2003.

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  1. Sebasto

    Sebasto Guest

    Hi

    Currently I'm designing RF link using CC1000PP module from Chipcon. I set up
    modules to Manchester data format and 19,2 kbps data rate. After calibration
    I send data from microcontroler to transmitter with preamble and header. On
    the receiver side I read data but in DCLK and DIO I have a lot of jitter.
    There is little jitter ( not much ) when data is constant 1 or 0 or when
    data is 0xAA, 0x55 etc. In data rate below 19,2 kbps I can read data
    correctly, but above 19,2 kbps jitter is so big that I can't correctly read
    data from the receiver.
    Could you tell me what causes jitter in DCLK and DIO signal ?

    Best Regards

    Sebasto

    sebastor(at)wp.pl
     
  2. Dana Raymond

    Dana Raymond Guest

    I have no experience with these devices, but have a suggestion... Could
    jitter at the transmitting end be a problem? Also, if the jitter increases
    as each individual bit is transmitted in time, then you may have a clock
    domain issue of some sort, or a source of 60Hz noise being injected or
    picked-up.

    Totally a stab in the dark.
    Dana Frank Raymond
     
  3. MarkyMark

    MarkyMark Guest

    Sebasto,

    There is a relatively obscure requirement to change the PLL loop bandwidth
    when using bit rates of 38400 and above. If your data is 19200baud,
    manchester encoded, then your bit rate is 38400.

    Register @0x42 defaults to 0x25 for rates up to 19200bps, you need to set
    this to 0x3f for your set up. This is not clear in the datasheet. The chip
    does a poor job of modulation for higher speeds when using the default,
    hence your RX jitter.

    Regards Mark
     
  4. Grog

    Grog Guest

    I was wondering if you were going to tell or not.... :)

    GtG
    "It's not a bug, It's an undocumented feature"
     
  5. MarkyMark

    MarkyMark Guest

    Yeah well sometimes you just gotta be the bigger person. Sebasto could of
    thrashed around for ages..... Luckily us west aussies are on top of things
    (or is that underneath things). It's all relative according to that German
    guy.

    Stay Lucky

    Mark
     
  6. Sebasto

    Sebasto Guest

    Hi

    Already traceiver workinkg preperly. I knew about TEST4 register, bad I made
    some mistake in one of procedures :|

    Regards

    Sebasto
     
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