Hi Sebastian, Did the modified driver solved your problem? Becous if it does, I would send this to a friend of mine who can commit to tinyos-main, and hopefully this will be part of tinyos 2.1.2.
Andris On Fri, Dec 9, 2011 at 6:58 PM, András Bíró <bband...@gmail.com> wrote: > Hi Sebastian, > > On Fri, Dec 9, 2011 at 2:30 PM, Sebastian Dölker > <sebastian.doel...@hs-karlsruhe.de> wrote: >> Hi Andris, >> >> Yesterday I continued with my i2c problems and discovered the following: >> >> The debug values: >> 20:03:44 "cmd" 0x00 0x00 >> 20:03:44 "ir read done.." >> 20:03:44 "init" 255 3 >> 20:03:44 "cmd" 0x04 0x01 >> 20:03:44 "cmd" 0x25 0x01 >> 20:03:44 "int" 0x08 0x01 >> 20:03:44 "cmd" 0x45 0xb5 >> 20:03:44 "int" 0x40 0xb5 >> 20:03:44 "cmd" 0x45 0xb5 >> 20:03:44 "int" 0x00 0x6a <- bus error >> 20:03:44 "cmd" 0x05 0x6a >> 20:03:45 "*start*" >> 20:03:46 "*start*" >> 20:03:46 "bb read done.." >> 20:03:46 "***start***" >> 20:03:46 "cmd" 0x04 0x6a >> 20:03:46 "*error*" <- error means EBUSY is returned.. >> 20:03:47 "***start***" >> 20:03:47 "cmd" 0x14 0x6a >> 20:03:47 "*error*" >> 20:03:47 "bb read done.." >> 20:03:48 "***start***" >> 20:03:48 "cmd" 0x14 0x6a >> 20:03:48 "*error*" >> > > Thanks, it's much more easier to fix with this help. > >> So the i2c-status is 0x00. >> According to the atmel128 datasheet page 224 this means bus error. >> To recover one should set TWSTO flag and clear TWINT („by writing a logic >> one to it“?!) > > Yes, the TWINT flags seems a bit illogical, but that's how you can > clear it. This translates to send a stop condition (TWSTO), and clear > the interrupt flag. > >> I didn’t find this procedure in the device driver sources. Is the bus error >> state handled in the driver? > > You're right, it doesn't handle it. Actually I don't like the > interrupt handler (I2C.commandComplete) at all, since it doesn't care > with the TWSR, it persumes that with its own internal state variable. > However, when I fixed some of the bugs in this, I wanted to change as > little as possible, becouse it's an old component, and some users may > count on this not quite good solution. > >> I tried to add this procedure but I wasn’t successful.. >> Must this be added in the driver? >> Have you an idea where? > > I attached the modified dirver, but I just tested it with a working > i2c sensor. It should do the recovery procedure, disable the i2c > interrupt, and return with FAIL. > >> >> One more, in the attachment I added a picture of the sequence while the >> error occurs. >> Channel 1 is i2c-clock, channel 2 i2c-data. At the beginning the i2c sensors >> are read out successfully. >> Then a sensor pulls clock low for ca. 2.3 seconds. Probably because of that >> the bus error occurs. > > The atmega1281 datasheet mention that bus error only occurs when an > illegal start/stop condition happens. It would be more intresting to > see the last part of the failed communication in detail, to check for > this. Although if that's the case, we couldn't do much more, a slave > device should never send start/stop, so this is a bug in your sensor. > Handling bus error interrupt should fix it, but it's just a > workaround. > > Andris > >> >> Thanks in advance! >> Best regards >> Sebastian _______________________________________________ Tinyos-help mailing list Tinyos-help@millennium.berkeley.edu https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
