[lm-sensors] i2cdetect running slow but not "bus inactive" slow, not sure why?
guenter.roeck at ericsson.com
Fri Dec 16 17:29:47 CET 2011
On Fri, 2011-12-16 at 10:33 -0500, Wayne Tams wrote:
> i2cdetect is behaving in a fashion that I have not seen before and I
> just would like to know if anyone has a suggestion on what it is
> telling me.
> Normally i2cdetect returns in <1s, if the bus were inactive it would
> take closer to 20s. However I'm finding that the scanning is taken a
> round 5s and the addresses returned appear random, except for one.
> Obviously there must be a fault in my hardware, but I just wanted to
> make sure that was/wasn't a common explanation for this behaviour
> before I go debugging up the wrong tree.
I typically see this kind of problem if there is something wrong on the
i2c bus, for example if a signal is pulled high or low. I have also seen
it after I managed to physically "destroy" an I2C controller by applying
a reversed voltage to the i2c signal pins.
If you have a logic analyzer or a scope, you might want to connect it to
the clock and data lines to see what is happening on the bus.
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