Hi,
I'm polling an one-wire network that will contain more than 30 DS18B20
powered temp sensors along with other lcd and switches.
As suggested, I use the simultaneous to initiate conversion on all sensors
allowing me to do some other bus activities during conversion (750ms for
12bits).
Later, once conversion is known to be finished , I search for alarmed
devices. this is working ok perfectly.
I do this operation once every 10 seconds.
My question now:
Using this technique, I also expected to regularly read temp all my devices.
The temp information is already in the scratchpad from last simultaneous
request, however, reading temperature12 restart a whole conversion cycle.
It would be very usefull to have a way to read the scratchpad stored temp
explicitely.
Pascal
2009/4/28 Paul Alfille <[email protected]>
> You can use the "simultaneous" conversion -- which can test a large pool of
> temperature chips simultaneously. Only with external power. of course.
>
> Paul Alfille
>
>
> On Mon, Apr 27, 2009 at 5:25 PM, Michael Markstaller <[email protected]>wrote:
>
>> Alarming with the DS18B20 on Temphigh/low works fine with owfs - but I
>> guess thats what Jim means -
>> only after a conversion was once (manually) initiated. Also unfortunately
>> regardless wether they're powered with Vdd or not. Thats IMHO a flaw with
>> the chip, surely not owfs, but it would only make deeper sense if the DS18xx
>> would do this by themselves and then alarm.
>> So one has to initiate reading the temp anyway, which is the most
>> time-consuming part and can use the measured temp directly, alarming is in
>> this case, at least in this case for me quite useless ;)
>> But now, its still a minor problem 'cause polling the temps is also fine
>> within a few seconds..
>>
>> Michael
>>
>
>
>
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