Am 21.08.2016 um 13:25 schrieb Roland Franke:
>
>> .../latesttemp first reads data from the scratchpad, then looks
>> into data[4] to decide which resolution the data in data[0] and
>> data[1] have.
>
> Did by the first startup (When never something was read from am
> sensor with different resulution) read in the value für the highest
> resolution (First read 12 bit and only when selected sometime the
> lower one the lower for the next time) or is first read in the 9bit
> resolution and only when selected sometimes the higher one the next
> times also the higher one?
>
Each sensor has its own scratchpad. When you read latesttemp on a sensor
on which there was never a conversion triggered, you get 85°C, the power
on default value.
As soon you trigger a simultaneous conversion, the resolution used is
determined for the configuration byte which was previously stored inside
the sensor. The power-up default value is taken from the EEPROM
configuration of the sensor. Factory default is 0x7f, which means 12 bit
resolution. You can change that factory setting (no way to do that with
owfs yet.)
As soon you trigger a single conversion on a sensor, the resolution is
changed to the one you requested. Note that .../temperature is an alias
for .../temperature12 on all chips but the DS18S20. It stays that way
for that single sensor until it power-cycles or the EEPROM contents is
recalled. You can do the latter by reading the .../templow or
.../temphigh nodes.
Kind regards
Jan
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