I am doing a project controlling an asynchronous motor 230V / 6Amax with triac which is controlled by a microtrolleur, now I want to add to the circuit a part to detect the zero-current in motor side caused by the presence of Limit switch and inject the result to the microcontroller, can I use the gold shunt resistors or it is mandatory to use a hall effect sensor witch i find them more expensive . i don' have much idea in this type of circuit can someone help please thanks