Achieve best-in-class non-volatile memory with long data retention using MR25H256 and STM32L4R9AI
Dive into the world of MRAM
Published Sep 13, 2023
Click board™
MRAM Click
Dev. board
Discovery kit with STM32L4R9AI MCU
Compiler
NECTO Studio
MCU
STM32L4R9AI
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.
Features overview
Development board
Discovery kit with STM32L4R9AI MCU is a complete demonstration and development platform for the STMicroelectronics Arm® Cortex®-M4 core-based STM32L4R9AI microcontroller. Leveraging the innovative ultra-low-power oriented features, 640 Kbytes of embedded RAM, graphics performance (Chrom-ART Accelerator™), and DSISM controller offered by the STM32L4R9AI, the 32L4R9IDISCOVERY kit enables users to easily prototype applications with state-of-the-art energy efficiency, as well as providing stunning audio and graphics rendering with direct support for an AMOLED DSI round display. For even more user friendliness, the on-board ST-LINK/V2-1 debugger provides out-of-the-box programming and
debugging capabilities. The STM32L4R9AI microcontroller features four I2Cs, five USARTs, one ULP UART, three SPIs, two SAIs, one SDIO, one USB 2.0 full-speed OTG, two CANs, one FMC parallel synchronous interface, one 12 bit ADC, one 12-bit DAC, two ULP analog comparators, two op-amps, one two data-lane DSI display, one digital filter for sigma-delta modulation and SWP interface, two Octo-SPI interfaces, an 8- to 14-bit camera interface, one touch-sensing controller interface, JTAG, and SWD debugging support. This Discovery board offers everything users need to get started quickly and develop applications easily. The hardware features on the board help to evaluate the following peripherals: USB OTG FS, microSD™
card, 8-bit camera interface, 16-Mbit PSRAM, PMOD, and STMod+ connectors, IDD measurement, full-duplex I2S with an audio codec and stereo headset jack including an analog microphone, DFSDM with a pair of MEMS digital microphones on board, 512-Mbit Octo-SPI Flash memory device, I2C extension connector, 1.2" AMOLED display using a one data-lane DSI interface with a capacitive touch panel. The ARDUINO® compatible connectors expand the functionality with a wide choice of specialized shields. The integrated ST-LINK/V2-1 provides an embedded in-circuit debugger and programmer for the STM32 MCU.
Microcontroller Overview
MCU Card / MCU
Architecture
ARM Cortex-M4
MCU Memory (KB)
2048
Silicon Vendor
STMicroelectronics
Pin count
169
RAM (Bytes)
655360
Used MCU Pins
mikroBUS™ mapper
Take a closer look
Click board™ Schematic
Step by step
Project assembly
Start by selecting your development board and Click board™. Begin with the Discovery kit with STM32L4R9AI MCU as your development board.
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 MRAM Click driver.
Key functions:
mram_write_data_bytes- Function writes n bytes of data from the buffermram_read_data_bytes- Function reads n bytes of data and saves it in buffermram_enable_write_protect- Function enables or disables write protect.
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
* \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 10 bytes of buffer data in memory with start address 0x0001. Then reads
* 10 bytes from memory with start address 0x0001 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 ( 1000 );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
}
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
