Am Samstag, 3. März 2007 21:14 schrieb Pedro Côrte-Real:
> Do I need to power the 18B20 with Vcc for this distance?
>
No. Power requirement of the DS18B20 is max. 1.5mA, which causes only a
voltage drop in the mV range even on long and thin 1W and GND lines.
Check for contact problems at the connectors.
> In general what should I look out for in distances over 10 meters?
>
If you power a lot of onewire chips (and peripheals) over a thin, long cable,
the GND niveau at the end of the cable may reach 0.7V due to the current
through it. This disturbs the onewire function for chips at the end of the
cable a lot.
Kind regards
Jan
--
A closed mouth gathers no foot.
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