That's a tough question about which is safer or more reliable. I guess it depends on the cross-section of devices being probed. I've had a mobo a few years ago which would lock up the SMBus (not even the reset button fixed the condition) if the device at 0x69 was sent a quick-write. It turned out to be a clocking chip which hung the bus because it was anticipating more data following the quick-write and didn't time out. Some simple devices only respond to the quick-commands and switch things on or off depending on it if got a quick-read or write. In that case, doing either quick command would cause a potential state-change in the device instead of doing a non-intrusive probe. Oh, lastly, I think all I2C/SMBus transations start with a quick-type transaction. So, if I have my head screwed on straight, it is impossible to not detect a chip with a quick-read which supports, say, a I2C Block-read. Phil On Wed, Mar 06, 2002 at 06:16:55PM -0600, leo.duran at amd.com wrote: > Phil, > > Thanks for the reply. > Your observations are in line with what I'm seeing. > > I have a DIMM at 0x50 that's somehow responds to "QuickWrite" > at 0x30. But if do a "QuickRead", only the (real) device at > 0x50 responds. It's doing a "QuickRead" an OK detection mechanism? > It seems most people prefer "QuickWrite" for device detection. > > Thanks, > Leo. > > -----Original Message----- > From: phil at netroedge.com [mailto:phil at netroedge.com] > Sent: Wednesday, March 06, 2002 5:59 PM > To: Duran, Leo; sensors at Stimpy.netroedge.com > Subject: Re: I2C device identification > > > > If you see a device at, say, 0x31 and 0x51 which both seem to be > eeproms, then they are most likely the same device responding to > either address. Don't count on most eeproms to show up twice like > this, though. It is possible to have devices in the 0x30-0x3f and > 0x50-0x5f be independant, unqiue devices. It appears to be rare (at > least on motherboards). > > I hope this helps. > > > Phil > > On Wed, Mar 06, 2002 at 10:44:15AM -0600, leo.duran at amd.com wrote: > > Hello, > > > > In the "I2C Tools Page": http://www2.lm-sensors.nu/~lm78/i2ctools.html > > there is chart listing general devices addresses. > > > > The range 0x30 thru 0x37 is listed as "eeprom shadow", whereas the range > > 0x50 thru 0x57 is listed as "eeprom". Does this mean that the same (eeprom) > > device will respond to both addresses? Or are these two distint devices? > > > > Thanks for the clarification, > > Leo Duran. > > > > -- > Philip Edelbrock -- IS Manager -- Edge Design, Corvallis, OR > phil at netroedge.com -- http://www.netroedge.com/~phil > PGP F16: 01 D2 FD 01 B5 46 F4 F0 3A 8B 9D 7E 14 7F FB 7A -- Philip Edelbrock -- IS Manager -- Edge Design, Corvallis, OR phil at netroedge.com -- http://www.netroedge.com/~phil PGP F16: 01 D2 FD 01 B5 46 F4 F0 3A 8B 9D 7E 14 7F FB 7A
