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I’m building a small maze solving micromouse and I’m using some of those tiny 8x20mm coreless DC motors for the drive. The space constraints are tight on the robot, width is about 4cm and length 6cm. I would like to add some encoders to the motors so I could keep better track of the robots location, so I was thinking could a hall effect sensor read the rpm of the motor rotor? I couldnt find any info on the magnetic fields that a motor like this gives out, so I have no clue. Someone suggested an optical encoder but again the space constraint is tight and DIY photoresistor encoder would probably be more error prone. Does anyone have more info on the magnetic fields outside of such a motor, or parts on hand to try it?