[U-Boot-Users] I2C @ MPC8343

[Martin Krause]

Hi Andre,

Andre Schwarz wrote on Thursday, April 10, 2008 2:14 PM:
>> The number of address bytes a device needs is varying. Your could
>> look up the correct address length in the datasheet of your device,
>> or try it manually:
>> 
>> imd 50.0 0 10
>> imd 50.1 0 10
>> imd 50.2 0 10
>> 
>> One of this should work.
> 
> 
> no - only 0xff.
> Scope shows valid I2C transactions with correct data.

If you see the correct data on the bus with your scope and U-Boot 
nevertheless shows only 0xff, this seems like a bug in U-Boot to mee.
If you set the address lenght (.x spezifier) wrong, then the data
you see on the bus will also be wrong.

>> One reason for a hanging bus could be a lost clock pulse. This could
>> happen, if the low->high rise time of the bus signal is longer than
>> the clock pulse width. For testing you could try a lower bus clock
>> (10 kHz for example).
> 
> 
> rise time is  ~200ns.

This should definitely be fast enough (for 100 kHz)

Best Regards,
Martin Krause
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