[tech] temperature logging

[Trent Lloyd]

On Mon, Jul 11, 2005 at 10:05:28AM +0800, Adrian Chadd wrote:
> 
> amusingly, this is about the kind of thing I was going to build
> tomorrow using an AVR. It shouldn't take too much effort to make
> an 8 port input/8 port output device. Temperature sensoring is
> available, as the AT90S8535/ATMega8535 has 8 ADCs.
> 
> Tis up to you all. I think electronic projects are fun. :)

Thats what I thought but davyd seems to think using a premade board is
better cus its cheaper and wasted effort to re-invent the wheel. :)

Cheers,
Trent

> 
> 
> 
> 
> Adrian
> 
> On Sun, Jul 10, 2005, Davyd Madeley wrote:
> > I acquired a serial I/O board on loan from work (will have to buy
> > them a new one). This board offers 8 bits of digital I/O and two 8
> > bit ADCs.
> > 
> > One of these ADCs is now connected to a thermal sensing
> > semiconductor. The board is connected via RS-232 to Centipede, the
> > DECserver in the tall rack.
> > 
> > To read the temperature:
> >  llogin THERMAL			<-- connect to the board over LAT
> >  rd0				<-- read port 0
> >   (the decimal representation of a byte will be displayed, close the
> >    connection - ^] on mussel)
> >  dc				<-- everyone's favourite calculator
> >  $reading 139 - 0.512 / p
> >   (prints the temperature in celsius)
> > 
> > It's only accurate to about 2 deg C according to the appropriate
> > datasheets, so the decimal places aren't that important.
> > 
> > It's currently connected using an Eric, because I couldn't find
> > enough appropriate serial to connect it, specifically a DB-9 gender
> > bender. It's also connected to a 9V plugpack via a 110V stepdown
> > transformer, as I couldn't find a 9V pack designed for Australian
> > voltages.
> > 
> > If we want, it would be very easy to tie the door sensors into this
> > thing using some 10k resistors (to stop the inputs floating). It can
> > also provide enough current to drive a solid state relay (for the
> > door lock) and has another ADC, if we wanted a second temperature
> > sensor.
> > 
> > The machine room is a pleasant 35C at the moment. This has not been
> > tested against another thermometer.
> > 
> > --d

-- 
Trent Lloyd <lathiat at bur.st>
Bur.st Networking Inc.