Heating pause relay, prevent heating escalation

This software is written for the atmeag328p microcontroller.

Description of the functionallity:
If the circuit is powered then the relay goes on. If the circuit
is not powered then the relay is off. If the circuit is powered
for more than 60min then the relay goes off for 3min. During this
time the green led blinks indicating that were are in the pause period.

There are 3 red leds which function as a binary counter counting how often
a pause was executed.

Switch S1 may be closed to have the relay always on when the power is on.
In other words no pause is done when S1 is closed. The red led pause counter 
does however still count the number of hours and the green led binks during the
pause period but the relay does not go off.

The idea is that this circuit replaces a relay which controls a Thermolec T-18
heater which has two heating sources (electric and oil or propane). 
The heater starts when the relay that this circuit controls closes (the pins
where this relay connects are called C and W on the heater).
The heater has also a separate sensor input which controls the heat source. 
However the heater has has a feature called auto-switch which can not be turned
off. When it has been heating for more than 2 hours (or 4h, can be configured) 
continously then it does an auto-switch from electric to oil/propane even if the
control system did not request oil/propane.

This software and circuit prevents the auto-switch of the Thermolec heater
by pausing it for 3min every hour.

Pre-compiled software
The software comes with a pre-compiled heating-pause.hex file which you
can load directly to the microcontroller. All the avr fuse bit remain
at factory default. You don't need to change any of those. 

Mac and Linux
To compile type the command:
make

To compile and load use:
make load

Windows
If you run Windows and you have winavr installed then check the winmake.bat
file. Edit it and adjust the path as needed. After that just double click
on the winmake.bat file to compile.



History:
version 0.1: 2025-01-05, first Version
version 0.2: 2025-01-11, Change pause time from 5min to 3min
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Copyright: GPL
Written by guido socher 
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