i2c pullups

Questions on control of serial busses
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YahooArchive
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Joined: Fri Oct 19, 2012 5:11 am

i2c pullups

Post by YahooArchive » Thu Oct 25, 2012 9:43 pm

>are there IO lines that are specifically designated to I2C on the
Armmite (rev2),
> i.e lines that are pulled up to +5v?

Any of the IOs can be used to drive an I2C device, but none have
pullups. The software library will only drive an I2C line low, and
for high it will be tri-stated, so it requires an external resistor
pullup.

As for resistor values, any value from 1.8K to 4.7K would be
appropriate. If you have a lot of devices or very long cable runs,
then use a lower value.



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