I have a gearbox which transforms the rotational movement to linear movement. It drives a pin which moves back and forward using a DC motor.

I need to know when the pin reaches the two "end-stops" (full back/full forward).

The motor is a simple brushed one and there're no sensors to detect pin position (and not enough space to add them), so I though to measure the motor current and when I read a fast increment it means the pin is full forward/backward.

The motor is 3V low speed and the current (free movement) is around 11.8mA.

How can I measure the current and read by a microcontroller to drive the motor via H-bridge? It will be cool to have an IC (eg. controlled via I2C) which act as H-bridge and current meter.


1 Answer 1


In order to measure current you have to use Current Transducer, such as this. Or a Hall Effect sensor, or a shunt resistor, or something similar.

The thing is that all of these methods are quite complicated, compared to what you are trying to achieve. Just install two terminal switches at both ends and read their state.


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