Field test. (Sort of)
Success! (Sort of...)
This morning I drove to work wearing the heater liner under my leather jacket.
It was wired to prototype controller...
And everything worked just fine!
I think I need to cut about 5cm off from heater wires because it took about 6 minutes for the liner to heat up.
If I shorten the wire, it will heat up more quickly but it will also generate more heat. And that is a problem if the controller decides to give it full power.
Currently MOSFETs in controller do have a pull-down resistor just in case if MCU leaves gate control pin floating but what if MCU dies and pulls pin up? Hmmm....
Do I need to add another MCU to circuit to keep the "main" MCU an eye and shut system down if needed?