RE: Dallas temp sensors

["Jon Whiten" <jon@xxxxxxx>]

> -----Original Message-----
> From: Paul Gordon [mailto:paul_gordon@xxxxxxx]
> Sent: 19 July 2002 09:53
> To: ukha_d@xxxxxxx
> Subject: RE: [ukha_d] Dallas temp sensors
>
>
> so I should modify Neils ASCII art diagram and tie the unused 3rd
> leg of the
> 1820 (Vdd) to the ground leg?
>


Yes


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

The DS1820 does not have the error checking.  I have somewhere a
report from
Dallas regarding the problems with the DS1820 I can let you have if you
like.

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

I think it is down to the reliability of the reading of the bus.
Particularly if, although the sensors are in parallel, they are located
on
spurs off the main bus.

>
> 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?

Each has a unique ID hard-coded into the device.


> Cheers guys.
>
> Paul G.
>

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