Alexandre...

You don't have to issue a convert command to all 35 sensors at once!

-marc

-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf
Of Alexandre Guimaraes
Sent: Monday, September 06, 2004 6:57 PM
To: Microcontroller discussion list - Public.
Subject: Re: [PIC:] shift register(s) to read temp from 35 DS1820
basedsensors

Hi,

>You've totally lost me here....you only need 2-wires (GND + signal) to
>read all 35 sensors -- that's the idea of the 1-wire bus that Dallas
>developed; it's a mini network.
>Or am I missing something here?

    Take a good look at the datasheet... You need much more power than
the
pull-up can supply to measure the temperature, specially with 35
sensors.
You need to use a active pull-up system or put one more wire to carry
power.. In my opnion I prefer to just put one more wire and be free from
the
trouble...

Best regards,
Alexandre Guimaraes




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