Re: [Gumstix-users] overo I2C pull-up resistors

[Martin S. <ma...@rp...>]

Did you check the configuration of these I2C lines for internal pull-up resistors that might be enabled with your configuration?

-Martin

On 03/28/2013 03:02 PM, the suicidal eggroll wrote:
> So I found and removed a pair of 1.5k pull up resistors for the I2C-3 lines
> on the Tobi, which helped.  It now takes 3.7mA to drive the lines low
> instead of 4.7mA.  The MSP430 is able to get the line lower than before, low
> enough now for the gumstix to register the clock stretch and stop pumping
> out data, but not low enough for it to register the ack.
>
> The weird thing is that with these resistors on the Tobi gone, I'm measuring
> no significant resistance between the I2C lines and 1.8v, yet once the
> gumstix is powered up the lines are being pulled high so hard that it takes
> 3.7mA to drive them to 0 (the equivalent of 490 ohm pull ups).
>
> I really wish Gumstix would release the schematics of their COMs so I could
> see what's going on here.
>
>
>
> --
> View this message in context: http://gumstix.8.n6.nabble.com/overo-I2C-pull-up-resistors-tp4967078p4967079.html
> Sent from the Gumstix mailing list archive at Nabble.com.
>
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