I did one application with 4 DS18S20's, and since the temperature change
wasn't all that dynamic, I set up a 1 second interrupt, where I would cycle
through the 4 sensors.  I basically built in a "lag", where at each 1
second interrupt, I'd start a conversion on one sensor, then read the
previous sensor which had gotten it's start conversion command on the
previous 1 second interrupt.
Worked pretty well for me, but like I said, it was a slow enough system
that reading each sensor once every 4 seconds was still ok.

-Mark


At 09:56 AM 4/9/02 +1000, you wrote:
>Hi all,
>
>I've been putting together a small data logger application that uses 4
>of the DS18S20 1 wire temp sensors, a Honeywell humidity sensor and two
>electronic scales that I talk to with bit banged RS232 code. I then
>relay the results to the PC via the UART, or just store to local I2C
>memory for portabillity.
>
>The data sheet says 750mS to get each temp conversion and some people
>here want to use the logger with more temp sensors. The trouble is the
>acquisition time goes up substantially and you can't really say that the
>temps were all logged at exactly X time.
>
>Is there any way around this that anyone knows of.
>
>Assuming someone knows the DS18S20, I was wondering if you could use a
>bypass ROM command and start the conversions all together, and then read
>individually after just a single 750mS conversion???
>
>--
>Best regards
>
>Tony
>
>mICros
>http://www.bubblesoftonline.com
>mailto:sales@bubblesoftonline.com
>
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-------------------------------------------
Mark Samuels
ARMA Design
Tel:(858) 373-1320
Fax:(858) 373-1325
Email: mark@armanet.com
Web: www.armanet.com



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