Actually I don't see anything but a straight line on the Oscope trace, but that could just be me...
The slave address needs to be shifted up one bit in the first byte sent, because the LSB (bit 8) is the rd/bar-wr bit. It's not clear to me if that is what you are doing (because I can't see anything in the picture). Perhaps that is what you mean by "0x32 followed by a 0 and a 1 (no ack)"... It is also not entirely clear from the spec sheet if the 0x32 slave address is before or after shifting, have you tried both? I'm not familiar with the telos/MSP in this respect. You're sure that there is no conflict on the I2C bus, and also that you have the pull- up resistors in place? Looks like a nice compass chip. You doing robotics? MS Tommaso Montisci wrote: > I'm using the I2C part of the MSP430 datasheet and it seems very clear: > http://focus.ti.com/lit/ug/slau049f/slau049f.pdf > From my oscilloscope (scl , sda) the synchronization between clock and > data seems ok, has you can see in the picture attached. > There should be an ack there on the 9th bit? > The slave address should be ok, 0x32, the default address standing at > the datasheet http://www.magneticsensors.com/datasheets/HMC6343.pdf > > From the picture we can recognize the bits and indeed it is 0x32 > followed by a 0 and a 1 (no ack). > > I do not know what to do... > > thanks, > Tommaso > > > 2009/8/24 Michael Schippling <[email protected] <mailto:[email protected]>> > > This is the I2C spec for the chip I was fighting: > http://www.nxp.com/acrobat_download/usermanuals/UM10204_3.pdf > It has a (to me) useful description of the spec and clock/data sequence. > Careful comparison to your observations might turn something up. > Pay attention to the relationship between clock and data...IIRC the > data must be stable the entire time the clock is active (high or low, > I don't remember for sure...) > > Are you sure you are sending the right slave address? If the target > doesn't agree it won't respond. > > Is your TOS MSP I2C implemented in hardware or software? > > MS > > > Tommaso Montisci wrote: > > Hi Michael, thanks for your answer. > > I try to explain you my problem: > I'm able to send the START condition and the slave address, but > I receive no ACK from my sensor(HMC6343 digital-compass). I know > that I have sent the right-byte through the Oscilloscope. > Without the acknowledgment it seems that I'm not able to sent > further data to my device (is it true that I need the ack before > sending data?). > > Have you any suggestions? > > best, > Tommaso. > > > > 2009/8/23 Michael Schippling <[email protected] > <mailto:[email protected]> <mailto:[email protected] > <mailto:[email protected]>>> > > > I discovered a "lapse of implementation" in the T1 atmega I2C > implementation, which is BTW entirely done in bit-banging > software. > I don't use or have access to a T2 tree and haven't looked at the > MSP implementation, but I might be able to help if you describe > your problem. > > My problem was when reading multi-byte data from an I2C device. > According to the spec the slave can request a "wait-state" > between > bytes. The TOS code was ignoring this and getting out of bit > sync. > > MS > > Tommaso Montisci wrote: > > Hi all, > > I'm working to write TinyOS 2.x drivers for a 3-axiss digital > compass(HMC6343). > This sensor communicates via a two-wire I2C bus system as a > slave divice with a microprocessor MSP430. > I would like to know if someone just working in similar > context > couse I'm in trouble to recive the ack from the compass. > > Thanks, > > Tommaso Montisci. > > > > > ------------------------------------------------------------------------ > > _______________________________________________ > Tinyos-help mailing list > [email protected] > <mailto:[email protected]> > <mailto:[email protected] > <mailto:[email protected]>> > > > > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > > > > > ------------------------------------------------------------------------ > _______________________________________________ Tinyos-help mailing list [email protected] https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
