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ATmega169 Puzzle

Discussion in 'Embedded' started by Joel, Mar 21, 2008.

  1. Joel

    Joel Guest

    Well a few days ago I was having trouble setting up a simple spi interface
    Whenever I would try to lower the chip select lines of my devices the 16
    would try it and then give up and reset itself.

    I finally figured out that the problem was the pin I was trying to use.
    was using PINB0 and PINB4 as chip select lines. B4 was the one giving m
    trouble so I switched it to B5 and the problem was solved. Now I'
    noticing that PINB6 does the same thing.

    What is going on here???
     
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  2. Arlet Ottens

    Arlet Ottens Guest

    Joel wrote:
    > Well a few days ago I was having trouble setting up a simple spi interface.
    > Whenever I would try to lower the chip select lines of my devices the 169
    > would try it and then give up and reset itself.
    >
    > I finally figured out that the problem was the pin I was trying to use. I
    > was using PINB0 and PINB4 as chip select lines. B4 was the one giving me
    > trouble so I switched it to B5 and the problem was solved. Now I'm
    > noticing that PINB6 does the same thing.
    >
    > What is going on here???


    Maybe you have interrupts enabled (by accident) on those pins, and no
    valid handler ?
     
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  3. larwe

    larwe Guest


    >  Whenever I would try to lower the chip select lines of my devices the 169
    > would try it and then give up and reset itself.


    Single-step; there is no reason why you shouldn't be able to use any
    GPIO as your SPI _SS. Also check that your circuit is not wired in
    some funky way whereby asserting _SS was shorting out the power
    supply.
     
  4. Joerg

    Joerg Guest

    larwe wrote:
    >> Whenever I would try to lower the chip select lines of my devices the 169
    >> would try it and then give up and reset itself.

    >
    > Single-step; there is no reason why you shouldn't be able to use any
    > GPIO as your SPI _SS. Also check that your circuit is not wired in
    > some funky way whereby asserting _SS was shorting out the power
    > supply.



    This may be the perfect time to leave the embedded/digital world for a
    minute, hang a scope on it and take a look.

    --
    Regards, Joerg

    http://www.analogconsultants.com/
     
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