This code runs a pic16f628a as a controller for a Sous-Vide water bath. It's assumed that pin A3 is used as the output driving a relay which turns on the heating element (and possibly circulation pump), and comparator 2 is used to compare the output of a temperature sensor (I use an LM335) to a reference voltage (e.g., generated with a potentiometer).
This code is basically just a debouncer. If you wanted to invert the sense of this and use it, e.g., to control a freezer at a particular temperature, you'd swap the polarity of the inputs to the comparator. You'd probably have to add a lockout interval (e.g., the relay is locked into its present position for a few minutes after each time it switches) so you don't destroy the compressor by short-cycling it. Most compressors have a short-cycle switch built into them, but there's no reason to take chances.
This code should assemble just fine with gpasm. See the Makefile for details.
sousvide628 is free software. It comes without any warranty, to to the extent permitted by applicable law. You can redistribute it and/or modify it under the terms of the Do What The Fuck You Want To Public License, Version 2, as published by Sam Hocevar. See http://sam.zoy.org/wtfpl/COPYING for more details