Help with word variable

[Art]

So using the formula that results in 280-2768 which results in a negative figure. What I need to do is to make TempC into a 3 digit value, 276, so that when the equation is run I get a positive error, 280-276=4.

Can’t you either divide the 2768 by 10, or multiply the 280 by 10 first?

[Scampy]

Well I did say it was late !

OK that works - and gives a better result for when the current temperature is below the set point, but gives values of 655xx when the curent temp exceeds the setpoint. Also the heatdriver that controlls the LED on port D4 doesn't work as it should. It should be on constant, and then start pulsing at around 1sec frequency as the temperature nears the set point, with the pulse duration getting shorter as the difference between the current temperature and setpoint gets smaller.

I've attached the PID include file hoping someone can advise

[richard]

a pid_out of 65535 would be interpreted as - 1 by your code and therefore ignored

ASM
HeaterDrive
........

you have no code to call this routine
as well as no interrupt code at all that might call it either