[U-Boot-Users] PQ2FADS i2c -- no SCL

Scott McNutt ScottM at Orbacom.com
Wed Jan 21 23:17:21 CET 2004

>     Scott> Using u-boot 1.0.1 with PQ2FADS ... we're not seeing SCL
>     Scott> while executing i2c commands.  Port D settings are correct,
>     Scott> copper is good.
>     Scott> Has anyone seen a similar problem? Anyone successful?
> It used to work on MPC8260ADS and MPC8266ADS. On PQ2FADS, I2C is
> connected to nothing so it was not tested. It's expected to 
> be the same as on older boards.

I agree :-)

> I assume you use the expansion connector to add I2C
> hardware.


> I'd check first of all that the configuration
> (S/W and H/W)is the same as on older boards. Specifically,
> your add-on H/W must take care of I2C bus requirements.

SDA and SCL are pulled up as required. We got it working
by disabling open-drain output for SCL (PD14 ODR = 0).
Perhaps the transceiver (U18) has gone soft on us.

So ... this work-around is ok only for single master.

Yuli, if you ever get around to trying this on your
board, I'd be interested to know if you observe the
same behavior. Perhaps just scope SCL with a pull up
without a slave device.

Thanks for your suggestions.


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