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  • Author Author: packetgeek
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Si4707 effort on hold

packetgeek

I'm putting the I2C coding effort for the Si4707 chip on hold.  The basic initialization code (same as for the Si4703 breakout board) does not work with the Sparkfun board.  Cause seems to be double-use of pull-up resistors (one set on the Pi, another on the Sparkfun board) that were added by Sparkfun.  Because of this, I don't believe that the I2C interface will work with the Pi without modifying the board.

 

Supporting this are the following:

 

Will revisit the chip when I'm learning how to work with the SPI interface, or work with a computer that doesn't add its own set of pull-up resisistors.  Maybe a Cubieboard or the XMOS controller.  Will need to dig.  In the mean time, this allows me to move on to the AS3935 lightning sensor and the Si4735 eval kit.

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  • In software you can change whether it is a pull up or up down:

     

    GPIO.setup(23, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)
    GPIO.setup(24, GPIO.IN, pull_up_down=GPIO.PUD_UP)

    Do not know if this helps...

    Clem

  • in reply to clem57

    Thanks for the suggestion but (sorry) it didn't work.  I've hit a wall with this one and can only assume that it won't work with the Pi, based on:

     

    - having two Si47xx based boards from Sparkfun

    - Silicon Labs' documentation indicating that the same technique should drive them into I2C mode
    - various docs indicating that the Sparkfun board and the Pi each have a set of resistors

     

    The painful part is that, if the above is true, the Si4703 shouldn't have worked (but it has a similar set of resistors and does work).  Maybe I've missed something.  It's doubtful as other user's code also does not work.  The board refuses to show up on the I2C bus.  It could be that I've damaged the board somehow.

     

    I think the best course is for me to learn how to use the SPI interface (on the Si4703) and come back to the Si4707 later.  I'll also be on the look-out for a non-Sparkfun version of the breakout board.

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  • in reply to clem57

    Thanks for the suggestion but (sorry) it didn't work.  I've hit a wall with this one and can only assume that it won't work with the Pi, based on:

     

    - having two Si47xx based boards from Sparkfun

    - Silicon Labs' documentation indicating that the same technique should drive them into I2C mode
    - various docs indicating that the Sparkfun board and the Pi each have a set of resistors

     

    The painful part is that, if the above is true, the Si4703 shouldn't have worked (but it has a similar set of resistors and does work).  Maybe I've missed something.  It's doubtful as other user's code also does not work.  The board refuses to show up on the I2C bus.  It could be that I've damaged the board somehow.

     

    I think the best course is for me to learn how to use the SPI interface (on the Si4703) and come back to the Si4707 later.  I'll also be on the look-out for a non-Sparkfun version of the breakout board.

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