I have put together a room thermostat.
1" LED display, controlled from SA1064 chip.
20X2 picaxe controller.
Base default temperature is 18 C. rises to 21 C at pre defined times.
Panel controls can set 18C, 21C, or +- steps of 0.1C.
Voltage free contacts for control of zone valve/ boiler.
OLED display plugs into control box for setup / time set. (2.5mm stereo plug)
12v power plugs into control box, 7805 regulator added.
Programming lead, plugs into control box, (3.5mm stereo plug)
I'm still experimenting as to where to place the DB1820 sensor.
Can also be adjusted using a remote I/R handset. for setting temperature and time.
See here for the excellent tutorial by westaust55,
http://www.picaxeforum.co.uk/showthread.php?22252-Getting-Started-with-the-SAA1064-i2c-bus-4-Digit-7-Segment-LED-driver-chip&highlight=sa1064
Word/Byte/Bit table
Program listing
View attachment Thermostat.bas
I'd post the listing but it exceeds the 10000 character limit.
230vac relay box on top, control box below, plugs right hand side.
View attachment 15345
Control panel, top right I/R receiver.
top left DB1820 sensor, mistake putting it here.
Manual buttons at base.
(tried touch pads, but faceplate too thick, and 20X2 doesn't support 'touch')
View attachment 15346