Max for Live + Arduino

Student in despair... Hello, I'm a final year interaction design student looking to use Max for Live Connection Kit and Arduino to trigger midi files using an omni-polar hall-effect sensor switch. I've used Ableton live before, but this is my first time using the Max for Live Connection Kit to control Arduino. I'm basically wanting to trigger a midi (one shot sample) when the hall effect sensor recognizes a magnet passing by, but then revert to a default (wait) state until the magnet passes by the sensor switch again? For now simply getting the sensor even recognised by the Connection kit would be a great help. I've searched endlessly online for tutorials using magnetic sensors but am unable to work out how this setup would work with the Connection Kit and the mapping parameters? So far I've managed to complete a basic control setup using the 'map' feature, hooking up a potentiometer to control track volume, but when trying to control the hall effect sensor via the analogue pin then triggering a midi file to play, it wont let me map these controls. Ive uploaded the required firmware but the sensor cant be mapped. Is there a way of 'play/stop' controls to be mapped then triggered by a reading from a hall effect/distance sensor? As you can probably tell from the wording of this post, I'm a total beginner with Arduino and processing, so advanced apologies etc but any help in terms of videos, code, tutorials, similar projects or online documentation would be greatly appreciated.