TARGET APPLICATIONS

Smart Home, constrained industrial environments

Gaming, motion control, head-mounted displays, wearable electronics

Navigation, eCompass, IoT (Internet of Things) sensor data management

The magnetic rotary encoder (MRE) reference design is a smart integrated system for angle measurement. It is composed of a FXOS8700 magnetometer, a Kinetis KL46Z microcontroller built on the ARM® Cortex® M0+ processor and a diametrically magnetized magnet.

The magnetic rotary encoder position sensor detects the absolute angular orientation of an on-axis 2-pole magnet. The absolute angular position can be displayed on different outputs as PWM, SPI, or read directly through the interface (LCD screen or on the Graphical User Interface charts). This technology can be employed in high-accuracy angle position detection and motor control (low rpm) (BLDC motors). All rotary magnetic position sensors can replace both absolute and incremental optical sensors, other magnetic and inductive technologies, potentiometers and magnetic switches.

FEATURES AND BENEFITS

Plug and play

Self-calibration

Angle sensor

Contactless potentiometer

Flexible (air gap, location, magnetic field strength)

PWM angle output

SPI interface

3-axis magnetometer

ARM® Cortex-M0+ core KL46Z MCU

Magnetic Rotary Encoder Reference Design: RD-KL46Z-MRE

Smart angle magnetic sensor

www.nxp.com

Magnetic Angle Sensor

How does it work?

The magnetic rotary encoder is very simple. In fact, the application needs only two components to work: a diametrically magnetized magnet to generate a magnetic field and a magnetometer to measure it.

The magnet is placed just over the magnetometer and the magnet position is calculated though a simple trigonometric equation.

However, when implemented, the physical elements disrupt the magnetic field and bring angular position errors.

The NXP magnetic rotary encoder evaluation board includes a self-calibration algorithm to correct the angle error and offer the best accuracy possible.

The MRE evaluation board has several calibration benefits:

Wireless or contactless angle sensor to simplify mechanical placement and avoid mechanical wear

A flexible air gap between the magnet and the sensor (200 to 600 uT acceptance)

Self-calibration algorithm for precision enhancement

DocumentNumber: SMRTANGMAGSENSLF NXP, the NXP logo and Kinetis are trademarks of NXP B.V. All other product or service names are the property of their respective owners. ARM and Cortex are registered trademarks of ARM Limited (or its subsidiaries) in the EU and/or elsewhere. All rights reserved. © 2016 NXP B.V

MAGNETIC ROTARY ENCODER REFERENCE DESIGN BLOCK DIAGRAM

1.8˝ TFT Display

MagnetometerFXOS8700Q

Push button

LDO

MCUKL46Z256VLL4

MCUPK20DX128VF

M5

BatteryCharger

MC34673AEP

Level Shifter SPI

USB

SPI

External Bus/GPIO UART

UART

PWM

I2C

INT

INT

SPI host

Angle analog output

USB mini-AB

Optional Bluetooth module

NXP Technology

Optional Li-ion

Battery

MAGNETIC ROTARY ENCODER REFERENCE DESIGN BLOCK DIAGRAM