30 min

Unlock the potential of data storage with MB85AS4MT and PIC18F57K42

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

ReRAM Click with UNI-DS v8

Published Oct 18, 2023

Click board™

ReRAM Click

Dev Board



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-DS 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 STM32, Kinetis, TIVA, CEC, MSP, PIC, dsPIC, PIC32, and AVR 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, UNI-DS v8 provides a fluid and immersive working experience, allowing access anywhere and under any

circumstances at any time. Each part of the UNI-DS 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. UNI-DS 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.

UNI-DS v8 horizontal 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

Fusion for PIC v8 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the UNI-DS 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 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