Beginner
10 min

Navigate with ease using our LED-encircled rotary solution based on the EC12D1564402 and STM32F302VC

Go green, go rotary!

ROTARY G Click with CLICKER 4 for STM32F302VCT6

Published Jul 22, 2025

Click board™

ROTARY G Click

Dev. board

CLICKER 4 for STM32F302VCT6

Compiler

NECTO Studio

MCU

STM32F302VC

Elevate your experience with our revolutionary rotary solution, guided by a luminous green LED circle of trust

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Hardware Overview

How does it work?

ROTARY G Click is based on two SN74HC595 SPI-configurable 8-bit shift registers from Texas Instruments that, combined with a high-quality rotary encoder, the EC12D1564402, allows you to add a precision input knob to your design. The EC12D1564402 incremental rotary encoder is surrounded by a ring of 16 green LEDs where a single rotation is divided into 15 discrete steps (in contrast to a potentiometer, a rotary encoder can be spun around continuously). This Click board™ is an ideal solution for building various HMI applications where precise input is required, but also for some interesting visual effects to any application. As mentioned, this Click board™ uses

the EC12D1564402, a 15-pulse incremental rotary encoder with a push-button, from ALPS. This encoder has unique mechanical specifications (debouncing time for its internal switches goes down to 2ms) and can withstand many switching cycles, up to 30.000. The supporting debouncing circuitry allows contacts to settle before the output is triggered fully. The SN74HC595 controls each LED individually positioned in a ring around the encoder through a standard SPI interface with a maximum frequency of 5MHz. Rotating the encoder, it outputs A and B signals (out of phase to each other) on the two mikroBUS™ lines, AN and PWM pins of the mikroBUS™ socket,

alongside the push-button contact, which outputs through the interrupt line of the mikroBUS™ socket. The SN74HC595 also has a Reset feature used across the RST mikroBUS™ line. This Click board™ can operate with both 3.3V and 5V logic voltage levels selected via the PWR SEL jumper. This way, it is allowed for both 3.3V and 5V capable MCUs to 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.

ROTARY G Click hardware overview image

Features overview

Development board

Clicker 4 for STM32F3 is a compact development board designed as a complete solution, you can use it to quickly build your own gadgets with unique functionalities. Featuring a STM32F302VCT6, four mikroBUS™ sockets for Click boards™ connectivity, power managment, and more, it represents a perfect solution for the rapid development of many different types of applications. At its core, there is a STM32F302VCT6 MCU, a powerful microcontroller by STMicroelectronics, based on the high-

performance Arm® Cortex®-M4 32-bit processor core operating at up to 168 MHz frequency. It provides sufficient processing power for the most demanding tasks, allowing Clicker 4 to adapt to any specific application requirements. Besides two 1x20 pin headers, four improved mikroBUS™ sockets represent the most distinctive connectivity feature, allowing access to a huge base of Click boards™, growing on a daily basis. Each section of Clicker 4 is clearly marked, offering an intuitive and clean interface. This makes working with the development

board much simpler and thus, faster. The usability of Clicker 4 doesn’t end with its ability to accelerate the prototyping and application development stages: it is designed as a complete solution which can be implemented directly into any project, with no additional hardware modifications required. Four mounting holes [4.2mm/0.165”] at all four corners allow simple installation by using mounting screws. For most applications, a nice stylish casing is all that is needed to turn the Clicker 4 development board into a fully functional, custom design.

CLICKER 4 for STM32F302VCT6 double image

Microcontroller Overview

MCU Card / MCU

STM32F302VC Image

Architecture

ARM Cortex-M4

MCU Memory (KB)

256

Silicon Vendor

STMicroelectronics

Pin count

100

RAM (Bytes)

40960

Used MCU Pins

mikroBUS™ mapper

Encoder Output B
PC4
AN
Reset
PC15
RST
SPI Chip Select
PA4
CS
SPI Clock
PA5
SCK
SPI Data OUT
PA6
MISO
SPI Data IN
PA7
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
Encoder Output A
PE9
PWM
Knob Detection
PD0
INT
NC
NC
TX
NC
NC
RX
NC
NC
SCL
NC
NC
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

ROTARY G Click Schematic schematic

Step by step

Project assembly

PIC32MZ MXS Data Capture Board front image hardware assembly

Start by selecting your development board and Click board™. Begin with the CLICKER 4 for STM32F302VCT6 as your development board.

PIC32MZ MXS Data Capture Board front image hardware assembly
Thermo 21 Click front image hardware assembly
Thermo 21 Click complete accessories setup image hardware assembly
Board mapper by product6 hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
Necto image step 5 hardware assembly
Necto image step 6 hardware assembly
PIC32MZ MXS Data Capture Board NECTO MCU Selection Step hardware assembly
Necto No Display image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Necto image step 11 hardware assembly

Track your results in real time

Application Output

1. Application Output - In Debug mode, the 'Application Output' window enables real-time data monitoring, offering direct insight into execution results. Ensure proper data display by configuring the environment correctly using the provided tutorial.

2. UART Terminal - Use the UART Terminal to monitor data transmission via a USB to UART converter, allowing direct communication between the Click board™ and your development system. Configure the baud rate and other serial settings according to your project's requirements to ensure proper functionality. For step-by-step setup instructions, refer to the provided tutorial.

3. Plot Output - The Plot feature offers a powerful way to visualize real-time sensor data, enabling trend analysis, debugging, and comparison of multiple data points. To set it up correctly, follow the provided tutorial, which includes a step-by-step example of using the Plot feature to display Click board™ readings. To use the Plot feature in your code, use the function: plot(*insert_graph_name*, variable_name);. This is a general format, and it is up to the user to replace 'insert_graph_name' with the actual graph name and 'variable_name' with the parameter to be displayed.

Software Support

Library Description

This library contains API for ROTARY G Click driver.

Key functions:

  • rotaryg_generic_transfer - ROTARY G data transfer function.

  • rotaryg_turn_on_led_by_position - Function turn on led by position

  • rotaryg_button_push - Function return 1 if button is pushed and return 0 if not

Open Source

Code example

The complete application code and a ready-to-use project are available through the NECTO Studio Package Manager for direct installation in the NECTO Studio. The application code can also be found on the MIKROE GitHub account.

/*!
 * @file main.c
 * @brief Rotary G Click example
 *
 * # Description
 * The demo application controls led on Click with rotary on board.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes SPI driver, set initial states, 
 * set RST logic high and performs device configuration.
 *
 * ## Application Task
 * Show functionality of Rotary G Click, rotating and turn on/off led's,
 * using the SPI interface.
 *
 * @note
 * In orther to use all of the Clicks functionality, pull down INT pin.
 *
 * @author Stefan Ilic
 *
 */

#include "board.h"
#include "log.h"
#include "rotaryg.h"

static rotaryg_t rotaryg;
static log_t logger;

static uint8_t start_status;
static uint8_t old_state;
static uint8_t new_state;
static uint8_t old__rot_state;
static uint8_t new_rotate_state;
static uint8_t led_state;
static uint16_t led_data;

void application_init ( void ) {
    log_cfg_t log_cfg;  /**< Logger config object. */
    rotaryg_cfg_t rotaryg_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.

    rotaryg_cfg_setup( &rotaryg_cfg );
    ROTARYG_MAP_MIKROBUS( rotaryg_cfg, MIKROBUS_1 );
    err_t init_flag  = rotaryg_init( &rotaryg, &rotaryg_cfg );
    if ( init_flag == SPI_MASTER_ERROR ) {
        log_error( &logger, " Application Init Error. " );
        log_info( &logger, " Please, run program again... " );

        for ( ; ; );
    }

    log_info( &logger, " Application Task " );
    
    led_data = 0x0001;
    old_state = 0;
    new_state = 1;
    old__rot_state = 0;
    new_rotate_state = 1;
}

void application_task ( void ) {
   rotaryg_turn_on_led_by_data( &rotaryg, led_data );

   // Push button
    if ( rotaryg_button_push( &rotaryg ) ) {
        new_state = 1;
        if ( new_state == 1 && old_state == 0 ) {
            old_state = 1;
            led_state = ( led_state + 1 ) % 5;
            if ( led_state == 4 ) {
                for ( old_state = 0; old_state < 17; old_state++ ) {
                    rotaryg_turn_on_led_by_data( &rotaryg, 0xAAAA );
                    Delay_ms ( 100 );
                    rotaryg_turn_on_led_by_data( &rotaryg, 0x5555 );
                    Delay_ms ( 100 );
                }

                for ( old_state = 0; old_state < 17; old_state++ ) {
                    rotaryg_turn_on_led_by_position( &rotaryg, old_state );
                    Delay_ms ( 100 );
                }

                led_state = 0;
                led_data = rotaryg_get_led_data( led_state );
            }
            else {
                led_data = rotaryg_get_led_data( led_state );
            }
        }
    }
    else {
        old_state = 0;
    }

    //Rotate Clockwise and CounterClockwise
    if ( rotaryg_get_eca_state( &rotaryg ) == rotaryg_get_ecb_state( &rotaryg ) ) {
        old__rot_state = 0;
        start_status = rotaryg_get_eca_state( &rotaryg ) && rotaryg_get_ecb_state( &rotaryg );
    }
    else {
        new_rotate_state = 1;
        if ( new_rotate_state != old__rot_state ) {
            old__rot_state = 1;
            if ( start_status != rotaryg_get_eca_state( &rotaryg ) ) {
                led_data = ( led_data << 1 ) | ( led_data >> 15 );
            }
            else {
                led_data = ( led_data >> 1 ) | ( led_data << 15 );
            }
        }
    }
}

int main ( void ) 
{
    /* Do not remove this line or clock might not be set correctly. */
    #ifdef PREINIT_SUPPORTED
    preinit();
    #endif
    
    application_init( );
    
    for ( ; ; ) 
    {
        application_task( );
    }

    return 0;
}

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

Additional Support

Resources

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