[tech] temperature logging

[Adrian Chadd]

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. :)




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