[En-Nut-Discussion] Power Strip Program

[Mark J Elkins]

Thanks for your input Joel - the sort of info I'm looking for!

On Mon, 2006-03-06 at 09:32 -0800, Joel Winarske wrote:

> I've done something similar with DC.  I used D/A with a comparator for each
> channel.  The D/A output was used to dynamically adjust the trip point.  You
> might consider using Hall Effect sensors for current measurement. 

You or someone else mentioned Hall-Effect sensors. Seems like the right
thing to do. Most AVR's have 8 A/D comparators - and as many hall-effect
devices outputs runbetween 0 and 5 volts - the AVR's seem very suitable.
I was looking at measuring a whole bunch of "analogue" inputs...

12 (or so) sockets,
2 input supplies (current)
2 input supplies (voltage)
2 input supplies (frequency)
2 temperature devices
1 smoke detector 
1 humidity level device

I'm not sure if one can "multiplex" the measuring - or whether I'm going
to end up with three AVR's, one master for ethernet and environment and
two measuring current and controlling relays.

I'm open to advice

>  For the
> environmental monitoring side you might consider the Maxim/Dallas 1-Wire
> devices.  You could use either the serial or I2C 1-Wire interface.  
> 
> Then again the Maxim/Dallas DS80C4xx series micro was built for applications
> like this (aka Dallas TINI).

Surfing as I write.

Seems like advanced PIC type devices?

In my simple mind - can't I measure temperature through a resistor +
temperature dependant resistor sitting between Gnd and Positive - and
a/d the middle point? Don't most environmental measurement devices work
in a similar way (changing resistance). (Also trying to keep down costs)

For example - I'm only interested in temp from 10°C to 90°C to a
resolution of about 1°C. Anything above 90°C is a case of switch off the
system ASAP.

Anyway - I'm all ears - especially when it comes to other people's
personal experience.

> 
> Joel
> 
> 
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