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Rotor Position Encoder


dev_motor_controller_4808 incorporates an integrated rotor position encoder based on the Austria Micro AS5047p magnetic encoder. The AS5047p device returns 14 bits of rotational position at a maximum rate of 28k RPM.

Encoder Target

AS5047p magnetic target

The AS5047p returns the position of a diametrically magnetised cylindrical magnet mounted to a rotating structure at a fixed distance from the surface of the sensor.

Magnet type Cylindrical diametrically magnetised Neodymium Iron Boron (NdFeB) N35
Potential part number Radial Magnets Inc 9042, Digikey 469-1070-ND

Magnet mounting requirements

In practice the AS5047p is quiet tolerant to magnet misalignment and in most cases will produce a reasonable output. Mounting guidelines are presented below.

Vertical mounting distance Between 0.5mm and 1.8mm from the surface of the sensor
Suggested magnet size 6mm diameter, >= 2.5mm height
Bz (Orthogonal magnetic field strength) 35mT - 70mT peak field strength at a radius of 1.1mm

For further detailed information consult the AustriaMicroSystems AS5047p datasheet. Although it is a different sensor the AS5040 datasheet also offers useful mounting guidelines.

Magnet mounting example

Magnet mounting example