hias9 said:
On the ASI I have tested to wire a resistance in series with the signal cable.
that's not how it would be wired in your idea, assumign the resistance is intended to simulate the thermal sensor.
you'd be directly wiring the resistance of the thermal sensor in parallel with the speed signal to ground.
if you don't, then the temperature sensor input can't read the sensor, since that's how most of them are designed to work--with the sensor from signal to ground. unless the asi is different, in which case you must find out how it works.
if you really want to know if it would work the way you want, you would literally short the controlelrs' speed sensor input and thermal sensor input, and also short the motor's speed sensor output and it's thermal sensor output, and connect those two signal wire sets together.
the internal electronics (pullups, pulldowns, residual voltages, etc) on each controller input affect the circuit, as do the actual thermal sensor and speed sensor used, as well as how long the sensor stays grounded on each rotation and how many times it is grounded per rotation,
either way, the temperature sensors resistance will be affected, so you would have to determine experimentally what the reading the controller will see and then calculate what to program the controller to expect from the sensor (assuming it has a way to do that, and doesn't just expect a certain specific sensor range).
the same is true of the voltage from a thermal sensor like lm35--it won't read quite the same as it would otherwise, so to get correct readings you have to experimentally calibrate the controller to read correctly, assuming it has that capability.
the speed sensor may or may not work at all, depending on how well the thermal senosr grounds the signal, at the temperature ranges you expect to see in the motor, and how much voltage the controller requires to see during a non-pulse state. (since it reads a pulse anytime it's below 1.8v, it proably has a similar type of threshold for a non-pulse state, more toward the 5v end of things, and likely wont' read another pulse until it has transitioned above that level for whatever amount of time, depending on it's noise-rejection software/hardware setup.
To measure the motor temp, it uses the analog voltage of the signal cable to GND.
then that means you must have a sensor inside the motor like the lm35 that outputs a voltage. is that what you have? or do you have a resistance to ground that varies with temperature (much more common).
Regarding the circuit, that sounds complicated and it would have to be inside the motor.
yes. half would be inside the motor (multiplexer) and half would be outside the motor (demultiplexer). requires both to work. and yes, it would be complicated.
I would prefer a simplier solution. Motor temp does not have to be very exact. Only enough to detect overheating.
drill a hole in the motor case and use laser-ir sensor with a fast enough reaction time to read teh temperature while the hole is in line with it.
personally i'd rather just take the speed sensor wire in the motor already, and use it for the thermal sensor exclusively.
then stick a magnet on the wheel itself, or a series of them, and use an external speed sensor, to completely avoid the whole complicated mess.
is there a reason you won't or can't do that?