30 min

Maximize data storage capacity with AT24CM02 and STM32F429ZI

4 million reasons to choose EEPROM!

Dual EE Click with Fusion for ARM v8

Published Aug 23, 2023

Click board™

Dual EE Click

Development board

Fusion for ARM v8


NECTO Studio



Amplify your data storage prowess through our state-of-the-art solution, showcasing dual EEPROM memory with an impressive 4Mb capacity



Hardware Overview

How does it work?

Dual EE Click is based on two AT24CM02, an I2C serial EEPROM from Microchip. This means the ICs can have a different I2C address so that users can choose which one they would like to use at a particular time. This is achieved by wiring the I2C address selection lines from one of the ICs to the VCC while the other IC is wired to the GND. Given this feature, it is important to note that this click board has 4MB of memory. This Click board™ uses the I2C communication protocol. Therefore, the host MCU initiates every data transaction event, transmitting the I2C START condition, followed by the AT24CM02 device ID byte. Upon receiving the device ID byte, the AT24CM02 IC expects two more address bytes, completing the 18-bit address word. The EEPROM density is usually expressed in bits, so exactly 2.097.152 bits are organized in units or words of 8 bits, which gives 262.144 bytes of data memory. Furthermore, the EEPROM is

organized into so-called pages. One page holds 256 bytes, and there are 1024 pages (1024 pages x 256 bytes = 262.144 bytes total). Given that this click contains two EEPROM Ics, this Click board™ has twice as much memory, equaling 4 MB. Having insight into how the memory cells are organized is important for Write and Erase operations. The I2C pins are routed to the mikroBUS™, making communication easy and straightforward. Both 100KHz and 400KHz transfer speeds are supported by the AT24CM02 IC and the 1MHz Fast Mode Plus (FM+) I2C communication for the MCUs with I2C modules that can support that speed. One of the key features of the AT24CM02 IC is the Error Detection and Correction scheme (EDC), which allows error correction by utilizing six additional bits internally assigned to a group of four bytes. This protection scheme can correct some bit errors, staying transparent to the end

user. The bit comparison and error correction are done internally. The Dual EE Click board™ offers a selection between 3.3V and 5V operation, with the onboard SMD jumper labeled PWR SEL. This allows both 3.3V and 5V MCUs to be interfaced with this Click board™. The attached device datasheet contains an in-depth explanation of all the mentioned functions. However, Mikroe provides a library with functions that make the final code clean and readable, simplifying working with this device. These functions internally employ the aforementioned communication mechanism and expose only a simple and clean interface to the user. The provided example code demonstrates the functionality of these functions. It can be used as a reference point for custom development.

Dual EE Click top side image
Dual EE Click bottom side image

Features overview

Development board

Fusion for ARM 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 ARM® Cortex®-M based MCUs 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 ARM v8 provides a fluid and immersive working experience, allowing access anywhere and under any

circumstances at any time. Each part of the Fusion for ARM 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 ARM 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 ARM 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
I2C Clock
I2C Data
Power Supply

Take a closer look


Dual EE 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 ARM 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 Dual EE Click driver.

Key functions:

  • dualee_read - Generic write data function

  • dualee_write - Generic write data 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 DualEE Click example
 * # Description
 * This application writes data in memory and reads data from memory
 * The demo application is composed of two sections :
 * ## Application Init 
 * Initializes device init
 * ## Application Task  
 * Reads your command and then execute it
 * \author MikroE Team
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "dualee.h"

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

static dualee_t dualee;
static log_t logger;

static uint32_t page_address = 0x00000000;
static uint8_t write_data[ 7 ] = { 'M', 'i', 'k', 'r', 'o', 'E', 0 };

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

void application_init ( void )
    log_cfg_t log_cfg;
    dualee_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_info( &logger, "---- Application Init ----" );

    //  Click initialization.

    dualee_cfg_setup( &cfg );
    dualee_init( &dualee, &cfg );

    log_printf( &logger, "*********** APPLICATION INIT ***********\r\n" );
    Delay_ms( 100 );

void application_task ( )
    uint8_t write_dual;
    uint8_t read_dual;
    char demo_text[ 255 ];

    log_printf( &logger, "Writing data [MikroE]....\r\n" );
    write_dual = dualee_write( &dualee, page_address, write_data, 7 );
    if ( write_dual == DUALEE_ERROR_RW )
        log_printf( &logger, "Error writing data!!!\r\n" );
        Delay_ms( 1000 );
    Delay_ms( 100 );

    log_printf( &logger, "Reading data...\r\n" );
    read_dual = dualee_read( &dualee, page_address, demo_text, 7 );

    if ( read_dual == 0 )
        log_printf( &logger, "Error reading data!!!\r\n" );
        Delay_ms( 1000 );
    Delay_ms( 100 );
    log_printf( &logger, "Data from read page is: %s \r\n", demo_text );
    log_printf( &logger, "__________________________________\r\n" );
    Delay_ms( 1000 );

void main ( void )
    application_init( );

    for ( ; ; )
        application_task( );

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

Additional Support