Redefine your SPI's signal level shifting experience with STM32L496AG

Seamless SPI signals logic level conversion

LLC-SPI Click with Discovery kit with STM32L496AG MCU

Published Jul 22, 2025

Click board™

LLC-SPI Click

Dev. board

Discovery kit with STM32L496AG MCU

Compiler

NECTO Studio

MCU

STM32L496AG

From concept to implementation, our SPI-signal logic level converter simplifies complex voltage conversion challenges, providing the precision, adaptability, and control you need to achieve exceptional results in your project

Hardware Overview

How does it work?

LLC SPI Click does not use any integrated circuit, as already mentioned. With ICs avoided completely, there are some benefits gained: the overall cost of the LLC circuit is greatly reduced, a more robust MOSFET solution reduces the failure rate, and when powered off, both the low voltage and the high voltage sides are isolated from one another (by non-conductive MOSFETs). This type of circuit is sometimes referred to as a level shifting or level translating circuit and it is often necessary when one SPI device (typically a sensor IC) uses different logic voltage levels for the communication than the controller device, which

is a microcontroller (MCU) in most cases. The conversion of this circuitry is bi-directional, which makes it suitable to be used with the SPI communication protocol. The SPI protocol was first introduced by Motorola, in the '80s. The circuit is divided into low-side and high-side sections for future reference, however, both up-shifting, and down-shifting of the voltage level is possible. The mechanisms are slightly different, so each will be explained separately. The reference voltage for the high-side can be selected by using the SMD jumper labeled as VCC SEL. The pull-up voltage for the high-side can be selected from the

mikroBUS™ power rails, so it can be either 3.3V or 5V. For the low-side, an arbitrary reference voltage can be applied to the VSL pin of the J1 header, respecting the maximum voltage rating, as well as the condition mentioned above. J1 is the standard, 2.54mm pin-header. The low-side SPI related pins are also routed to the J1 header, allowing an external device to be connected (using the standard wire-jumpers). As already mentioned, the low-side can actually use higher voltage levels than the master, but in most usage scenarios, it will be lower than the master, thus the terminology used in the text above.

Features overview

Development board

The 32L496GDISCOVERY Discovery kit serves as a comprehensive demonstration and development platform for the STM32L496AG microcontroller, featuring an Arm® Cortex®-M4 core. Designed for applications that demand a balance of high performance, advanced graphics, and ultra-low power consumption, this kit enables seamless prototyping for a wide range of embedded solutions. With its innovative energy-efficient

architecture, the STM32L496AG integrates extended RAM and the Chrom-ART Accelerator, enhancing graphics performance while maintaining low power consumption. This makes the kit particularly well-suited for applications involving audio processing, graphical user interfaces, and real-time data acquisition, where energy efficiency is a key requirement. For ease of development, the board includes an onboard ST-LINK/V2-1

debugger/programmer, providing a seamless out-of-the-box experience for loading, debugging, and testing applications without requiring additional hardware. The combination of low power features, enhanced memory capabilities, and built-in debugging tools makes the 32L496GDISCOVERY kit an ideal choice for prototyping advanced embedded systems with state-of-the-art energy efficiency.

Discovery kit with STM32L496AG MCU double side image

Microcontroller Overview

MCU Card / MCU

Architecture

ARM Cortex-M4

MCU Memory (KB)

1024

Silicon Vendor

STMicroelectronics

Pin count

169

RAM (Bytes)

327680

Used MCU Pins

mikroBUS™ mapper

RST

SPI Chip Select

PG11

SPI Clock

PI1

SCK

SPI Data OUT

PD3

MISO

SPI Data IN

PI3

MOSI

Power Supply

3.3V

Ground

GND

PWM

INT

SCL

SDA

Power Supply

Ground

GND

Take a closer look

Click board™ Schematic

Step by step

Project assembly

Discovery kit with STM32H750XB MCU front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Discovery kit with STM32L496AG MCU as your development board.

Thermo 21 Click front image hardware assembly

Thermo 21 Click complete accessories setup image hardware assembly

Board mapper by product7 hardware assembly

Discovery kit with STM32H750XB MCU NECTO MCU Selection Step hardware assembly

Necto No Display image step 8 hardware assembly

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 LLC-SPI Click driver.

Key functions:

llcspi_generic_write - LLC SPI write
llcspi_generic_read - LLC SPI read
llcspi_generic_transfer - LLC SPI transfer

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 llcspi Click example
 * 
 * # Description
 * This application is converter for logic signals.
 *
 * The demo application is composed of two sections : 
 * 
 * ## Application Init 
 * Initialization device init
 * 
 * ## Application Task  
 * Counter passes through the loop and logs the value of the counter on the bargraph display
 * 
 * *note:* 
 * Connection between BarGraph and LLC-SPI is made through SPI interface.
 * You can connect a BarGraph Click to LLC-SPI Click with the wires to make connection between Click boards.
 * We use the BarGraph Click to demonstrate the functions of the LLC-SPI Click.
 * 
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "llcspi.h"

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

static llcspi_t llcspi;
static log_t logger;

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

void application_init ( void )
{
    log_cfg_t log_cfg;
    llcspi_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.

    llcspi_cfg_setup( &cfg );
    LLCSPI_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    llcspi_init( &llcspi, &cfg );
}

void application_task ( void )
{
    uint16_t convert;
    uint8_t tmp[ 2 ];
    uint8_t cnt;

    // BarGraph display
    for ( cnt = 0; cnt <= 10; cnt++ )
    {
        convert  = ( uint16_t ) ( ( 1 << cnt ) - 1 );
        tmp[ 1 ] = ( convert & 0x00FF );
        tmp[ 0 ] = ( convert & 0xFF00 ) >> 8;
    
        llcspi_generic_write( &llcspi, tmp, 2 );
        
        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