Re: Temperature Monitoring - 1-Wire or other solution?

[Jim Noble <yahoo-groups@xxxxxxxxxxxxxxxxxx>]

Ben McCormack wrote:
> Jim - When you say quit slow what do you mean? Lets say I had 20 temp
> sensors.
>

My understanding of it:

To read a temperature, you send a conversion command to the sensor, and
then read the temperature back when the conversion is done. This takes
"about" a second. If you are using parasitic power (where the
sensor
draws power from the bus signal) the bus is unavailable while the
conversion is happening, so you have to twiddle your thumbs while each
conversion takes place, and the time to read all the sensors on the bus
scales linearly with the number of sensors you're trying to read.

If you use powered mode (where you supply power on a 3rd wire), the bus
remains available during the conversion though, so you can do cunning
things like requesting the conversion from a bunch of sensors, then
going back and reading the result in the same order you requested them
"about" a second later...

Jim

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