Intermediate
30 min

Enable long-distance data transmission with ease using LTC4332 and STM32F091RC

SPI goes the extra mile: Extending communication for industrial success

SPI Extend Click with Nucleo-64 with STM32F091RC MCU

Published Feb 26, 2024

Click board™

SPI Extend Click

Dev. board

Nucleo-64 with STM32F091RC MCU

Compiler

NECTO Studio

MCU

STM32F091RC

Uncover the simplicity and efficiency of our SPI extender solution, providing an accessible and effective means to transmit data over extended distances, transforming the way you connect and communicate

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Hardware Overview

How does it work?

SPI Extend Click is based on LTC4332, a 2MHz point-to-point SPI bus extender designed for operation in high-noise industrial environments, IC from Analog Devices. The SPI bus is extended over two twisted pairs by ±60V fault-protected differential transceivers. The LTC4332’s extended 25V common-mode voltage range allows it to bridge across different ground potentials. This Click board™ has three extended slave selects (SS1, SS2, SS3), has separate programmable SPI modes, and supports external galvanic isolation on the link. Slave select output pin SS1 is used as a standard CS pin in SPI communication, while the other two pins, SS2 and SS3, are used as GPIO output pins on the local side in terms of mikroBUS standard. To achieve the complete functionality of this Click board™, it is necessary to use crossover twisted-pair cables with RJ45 connectors, the same ones used with Ethernet devices. Alongside

its extended functionalities, this Click board™ also supports local to remote control and interrupt functions. Using an integrated high-performance differential transceiver for link communication, a local SPI master can access remote slave devices up to 1200m using differential-pair type cabling. Because of the dual functionality of the SPI Extend Click, the user needs to set the mode of operation of the Click board™, which is adjusted by setting the onboard MODE SEL switch to the appropriate position (set low for local SPI slave mode or set high for SPI master mode). The SPI Extend Click communicates with MCU using the SPI serial interface that supports SPI modes (0,0) and (1,1) only, with a maximum SPI frequency of 2 MHz. The LTC4332 provides a separate slave select pin, SSC, allowing users to access the internal control interface for configuration and monitoring. It also has an interrupt pin (INT) that acts as an

open-drain output in local mode and an input in remote mode. On the remote side, INT is an input pin that can be connected to remote SPI devices, while on the local side, INT operates as an open-drain output that can be connected to a shared local interrupt line. In addition to the mode selection, SPEED SEL jumpers select the link baud rate, and the remote SCK timing parameters, and the Link Status LED indicator is active when the device successfully establishes link communication between the local and remote sides. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. Also, this Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used as a reference for further development.

SPI Extend Click hardware overview image

Features overview

Development board

Nucleo-64 with STM32F091RC MCU offers a cost-effective and adaptable platform for developers to explore new ideas and prototype their designs. This board harnesses the versatility of the STM32 microcontroller, enabling users to select the optimal balance of performance and power consumption for their projects. It accommodates the STM32 microcontroller in the LQFP64 package and includes essential components such as a user LED, which doubles as an ARDUINO® signal, alongside user and reset push-buttons, and a 32.768kHz crystal oscillator for precise timing operations. Designed with expansion and flexibility in mind, the Nucleo-64 board features an ARDUINO® Uno V3 expansion connector and ST morpho extension pin

headers, granting complete access to the STM32's I/Os for comprehensive project integration. Power supply options are adaptable, supporting ST-LINK USB VBUS or external power sources, ensuring adaptability in various development environments. The board also has an on-board ST-LINK debugger/programmer with USB re-enumeration capability, simplifying the programming and debugging process. Moreover, the board is designed to simplify advanced development with its external SMPS for efficient Vcore logic supply, support for USB Device full speed or USB SNK/UFP full speed, and built-in cryptographic features, enhancing both the power efficiency and security of projects. Additional connectivity is

provided through dedicated connectors for external SMPS experimentation, a USB connector for the ST-LINK, and a MIPI® debug connector, expanding the possibilities for hardware interfacing and experimentation. Developers will find extensive support through comprehensive free software libraries and examples, courtesy of the STM32Cube MCU Package. This, combined with compatibility with a wide array of Integrated Development Environments (IDEs), including IAR Embedded Workbench®, MDK-ARM, and STM32CubeIDE, ensures a smooth and efficient development experience, allowing users to fully leverage the capabilities of the Nucleo-64 board in their projects.

Nucleo 64 with STM32F091RC MCU double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

ARM Cortex-M0

MCU Memory (KB)

256

Silicon Vendor

STMicroelectronics

Pin count

64

RAM (Bytes)

32768

You complete me!

Accessories

Click Shield for Nucleo-64 comes equipped with two proprietary mikroBUS™ sockets, allowing all the Click board™ devices to be interfaced with the STM32 Nucleo-64 board with no effort. This way, Mikroe allows its users to add any functionality from our ever-growing range of Click boards™, such as WiFi, GSM, GPS, Bluetooth, ZigBee, environmental sensors, LEDs, speech recognition, motor control, movement sensors, and many more. More than 1537 Click boards™, which can be stacked and integrated, are at your disposal. The STM32 Nucleo-64 boards are based on the microcontrollers in 64-pin packages, a 32-bit MCU with an ARM Cortex M4 processor operating at 84MHz, 512Kb Flash, and 96KB SRAM, divided into two regions where the top section represents the ST-Link/V2 debugger and programmer while the bottom section of the board is an actual development board. These boards are controlled and powered conveniently through a USB connection to program and efficiently debug the Nucleo-64 board out of the box, with an additional USB cable connected to the USB mini port on the board. Most of the STM32 microcontroller pins are brought to the IO pins on the left and right edge of the board, which are then connected to two existing mikroBUS™ sockets. This Click Shield also has several switches that perform functions such as selecting the logic levels of analog signals on mikroBUS™ sockets and selecting logic voltage levels of the mikroBUS™ sockets themselves. Besides, the user is offered the possibility of using any Click board™ with the help of existing bidirectional level-shifting voltage translators, regardless of whether the Click board™ operates at a 3.3V or 5V logic voltage level. Once you connect the STM32 Nucleo-64 board with our Click Shield for Nucleo-64, you can access hundreds of Click boards™, working with 3.3V or 5V logic voltage levels.

Click Shield for Nucleo-64 accessories 1 image

Used MCU Pins

mikroBUS™ mapper

Slave Select 3
PC0
AN
Slave Select 2
PC12
RST
SPI Chip Select
PB12
CS
SPI Clock
PB3
SCK
SPI Data OUT
PB4
MISO
SPI Data IN
PB5
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
Control Interface Select
PC8
PWM
Interrupt
PC14
INT
NC
NC
TX
NC
NC
RX
NC
NC
SCL
NC
NC
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

SPI Extend Click Schematic schematic

Step by step

Project assembly

Click Shield for Nucleo-64 accessories 1 image hardware assembly

Start by selecting your development board and Click board™. Begin with the Nucleo-64 with STM32F091RC MCU as your development board.

Click Shield for Nucleo-64 accessories 1 image hardware assembly
Nucleo 64 with STM32F401RE MCU front image hardware assembly
LTE IoT 5 Click front image hardware assembly
Prog-cut hardware assembly
LTE IoT 5 Click complete accessories setup image hardware assembly
Nucleo-64 with STM32XXX MCU Access MB 1 Mini B Conn - upright/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
Clicker 4 for STM32F4 HA MCU Step 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

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 SPI Extend Click driver.

Key functions:

  • spiextend_get_config - Function get configuration of the LTC4332 SPI Extender Over Rugged Differential Link on the SPI Extend Click

  • spiextend_set_config - Function set configuration of the LTC4332 SPI Extender Over Rugged Differential Link on the SPI Extend Click

  • spiextend_get_status - Function get status of the LTC4332 SPI Extender Over Rugged Differential Link on the SPI Extend Click

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 main.c
 * @brief SPIExtend Click example
 *
 * # Description
 *  In this example, if the connection is established, we read Accel axis of the connected
 * Accel 14 Click boards to the SPI Extend Click ( Remote Mode ) which is connected by a LAN cable to 
 * SPI Extend Click ( Local Mode ) placed in the mikroBUS 1. Results are being sent to the Usart Terminal where you can track their
 * changes. All data logs write on USB uart changes for every 1 sec.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes SPI, sets INT pin as input and AN, RST, CS nad PWM pins as outputs and begins to write log.
 * Also, initialization driver enables - SPI, set default configuration of the Accel 14 Click
 * connected to the SPI Extend Click ( Remote Mode ).
 *
 * ## Application Task
 * If the Click is connected properly then the status becomes active and the X-axis coordinate is printed first on the UART terminal, 
 * then Y and finally Z. After 1s the process is repeated. 
 * In case an error has occurred, printed "LINK is not established" on UART Terminal.
 * 
 * Additional Functions :
 *  - void spiextend_accel14_get_axis ( uint8_t axis_out_reg ) - SPI Extend reading axis function.
 *  - void spiextend_display_status ( uint8_t check_status ) - SPI Extend check display status function.
 *
 * @author Jelena Milosavljevic
 *
 */

#include "board.h"
#include "log.h"
#include "spiextend.h"

static spiextend_t spiextend;
static log_t logger;

static int16_t axis;
spiextend_status_data_t spiextend_status;

/**
 * @brief SPI Extend reading axis function.
 * @details This function is used for reading axis.
 * @param[in] axis_out_reg : Data from the register.
 * @return Nothing. 
 */
void spiextend_accel14_get_axis ( uint8_t axis_out_reg );

/**
 * @brief SPI Extend check display status function.
 * @details This function is used for check display status.
 * @param[in] check_status : Display data.
 * @return Nothing.
 */
void spiextend_display_status ( uint8_t check_status );

void application_init ( void ) {
    
    log_cfg_t log_cfg;                /**< Logger config object. */
    spiextend_cfg_t spiextend_cfg;    /**< Click config object. */

    /** 
     * 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 \r\n" );

    // Click initialization.

    spiextend_cfg_setup( &spiextend_cfg );
    SPIEXTEND_MAP_MIKROBUS( spiextend_cfg, MIKROBUS_1 );
    err_t init_flag  = spiextend_init( &spiextend, &spiextend_cfg );
    if ( SPI_MASTER_ERROR == init_flag ) {
       
        log_error( &logger, " Application Init Error. \r\n" );
        log_info( &logger, " Please, run program again... \r\n" );

        for ( ; ; );
    }
    spiextend_default_cfg( &spiextend);
    log_printf( &logger, "---------------------\r\n" );
    log_printf( &logger, "   SPI Extend Click  \r\n" );
    log_printf( &logger, "---------------------\r\n" );
    Delay_ms ( 100 );
    
    spiextend_get_status( &spiextend, &spiextend_status );
    log_printf( &logger, " LINK        : " ); 
    
    spiextend_display_status( spiextend_status.nlink );
    log_printf( &logger, " INT         : " );
    
    spiextend_display_status( spiextend_status.nint );
    log_printf( &logger, " Remote INT  : " );
    spiextend_display_status( spiextend_status.rmt_nint );
    
    log_printf( &logger, " Speed Index : %d\r\n", ( uint16_t ) spiextend_status.speed_idx );
    log_printf( &logger, "---------------------\r\n" );
    Delay_ms ( 100 );
    
    log_printf( &logger, "  >>> Accel 14 <<<   \r\n" );
    log_printf( &logger, " Set default config. \r\n" );
    spiextend_rmt_write ( &spiextend, SPIEXTEND_ACCEL14_REG_CTRL1_XL | SPIEXTEND_ACCEL14_SPI_WRITE,     
                                      SPIEXTEND_ACCEL14_CTRL1_XL_POWER_UP | 
                                      SPIEXTEND_ACCEL14_CTRL1_XL_HIGH_RES_FS | 
                                      SPIEXTEND_ACCEL14_CTRL1_XL_GSEL_4G, 
                          SPIEXTEND_SLAVE_SELECT_SS1 );
    Delay_ms ( 100 );
    
    spiextend_rmt_write ( &spiextend, SPIEXTEND_ACCEL14_REG_CTRL3_C | SPIEXTEND_ACCEL14_SPI_WRITE, 
                                      SPIEXTEND_ACCEL14_CTRL3_C_BOOT_NORMAL | 
                                      SPIEXTEND_ACCEL14_CTRL3_C_BDU_READ_UPDATE | 
                                      SPIEXTEND_ACCEL14_CTRL3_C_INT_ACTIVE_HIGH | 
                                      SPIEXTEND_ACCEL14_CTRL3_C_PP_OD_PUSH_PULL | 
                                      SPIEXTEND_ACCEL14_CTRL3_C_SIM_SPI_4_WIRE | 
                                      SPIEXTEND_ACCEL14_CTRL3_C_IF_INC_ENABLE | 
                                      SPIEXTEND_ACCEL14_CTRL3_C_SW_RESET_DIS, 
                                      SPIEXTEND_SLAVE_SELECT_SS1 );
    Delay_ms ( 100 );
    
    log_printf( &logger, "---------------------\r\n" );
    log_printf( &logger, "  Acceleration data: \r\n" );
    log_printf( &logger, "---------------------\r\n" );
    Delay_ms ( 100 );
    
    log_info( &logger, " Application Task \r\n" );
}

void application_task ( void ) {
    
    //  Task implementation.
    
    spiextend_get_status( &spiextend, &spiextend_status );
    
    if ( spiextend_status.nlink == SPIEXTEND_STATUS_ACTIVE ) {
        
        spiextend_accel14_get_axis( SPIEXTEND_ACCEL14_REG_OUTX_L_A );
        Delay_ms ( 10 );
        log_printf( &logger, "  Accel X : %d \r\n", axis );
        
        spiextend_accel14_get_axis( SPIEXTEND_ACCEL14_REG_OUTY_L_A );
        Delay_ms ( 10 );
        log_printf( &logger, "  Accel Y : %d \r\n", axis );

        spiextend_accel14_get_axis( SPIEXTEND_ACCEL14_REG_OUTZ_L_A );
        Delay_ms ( 10 );
        log_printf( &logger, "  Accel Z : %d \r\n", axis );

        log_printf( &logger, "---------------------\r\n" );
        Delay_ms ( 1000 );
    }
    else {
        
        log_printf( &logger, " LINK not established\r\n" );
        log_printf( &logger, "---------------------\r\n" );
        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;
}

void spiextend_accel14_get_axis ( uint8_t axis_out_reg ) {
  
    uint16_t rx_val;
    uint8_t lbs;
    uint8_t mbs; 
    
    lbs = spiextend_rmt_read( &spiextend, axis_out_reg| SPIEXTEND_ACCEL14_SPI_READ, 
                                                        SPIEXTEND_SLAVE_SELECT_SS1 );

    axis_out_reg++;
    mbs = spiextend_rmt_read( &spiextend, axis_out_reg | SPIEXTEND_ACCEL14_SPI_READ,    
                                                         SPIEXTEND_SLAVE_SELECT_SS1 );
    rx_val = mbs;
    rx_val <<= 8;
    rx_val |= lbs;

    axis = ( int16_t ) rx_val;
}

void spiextend_display_status ( uint8_t check_status ) {
    
    if ( check_status == SPIEXTEND_STATUS_ACTIVE ) {
       log_printf( &logger, " ON \r\n" );
    } else {
        log_printf( &logger, " OFF \r\n" );
    }
}

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

Additional Support

Resources

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