Wolfgang,
I have indeed a LM75 on this bus - but it's not adressed. The same I2C bus works fine on linux-2.6.25 including LM75 and EEPROM.
The oszi shows complete transactions with valid data. I think it is as software issue.
Thanks, Andre
w.wegner@astro-kom.de schrieb:
Hi,
On 10 Apr 2008 at 13:08, Martin Krause wrote:
After some tries (i2c md ..) the bus hangs and no more transactions can be seen on the bus.
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).
sorry if I did not follow the discussion up to here. As I stumbled over it yesterday, I just want to give another example how to hang a bus.
There are devices (namely LM75) that claim to be I2C devices but do not care about I2C specification. In case of LM75, a read must always be 16 bit (2 bytes), in case of reading only 1 byte the device does not interpret the missing ACK correctly and, in case the last byte read is '0', it will block the bus until some more (worst case 8) SCL pulses follow.
Maybe something like this could also happen in your case?
Regards, Wolfgang
MATRIX VISION GmbH, Talstraße 16, DE-71570 Oppenweiler - Registergericht: Amtsgericht Stuttgart, HRB 271090 Geschäftsführer: Gerhard Thullner, Werner Armingeon, Uwe Furtner