Re: Thermostat Hysterysis

[Frank Mc Alinden <fmcalind@xxxxxxx>]

Hi Dave / Dean
When i was playing with the atmel stuff i had the same =
problem as Dean just had some basic stuff happening and when compiled said
=
that nearly all the memory was used??? Obviously i was doing something
wron=
g??....Would love to have a go at the Can_Bus stuff...is it hard
??.......(=
using pic,s ;-))..)

Frank
----- Original Message -----=20
From: Dave McLaughlin=20
To: ukha_d@xxxxxxx=20
Sent: Tuesday, October 07, 2003 6:52 PM
Subject: RE: [ukha_d] Thermostat Hysterysis


Hi Dean,

I use a 2 degree hysterisis. At present it is only used to operate an
electric heater in my loft, where my computer and HA system lives. To sav=
e
code space, I didn't use an LCD and stored the temp as an integer times 1=
0.
The DS18S20 only changes by 0.5 degrees anyway so this is ideal. The CAN =
Bus
interface code is quite compact as it uses the filters built into the CAN
controller to receive any new messages for the setup etc. Haven't really
done much more than this at present. The relay output is fed into Homesee=
r
via Justin's gameport plugin.

I programme in C using the excellent Codevision compiler so I can't reall=
y
comment on code optimisation other than ask how you store the value in th=
e
software and if maybe using integers might compact it up more?

Regards
Dave...
PS.. My embeddedcomputer.co.uk website is back up now if you want to have=
a
look at the CAN bus stuff. I am looking at doing some simple room
thermostats using the ATMega16 and a 2 digit LED display as I wanted an
excuse to use the new blue seven segment displays from Farnell :o)
---
Very funny Scotty, now beam down my clothes!!!
---


-----Original Message-----
From: Dean Smith [mailto:ukha@xxxxxxx]
Sent: 06 October 2003 20:38
To: ukha_d@xxxxxxx
Subject: RE: [ukha_d] Thermostat Hysterysis


Dave

Do you implement any hold time on the heating on/off state ? i.e. It ca=
n
only change 1 a minute etc. or do you rely on the general hysteresis of
the
house to ensure the thermostat cant cycle on/off too quickly ?

I have working code for :- Reading the DS1820 and displaying to a 2 lin=
e
LCD
+ RS232 Comms for Parameter Setup/Temperature interogation

Which is now 99% of the available flash on a 2313 using BASCOM-AVR. Any
hints and tips for code optimisation !

Thanks
Dean
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