30 min

Ensure precise measurements over the full spectrum of magnet rotation with AEAT-9922 and STM32F373RC

360 degrees of precision

Magnetic Rotary 2 Click with Fusion for STM32 v8

Published Sep 28, 2023

Click board™

Magnetic Rotary 2 Click

Development board

Fusion for STM32 v8


NECTO Studio



Our angular magnetic rotary sensor sets a new standard for accuracy, providing seamless and precise angular measurements over a full 360 degrees of magnet rotation



Hardware Overview

How does it work?

Magnetic Rotary 2 Click is based on the AEAT-9922, an angular magnetic rotary sensor manufactured with a CMOS standard process providing accurate angular measurement over a full 360 degrees of rotation from Broadcom Limited. It can accurately measure a magnet's rotational angle when aligned and perpendicular to the device by using its integrated Hall sensors to detect its magnetic field. The detected magnetic signals are then taken as input signals to be properly conditioned to negate their non-idealities before inputting them into the analog amplifiers for strength amplification and filtering. After which, the amplified analog signals are fed into the internal analog-to-digital converter (ADC) to be converted into digital signals for the final digital processing stage. A simple two-pole magnet generates the necessary magnetic field by rotating it perpendicularly. Wide magnetic field sensor configurations allow On-Axis (end of shaft) or Off-Axis (side of the shaft) modes in application. The used magnet should have sufficient

magnetic field strength (mT) to generate the magnetic field for signal generation. The device provides digital information of magnetic field strength high and magnetic field strength low to indicate whether the magnets are too close or far away from our device's surface. Magnetic Rotary 2 Click communicates with MCU through a standard SPI interface supporting the common SPI mode, SPI Mode 1. Digital processing provides a digitized output of the absolute and incremental signals. Each output is configurable via CS pin, MSEL (Mode Selection for desirable protocol) jumper, and AEAT-9922 internal PSEL registers configurable through memory. In addition, an absolute angular representation can also be selected using a pulse width modulated (PWM) signal by populating an onboard R2 resistor, which provides an instant indication of the magnet's angular position with a selectable and one-time programmable resolution from 10 to 18 bits. Alongside this feature, the communication error signal labeled as ERR and routed on the INT pin of

the mikroBUS™ socket can be activated by populating the onboard R3 resistor. The incremental outputs are available from digital outputs of their respective A, B, and I pins, the same for the U, V, and W commutation signals routed to the upper-right side onboard header. The incremental positions are indicated on ABI and UVW signals with a comprehensive user-configurable resolution from 1CPR, up to 10,000CPR of ABI signals, and pole pairs from 1 to 32 pole pairs (from 2 to 64 poles) for UVW commutation signals. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. Also, this Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used as a reference for further development.

Magnetic Rotary 2 Click hardware overview image

Features overview

Development board

Fusion for STM32 v8 is a development board specially designed for the needs of rapid development of embedded applications. It supports a wide range of microcontrollers, such as different 32-bit ARM® Cortex®-M based MCUs from STMicroelectronics, regardless of their number of pins, and a broad set of unique functions, such as the first-ever embedded debugger/programmer over WiFi. The development board is well organized and designed so that the end-user has all the necessary elements, such as switches, buttons, indicators, connectors, and others, in one place. Thanks to innovative manufacturing technology, Fusion for STM32 v8 provides a fluid and immersive working experience, allowing

access anywhere and under any circumstances at any time. Each part of the Fusion for STM32 v8 development board contains the components necessary for the most efficient operation of the same board. An advanced integrated CODEGRIP programmer/debugger module offers many valuable programming/debugging options, including support for JTAG, SWD, and SWO Trace (Single Wire Output)), and seamless integration with the Mikroe software environment. Besides, it also includes a clean and regulated power supply module for the development board. It can use a wide range of external power sources, including a battery, an external 12V power supply, and a power source via the USB Type-C (USB-C) connector.

Communication options such as USB-UART, USB HOST/DEVICE, CAN (on the MCU card, if supported), and Ethernet is also included. In addition, it also has the well-established mikroBUS™ standard, a standardized socket for the MCU card (SiBRAIN standard), and two display options for the TFT board line of products and character-based LCD. Fusion for STM32 v8 is an integral part of the Mikroe ecosystem for rapid development. Natively supported by Mikroe software tools, it covers many aspects of prototyping and development thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.

Fusion for STM32 v8 horizontal image

Microcontroller Overview

MCU Card / MCU



8th Generation


ARM Cortex-M4

MCU Memory (KB)


Silicon Vendor


Pin count


RAM (Bytes)


Used MCU Pins

mikroBUS™ mapper

SPI Chip Select
SPI Clock
Power Supply
PWM Signal
Communication Error
Power Supply

Take a closer look


Magnetic Rotary 2 Click Schematic schematic

Step by step

Project assembly

Fusion for PIC v8 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Fusion for STM32 v8 as your development board.

Fusion for PIC v8 front image hardware assembly
Buck 22 Click front image hardware assembly
SiBRAIN for PIC32MZ1024EFK144 front image hardware assembly
v8 SiBRAIN MB 1 - upright/background hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
NECTO Compiler Selection Step Image hardware assembly
NECTO Output Selection Step Image hardware assembly
Necto image step 6 hardware assembly
Necto image step 7 hardware assembly
Necto image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Necto PreFlash Image hardware assembly

Track your results in real time

Application Output

After pressing the "FLASH" button on the left-side panel, it is necessary to open the UART terminal to display the achieved results. By clicking on the Tools icon in the right-hand panel, multiple different functions are displayed, among which is the UART Terminal. Click on the offered "UART Terminal" icon.

UART Application Output Step 1

Once the UART terminal is opened, the window takes on a new form. At the top of the tab are two buttons, one for adjusting the parameters of the UART terminal and the other for connecting the UART terminal. The tab's lower part is reserved for displaying the achieved results. Before connecting, the terminal has a Disconnected status, indicating that the terminal is not yet active. Before connecting, it is necessary to check the set parameters of the UART terminal. Click on the "OPTIONS" button.

UART Application Output Step 2

In the newly opened UART Terminal Options field, we check if the terminal settings are correct, such as the set port and the Baud rate of UART communication. If the data is not displayed properly, it is possible that the Baud rate value is not set correctly and needs to be adjusted to 115200. If all the parameters are set correctly, click on "CONFIGURE".

UART Application Output Step 3

The next step is to click on the "CONNECT" button, after which the terminal status changes from Disconnected to Connected in green, and the data is displayed in the Received data field.

UART Application Output Step 4

Software Support

Library Description

This library contains API for Magnetic Rotary 2 Click driver.

Key functions:

  • magneticrotary2_write_register - This function writes a data byte to the selected register by using SPI serial interface

  • magneticrotary2_read_register - This function reads a data byte from the selected register by using SPI serial interface

  • magneticrotary2_get_angle - This function reads the absolute position raw data and converts it to degrees (Angle)

Open Source

Code example

This example can be found in NECTO Studio. Feel free to download the code, or you can copy the code below.

 * @file main.c
 * @brief MagneticRotary2 Click example
 * # Description
 * This example demonstrates the use of Magnetic Rotary 2 click board by reading and displaying
 * the magnet's angular position in degrees.
 * The demo application is composed of two sections :
 * ## Application Init
 * Initializes the driver and performs the click default configuration.
 * ## Application Task
 * Reads the magnet's angular position in degrees every 100ms and displays the results on the USB UART.
 * @author Stefan Filipovic

#include "board.h"
#include "log.h"
#include "magneticrotary2.h"

static magneticrotary2_t magneticrotary2;
static log_t logger;

void application_init ( void )
    log_cfg_t log_cfg;  /**< Logger config object. */
    magneticrotary2_cfg_t magneticrotary2_cfg;  /**< Click config object. */

     * Logger initialization.
     * Default baud rate: 115200
     * Default log level: LOG_LEVEL_DEBUG
     * @note If USB_UART_RX and USB_UART_TX 
     * are defined as HAL_PIN_NC, you will 
     * need to define them manually for log to work. 
     * See @b LOG_MAP_USB_UART macro definition for detailed explanation.
    LOG_MAP_USB_UART( log_cfg );
    log_init( &logger, &log_cfg );
    log_info( &logger, " Application Init " );

    // Click initialization.
    magneticrotary2_cfg_setup( &magneticrotary2_cfg );
    MAGNETICROTARY2_MAP_MIKROBUS( magneticrotary2_cfg, MIKROBUS_1 );
    if ( SPI_MASTER_ERROR == magneticrotary2_init( &magneticrotary2, &magneticrotary2_cfg ) )
        log_error( &logger, " Communication init." );
        for ( ; ; );
    if ( MAGNETICROTARY2_ERROR == magneticrotary2_default_cfg ( &magneticrotary2 ) )
        log_error( &logger, " Default configuration." );
        for ( ; ; );
    log_info( &logger, " Application Task " );

void application_task ( void )
    float angle = 0;
    if ( MAGNETICROTARY2_OK == magneticrotary2_get_angle ( &magneticrotary2, &angle ) )
        log_printf( &logger, " Angle: %.2f degrees\r\n\n", angle );
        Delay_ms ( 100 );

void main ( void )
    application_init( );

    for ( ; ; )
        application_task( );

// ------------------------------------------------------------------------ END

Additional Support