Ulrich As in the difference between the DS620 (10, 11, 12, or 13 bit directly with no additional calculation) and the DS1620 (9 bits + 3bits extension via the procedure in the datasheet)?
The original post did state that the sensor was a DS1620. Mark also stated in a later post that he had replaced the chip a new DS1620 with no effect on the resolution of the reported temperature. Bruce Ulrich Bangert wrote: > Gents, > > has anyone checked which DALLAS part is REALLY inside the box? > > I put forward this question because DALLAS has parts in their portfolio > that sell as "genuine" 12-bit resolution ones and other ones that sell > as 9-bit resolution ones where additional 3 bits of resolution can be > used by some "tricks" The software for these two types is NOT the same. > > Best regards > Ulrich Bnagert > > >> -----Ursprungliche Nachricht----- >> Von: [email protected] >> [mailto:[email protected]] Im Auftrag von [email protected] >> Gesendet: Donnerstag, 5. Februar 2009 11:15 >> An: [email protected] >> Betreff: Re: [time-nuts] Tbolt temperature sensor >> >> >> >> In a message dated 05/02/2009 06:25:52 GMT Standard Time, >> [email protected] >> writes: >> >> Actually, what is apparently going on with the newer >> Thunderbolts is worse >> than that. The reported temperature seems to only end in >> 0.25C or 0.75C, so >> it has an effective 0.5C resolution. The basic DS1620 >> resolution is 9 >> bits, but the Tbolt firmware reduces that to 8 bits since >> the first step in the >> high res temp algorithm is to mask off the lower bit. >> Whatever is going on >> they are not getting the extra resolution that they think >> they are, and in >> fact they are reducing the basic resolution of the chip. >> >> The firmware does seem do do some filtering on those values >> since whenever >> the reading steps you can see some smoothing going on. A >> lot of times the >> temperature value oscillatates around the step point. The >> filter apparently >> does not have any hysteresis. >> >> The older Thunderbolts produced a nice smooth curve. The high res >> temperature reading (Bruce says is 12 bit/0.0625C) coupled >> with the firmware filtering >> gave temperature curves with microdegree scale resolution. >> The newer ones >> clunk around with effectively 0.5C resolution. >> >> >> >> -------------------------------- >> But have you actually established this has anything >> whatsoever to do with >> the oscillator conditioning and, if not, what effects are you >> suggesting it has >> on the conditioned output? >> >> Isn't it likely that a temperature sensor adjacent to the >> RS232 connector is >> just going to monitor unit temperature for environmental >> purposes, perhaps, >> for example, to give the option for flagging up an >> overheating situation, in >> which case surely 0.5C resolution is more than adequate and >> the "clunkiness" >> isn't really an issue? >> >> I agree it's always nice to know what's happening, and why, >> but I suspect >> the performance of this sensor has no relevance to the >> oscillator performance >> itself. >> >> regards >> >> Nigel >> GM8PZR >> >> regards >> >> Nigel >> GM8PZR >> _______________________________________________ >> _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
