hehe you are absolutely right
so: I am running a CarPc that controls an arduino-board(the MCU). i control the PC, the PC controls the arduino, and the arduino controls many electronics in the car, like power windows or AC. the power windows are controlled, by providing GND to their relay coils (by an NPN transistor)
but since the software is not to be always trusted, i want to also have a hardware solution... hence the switches!
How things where, doesn't matter, since i am planing their new version
my main guideline is to have as less wires as possible running in the car (i already have to many), and this is why i "cant" provide feedback to the MCU (and also because the switches bypass it completely anyway)
i am planing on installing the power window relays, inside the doors, mainly because i have too much space free there
so now if i want to add a feature like "complete roll up/down" the only way i can do this, is by timing... etc by energizing the relay for 4 seconds. but as you can imagine , this does not work so well.. so what i want to do, is set the timing to something like 8seconds, and provide some failsafe, that when the motor stalls, the power will be cut.
i can remove the door panel (obviusly
) but i cant remove the rest of the stuff required, in order to install some hardware "position sensors" in the window..
i can only reach the motor, and this is why i look in a stall current method
P,S 1: i also run fuses, and relay interlocking, but those would just complicate things even more
P.S2: i think that cars, get rid of this problem, by installing some special siwtches in the top and bot of the window track, when the window reaches the max position, it presses the siwtch, and the switch, grounds the motors positive supply... so the only way for the window to move , is the other way