RE: Dallas temp sensors

["Paul Gordon" <paul_gordon@xxxxxxx>]

>
>The pins on the Dallas part are Ground -- Data -- Vdd.  When using
in
>Parasite power mode (i.e. driven from the 1-wire bus only) Ground and
Vdd
>should be connected together and connected to ground of the RJ11 
Data
>should go to Data.
>


so I should modify Neils ASCII art diagram and tie the unused 3rd leg of
the 
1820 (Vdd) to the ground leg?


>Secondly, are these the DS18S02?  If so, then there is some error
checking
>on-board that, when an error is detected, the device reports a temp of
>+85C.
>Your software will therefore need to interpret this accordingly.
>


The parts I have currently, are just vanilla DS1820, according to whats
laser etched on the flat side of them...


>Additional sensors are wired in parallel on the bus but it has been
>recommended that a Schottky diode is added across the bus (at the
sensor I
>believe) to prevent bus undershoot.  I have not got around to
doing this 
>yet
>despite obtaining the diodes 2 years ago!
>

what's the implication of (not) doing this? - I plan to run between 6 or 8
1820's on the wire...

Incidentally, once I have 8 of these all on the same wire, how do I tell
them apart and read from them individually? - do they all have a hard-coded
unique ID burnt into them or something?

Cheers guys.

Paul G.

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