10 min

Fine-tune performance with unipolar Hall switch, the US5881 and STM32F373RC

Unipolar brilliance!

UNI HALL Click with Fusion for STM32 v8

Published Jun 20, 2023

Click board™


Development board

Fusion for STM32 v8


NECTO Studio



Elevate your design with high-performance Hall switch technology



Hardware Overview

How does it work?

UNI HALL Click is based on the US5881, a unipolar Hall-effect switch designed in mixed signal CMOS technology from Melexis Technologies. The US5881 comes with very low magnetic sensitivity based on mixed-signal CMOS technology. It integrates a voltage regulator, a Hall sensor with a dynamic offset cancellation system, a Schmitt trigger, and an open-drain output driver, all in a single package. Its sensitivity enables high accuracy in position sensing by using a small air gap, making it suitable for various automotive, consumer, and industrial applications. The US5881 exhibits

unipolar magnetic switching characteristics. Therefore, it operates only with one magnetic pole – North. Applying a North magnetic pole greater than a magnetic operating point of 25mT, facing the branded side of the package, switches the output of the US5881 to a LOW logic state. In this way, it is possible to determine the pole of the magnet using the information that the host MCU receives from the sensor via the INT line of the mikroBUS™ socket. It is also possible to visually identify the magnet's North Pole via an onboard red LED. Removing the magnetic field switches

the output HIGH. The opposite magnetic pole facing the branded side does not affect the output state. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the LOGIC LEVEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. However, the 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.

UNI HALL 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

Power Supply
Hall Switch Output
Power Supply

Take a closer look


UNI HALL 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 UNI Hall Click driver.

Key functions:

  • unihall_detecting_magnetic_fields - Detecting North pole magnetic fields status function

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 
 * \brief UNI HALL Click example
 * # Description
 * This is a example which demonstrates the use of UNI HALL Click board.
 * The demo application is composed of two sections :
 * ## Application Init 
 * Initialization driver enable's - GPIO and start write log.
 * ## Application Task  
 * Detect the north pole magnetic fields near the UNI HALL Click.
 * Results are being sent to the Usart Terminal where you can track their changes.
 * All data logs on usb uart when magnetic field is detected.
 * \author Mikroe Team
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "unihall.h"

// ------------------------------------------------------------------ VARIABLES

static unihall_t unihall;
static log_t logger;

static uint8_t unihall_state;
static uint8_t unihall_state_old;

// ------------------------------------------------------- ADDITIONAL FUNCTIONS

// ------------------------------------------------------ APPLICATION FUNCTIONS

void application_init ( void )
    log_cfg_t log_cfg;
    unihall_cfg_t cfg;

     * 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_printf(&logger, " --- Application Init ---\r\n");

    //  Click initialization.

    unihall_cfg_setup( &cfg );
    unihall_init( &unihall, &cfg );

    unihall_state = UNIHALL_NORTH_POLE_DETECTED;
    unihall_state_old = UNIHALL_NORTH_POLE_DETECTED;

    log_printf(&logger, "---------------------------\r\n");
    log_printf(&logger, "        Initialization     \r\n");
    log_printf(&logger, "---------------------------\r\n");
    log_printf(&logger, " Detecting magnetic fields \r\n");
    log_printf(&logger, "---------------------------\r\n");

    Delay_ms( 100 );

void application_task ( void )
    unihall_state = unihall_detecting_magnetic_fields( &unihall );

    if ( ( unihall_state == UNIHALL_NORTH_POLE_NOT_DETECTED ) && ( unihall_state_old == UNIHALL_NORTH_POLE_DETECTED ) )
        unihall_state_old = UNIHALL_NORTH_POLE_NOT_DETECTED;
        log_printf(&logger, "      ~ NOT DETECTED ~\r\n");

    if ( ( unihall_state == UNIHALL_NORTH_POLE_DETECTED ) && ( unihall_state_old == UNIHALL_NORTH_POLE_NOT_DETECTED ) )
        log_printf(&logger, "        ~ DETECTED ~\r\n");
        unihall_state_old = UNIHALL_NORTH_POLE_DETECTED;

void main ( void )
    application_init( );

    for ( ; ; )
        application_task( );

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

Additional Support