30 min

Unlock the potential of data storage with MB85AS4MT and PIC18F86J15

ReRAM: Your gateway to speed, efficiency, and data density

ReRAM Click with UNI Clicker

Published Oct 18, 2023

Click board™

ReRAM Click

Development board

UNI Clicker


NECTO Studio



Explore how ReRAM is reshaping the memory landscape, delivering faster, more efficient data storage solutions for the modern world



Hardware Overview

How does it work?

ReRAM Click board is based on the MB85AS4MT, a 4Mb serial SPI ReRAM memory module from Fujitsu. This module contains 524.288 x 8 bits of memory that can be randomly accessed. The pinout of the used memory module is the same as most commonly used EEPROM modules so that it can directly replace it. The usual SPI lines - SO, SI, SCK and #CS pins from the MB85AS4MT IC are routed to the mikroBUS™ SPI port (MISO, MOSI, SCK and CS pins). Besides the SPI serial bus, there are two more pins routed to the mikroBUS™. The #HOLD pin of the MB85AS4MT IC is routed to the RST pin of the mikroBUS™ and it is used to hold the data transfer. When this pin is pulled to a LOW logic level, all data transfer operations are suspended. However, this function is enabled only when the device is already addressed with the CS

pin pulled to a LOW level. This allows to pause the data transfer and resume it later without the need to first address it via the CS pin, reducing the output latency that way. While the data transfer is paused, the SO pin will switch to a high impedance mode (HIGH Z) and will remain inactive. The SCK pulses are completely ignored. The #HOLD pin of the MB85AS4MT IC is pulled to a HIGH logic level by an onboard pull-up resistor. The #WP pin of the MB85AS4MT IC is routed to the PWM pin of the mikroBUS™ and it is used to prevent writes to the status register, acting as a hardware write protect pin. It is routed to the RST pin of the mikroBUS™. The logical organization of the module, such as read and write commands and the status register of the MB85AS4MT IC are the same as with most commonly used

EEPROM modules, such as the one used in EEPROM 4 click. That allows this memory module, as well as ReRAM click to replace the existing EEPROM module with not too much additional work. The provided libraries offer all the functions needed to work with the ReRAM click. Their usage is demonstrated in the included example application which can be used as a reference for further development. This Click board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. Also, it comes equipped with a library containing functions and an example code that can be used as a reference for further development.

ReRAM Click top side image
ReRAM Click bottom side image

Features overview

Development board

UNI Clicker is a compact development board designed as a complete solution that brings the flexibility of add-on Click boards™ to your favorite microcontroller, making it a perfect starter kit for implementing your ideas. It supports a wide range of microcontrollers, such as different ARM, PIC32, dsPIC, PIC, and AVR from various vendors like Microchip, ST, NXP, and TI (regardless of their number of pins), four mikroBUS™ sockets for Click board™ connectivity, a USB connector, LED indicators, buttons, a debugger/programmer connector, and two 26-pin headers for interfacing with external electronics. Thanks to innovative manufacturing technology, it allows you to build

gadgets with unique functionalities and features quickly. Each part of the UNI Clicker development kit contains the components necessary for the most efficient operation of the same board. In addition to the possibility of choosing the UNI Clicker programming method, using a third-party programmer or CODEGRIP/mikroProg connected to onboard JTAG/SWD header, the UNI Clicker board also includes a clean and regulated power supply module for the development kit. It provides two ways of board-powering; through the USB Type-C (USB-C) connector, where onboard voltage regulators provide the appropriate voltage levels to each component on the board, or using a Li-Po/Li

Ion battery via an onboard battery connector. All communication methods that mikroBUS™ itself supports are on this board (plus USB HOST/DEVICE), including the well-established mikroBUS™ socket, a standardized socket for the MCU card (SiBRAIN standard), and several user-configurable buttons and LED indicators. UNI Clicker is an integral part of the Mikroe ecosystem, allowing you to create a new application in minutes. Natively supported by Mikroe software tools, it covers many aspects of prototyping thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.

UNI clicker double image

Microcontroller Overview

MCU Card / MCU



8th Generation



MCU Memory (KB)


Silicon Vendor


Pin count


RAM (Bytes)


Used MCU Pins

mikroBUS™ mapper

Data Transfer Pause
SPI Chip Select
SPI Clock
Power Supply
Write Protect

Take a closer look


ReRAM Click Schematic schematic

Step by step

Project assembly

UNI Clicker front image hardware assembly

Start by selecting your development board and Click board™. Begin with the UNI Clicker as your development board.

UNI Clicker front image hardware assembly
Thermo 28 Click front image hardware assembly
SiBRAIN for STM32F745VG front image hardware assembly
Prog-cut hardware assembly
UNI Clicker MB 1 - upright/with-background 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
Necto image step 7 hardware assembly
Necto No Display image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Debug Image Necto Step hardware assembly

Track your results in real time

Application Output

After loading the code example, pressing the "DEBUG" button builds and programs it on the selected setup.

Application Output Step 1

After programming is completed, a header with buttons for various actions available in the IDE appears. By clicking the green "PLAY "button, we start reading the results achieved with Click board™.

Application Output Step 3

Upon completion of programming, the Application Output tab is automatically opened, where the achieved result can be read. In case of an inability to perform the Debug function, check if a proper connection between the MCU used by the setup and the CODEGRIP programmer has been established. A detailed explanation of the CODEGRIP-board connection can be found in the CODEGRIP User Manual. Please find it in the RESOURCES section.

Application Output Step 4

Software Support

Library Description

This library contains API for ReRAM Click driver.

Key functions:

  • reram_send_cmd - Command Send function

  • reram_read_status - Status Read function

  • reram_write_memory - Memory Write 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 main.c
 * \brief ReRAM Click example
 * # Description
 * This example demonstrates the use of the ReRAM Click board.
 * The demo application is composed of two sections :
 * ## Application Init
 * Initializes SPI serial interface and puts a device to the initial state.
 * Data from 0 to 255 will be written in memory block from address 0x0 to
 * address 0xFF.
 * ## Application Task
 * Reads same memory block starting from address 0x0 to address 0xFF and
 * sends memory content to USB UART, to verify memory write operation.
 * *note:*
 * Write Enable Latch is reset after the following operations:
 *  - After 'Write Disable'command recognition.
 *  - The end of writing process after 'Write Status' command recognition.
 *  - The end of writing process after 'Write Memory' command recognition.
 * Data will not be written in the protected blocks of the ReRAM array.
 *  - Upper 1/4 goes from address 0x60000 to 0x7FFFF.
 *  - Upper 1/2 goes from address 0x40000 to 0x7FFFF.
 *  - The entire ReRAM array goes from address 0x00000 to 0x7FFFF.
 * \author Nemanja Medakovic
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "reram.h"

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

static reram_t reram;
static log_t logger;

static char write_buf[  ] = "MikroE";
static char read_buf[ 10 ] = { 0 };

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

void application_init( void )
    reram_cfg_t reram_cfg;
    log_cfg_t logger_cfg;

    //  Click object initialization.
    reram_cfg_setup( &reram_cfg );
    RERAM_MAP_MIKROBUS( reram_cfg, MIKROBUS_1 );
    reram_init( &reram, &reram_cfg );

    //  Click start configuration.
    reram_default_cfg( &reram );

     * 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( logger_cfg );
    log_init( &logger, &logger_cfg );
    reram_wake_up( &reram );
    uint32_t id_data = reram_read_id( &reram );
    if ( RERAM_ID_DATA != id_data )
        log_printf( &logger, "***  ReRAM Error ID  ***\r\n" );
        for( ; ; );
        log_printf( &logger, "***  ReRAM Initialization Done  ***\r\n" );
        log_printf( &logger, "***********************************\r\n" );

    reram_send_cmd( &reram, RERAM_CMD_WREN );
    Delay_ms( 1000 );

void application_task( void )
    log_printf( &logger, "* Writing data *\r\n" );
    reram_write_memory( &reram, RERAM_MEM_ADDR_START, write_buf, 6 );
    Delay_ms( 1000 );
    reram_read_memory( &reram, RERAM_MEM_ADDR_START, read_buf, 6 );

    log_printf( &logger, "* Read data:%s\r\n", read_buf );
    Delay_ms( 2000 );

void main( void )
    application_init( );

    for ( ; ; )
        application_task( );

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

Additional Support