RE: Dallas temp sensors

["K. C. Li" <li@xxxxxxx>]

On Fri, 19 Jul 2002, Jon Whiten wrote:

> replacement that did not connect the DS18S20 vdd to ground.  The
device
> worked very well with the exception of these +85C readings every
few
> minutes.  After connecting Vdd to ground these pretty much
disappeared.

That is interesting. We have never come across the 85 degree C error.
That
might be because we have always been driving the chip with separate
power
and not relying on the parasitic power method.

> Also (I am pretty sure) that in the case of the DS18S20 detecting an
error
> it sends +85C as a valid temp reading (CRC Correct).

It seems like an odd way to signal error condition, particularly it
already has the CRC mechanism. +85C could easily be part of the normal
temperature range for some applications. eg. Engine temperature
management.

Regards,

Kwong Li
li@xxxxxxx
Laser Business Systems Ltd.
http://www.laser.com

Yahoo! Groups Sponsor

ADVERTISEMENT

For more information: http://www.automatedhome.co.uk
Post message: ukha_d@xxxxxxx 
Subscribe:  ukha_d-subscribe@xxxxxxx 
Unsubscribe:  ukha_d-unsubscribe@xxxxxxx 
List owner:  ukha_d-owner@xxxxxxx

Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.