Intermediate
30 min
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Achieve best-in-class non-volatile memory with long data retention using MR25H256 and PIC24FV16KA302

Dive into the world of MRAM

MRAM Click with EasyPIC v8 for PIC24/dsPIC33

Published Sep 13, 2023

Click board™

MRAM Click

Development board

EasyPIC v8 for PIC24/dsPIC33

Compiler

NECTO Studio

MCU

PIC24FV16KA302

Trust MRAM as your data's guardian. Our solution offers persistent memory with rapid read and write capabilities, ensuring data integrity and fast access for applications where reliability is paramount.

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Hardware Overview

How does it work?

MRAM Click is based on the MR25H256, a 256 kilobits serial SPI MRAM memory module from Everspin company. This module contains 262,144 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 MR25H256 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 MR25H256 IC is routed to the INT 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 MR25H256 IC is pulled to a HIGH logic level by an onboard pull-up resistor. The #WP pin of the MR25H256 IC is routed to the INT 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 moduke, such as read and write commands and the status register of the MR25H256 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 MRAM 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 MRAM click. Their usage is demonstrated in the included example application which can be used as a reference for further development. The device should wait for the system voltage to become stable before the writing is attempted. 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.

MRAM Click top side image
MRAM Click bottom side image

Features overview

Development board

EasyPIC v8 for PIC24/dsPIC33 is a development board specially designed for the needs of rapid development of embedded applications. It supports a wide range of 16-bit PIC24/dsPIC33 microcontrollers from Microchip and has a broad set of unique functions, such as the first-ever embedded debugger/programmer. 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, EasyPIC v8 for PIC24/dsPIC33 provides a fluid and immersive working experience, allowing access anywhere and under any circumstances. Each part of the EasyPIC

v8 for PIC24/dsPIC33 development board contains the components necessary for the most efficient operation of the same board. In addition to the advanced integrated CODEGRIP programmer/debugger module, which offers many valuable programming/debugging options and seamless integration with the Mikroe software environment, the board 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 HOST/DEVICE, USB-UART, CAN, and LIN are also

included, including the well-established mikroBUS™ standard, two display options (graphical and character-based LCD), and several different DIP sockets. These sockets cover a wide range of 16-bit PIC24/dsPIC33 MCUs, from the smallest PIC24/dsPIC33 MCUs with only 14 up to 28 pins. EasyPIC v8 for PIC24/dsPIC33 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.

EasyPIC v8 for PIC24/dsPIC33 horizontal image

Microcontroller Overview

MCU Card / MCU

default

Architecture

dsPIC

MCU Memory (KB)

16

Silicon Vendor

Microchip

Pin count

28

RAM (Bytes)

2048

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
Write Protect
RB4
RST
SPI Chip Select
RA4
CS
SPI Clock
RB7
SCK
SPI Data OUT
RB9
MISO
SPI Data IN
RB8
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
NC
NC
PWM
Data Transfer Pause
RB7
INT
NC
NC
TX
NC
NC
RX
NC
NC
SCL
NC
NC
SDA
NC
NC
5V
Ground
GND
GND
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Take a closer look

Schematic

MRAM Click Schematic schematic

Step by step

Project assembly

EasyPIC v8 for PIC24/dsPIC33 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the EasyPIC v8 for PIC24/dsPIC33 as your development board.

EasyPIC v8 for PIC24/dsPIC33 front image hardware assembly
Buck 22 Click front image hardware assembly
MCU DIP 28 hardware assembly
EasyPIC PIC24/dsPIC33 v8 DIP 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 DIP 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 MRAM Click driver.

Key functions:

  • mram_write_data_bytes - Function writes n bytes of data from the buffer

  • mram_read_data_bytes - Function reads n bytes of data and saves it in buffer

  • mram_enable_write_protect - Function enables or disables write protect.

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 MRAM Click example
 * 
 * # Description
 * This example writes and reads from the Mram Click and displays it on the terminal.
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Initializes click driver.
 * 
 * ## Application Task  
 * Writes 6 bytes of buffer data in memory with start address 0x0000. Then reads
 * 3 bytes from memory with start address 0x0002 and shows result on USB UART.
 * 
 * 
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "mram.h"

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

static mram_t mram;
static log_t logger;

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

void application_init ( void )
{
    log_cfg_t log_cfg;
    mram_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.

    mram_cfg_setup( &cfg );
    MRAM_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    mram_init( &mram, &cfg );
    mram_default_cfg( &mram );
    
}

void application_task ( void )
{
    uint8_t number_bytes_write;
    uint8_t number_bytes_read;
    uint16_t i;
    uint8_t data_write[ 10 ] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
    uint8_t data_read[ 20 ] = { 0 };
    
    number_bytes_write = 10;
    number_bytes_read = 10;

    log_printf( &logger, " Data written!\r\n" );
    mram_write_data_bytes ( &mram, 0x0001, data_write, number_bytes_write );
    
    log_printf( &logger, " Read data:\r\n" );
    mram_read_data_bytes ( &mram, 0x0001, data_read, number_bytes_read );
    
    for ( i = 0; i < number_bytes_read; i++ )
    {
        log_printf( &logger, "%d ", ( uint16_t )data_read[ i ] );
    }
    
    log_printf( &logger, "\n" );

    Delay_ms( 3000 );
}

void main ( void )
{
    application_init( );

    for ( ; ; )
    {
        application_task( );
    }
}

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

Additional Support

Resources