The technology provides for a magnetic sensing device. The device includes a magnetic sensor configured to generate a first output triggered by a first polarity and a second output triggered by a second polarity. The device includes a first magnet, a second magnet, and a third magnet. The device may be configured such that, when the second magnet is not within a predetermined distance from the first magnet, a magnetic field from the first magnet having the first polarity causes the first output and the second output to have a first set of values. The device may be configured such that, when the second magnet is within the predetermined distance from the first magnet, a magnetic field from the third magnet having the second polarity causes the first output and the second output to have a second set of values.