THe majority of this project revolves around the Dallas one wire temperature sensor the software for I borrowed heavily from http://www.pjrc.com/teensy/td_libs_OneWire.html

Each project I work on I work on trying to imporve what I do with code and try and understand it better. This time I wanted to look more at using functions - I was wanting to try making use of the abiity of a function to return a value ratherthan use global variables but I didnt quiet get there - maybe next time.

its a fairly sttaight forward code

Upon power up read the temp sensor. If its less than 10deg turn the power to the choke off.

then read the temp sensor every second untill the temp either rises to 20deg or 12000 milliseconds has passed (2 minutes) if either condition is true he power is aplied to the choke and it begins normal opperation.

as the circuit only is required to opperate for a couple of minutes - rather than hold a relay high the whole time I decided to use the normal closed contacts of the relay - this way the relay is only energised for the 2 minutes of opperation - once the time has exipred the circuit is no longer required untill the car is next started.