Beginner
10 min

Achieve safety isolation from high voltage with ISOM8710 and STM32L073RZ

High voltage, low worries

Opto 7 Click with Nucleo-64 with STM32L073RZ MCU

Published Feb 26, 2024

Click board™

Opto 7 Click

Dev.Board

Nucleo-64 with STM32L073RZ MCU

Compiler

NECTO Studio

MCU

STM32L073RZ

Safety shield that you can add to electronic systems, especially in applications like power supplies, electricity meters, motor drives, and automation systems

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Hardware Overview

How does it work?

Opto 7 Click is based on two ISOM8710s, high-speed single-channel opto-emulators from Texas Instruments. It can transmit data rates of up to 25Mbps and output 3.3V and 5V signals with a CMOS-compatible output. Compared to an optocoupler, the ISOM7810 has a high common mode transient immunity, low propagation delay, small pulse with distortion, low power consumption, and more. Opto 7 Click is equipped with two of these opto-emulators for receiving and transmitting

data. The external power supply can be connected to a VCC2 terminal and must be 3.3V or 5V. The three-pin terminal connects input and output data lines along with the common ground. Opto 7 Click can use general-purpose IO to communicate with the host MCU over the GP1 and GP2 pins. It can also be used for a standard UART communication isolation with commonly used UART RX and TX pins. The selection can be made over the OUT SEL and IN SEL jumpers. Both should be in a proper

position for the communication to work. 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.

Opto 7 Click hardware overview image

Features overview

Development board

Nucleo-64 with STM32L073RZ 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 STM32L073RZ MCU double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

ARM Cortex-M0

MCU Memory (KB)

192

Silicon Vendor

STMicroelectronics

Pin count

64

RAM (Bytes)

20480

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

NC
NC
AN
NC
NC
RST
ID COMM
PB12
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
General-Purpose I/O
PC8
PWM
General-Purpose I/O
PC14
INT
UART TX
PA2
TX
UART RX
PA3
RX
NC
NC
SCL
NC
NC
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Schematic

Opto 7 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 STM32L073RZ 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

After loading the code example, pressing the "DEBUG" button builds and programs it on the selected setup.

Application Output Step 1

After programming is completed, a header with buttons for various actions available in the IDE appears. By clicking the green "PLAY "button, we start reading the results achieved with Click board™.

Application Output Step 3

Upon completion of programming, the Application Output tab is automatically opened, where the achieved result can be read. In case of an inability to perform the Debug function, check if a proper connection between the MCU used by the setup and the CODEGRIP programmer has been established. A detailed explanation of the CODEGRIP-board connection can be found in the CODEGRIP User Manual. Please find it in the RESOURCES section.

Application Output Step 4

Software Support

Library Description

This library contains API for Opto 7 Click driver.

Key functions:

  • opto7_generic_write - Opto 7 data writing function.

  • opto7_set_gp1_pin - Opto 7 set GP1 pin function.

  • opto7_get_gp2_pin - Opto 7 get GP2 pin 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 Opto 7 Click Example.
 *
 * # Description
 * This example demonstrates the use of Opto 7 click board by processing
 * the incoming data and displaying them on the USB UART.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initialization of UART LOG and GPIO pin, and UART drivers.
 *
 * ## Application Task
 * This example is made of two parts:
 * GPIO Example - The output pin is toggled every 5 seconds and input pin state is being tracked.
 * UART Example - Device assigned as transmitter is sending message and receiver is reading it and displaying it on USB UART.
 * 
 * ## Additional Function
 * - static void opto7_clear_app_buf ( void )
 * - static void opto7_log_app_buf ( void )
 * - static err_t opto7_process ( opto7_t *ctx )
 * 
 * @author Stefan Ilic
 *
 */

#include "board.h"
#include "log.h"
#include "opto7.h"

// Example selection macros
#define EXAMPLE_GPIO                1               // Example of using GPIO
#define EXAMPLE_UART                2               // Example of using UART
#define DEMO_EXAMPLE                EXAMPLE_GPIO    // Example selection macro

// Macros for UART example
#define TRANSMITTER                 // Comment out this line to place device into receiver mode
#define TX_MESSAGE                  "Opto 7 Click Example \r\n"

// Application buffer size
#define APP_BUFFER_SIZE             500
#define PROCESS_BUFFER_SIZE         200

static opto7_t opto7;
static log_t logger;


static uint8_t app_buf[ APP_BUFFER_SIZE ] = { 0 };
static int32_t app_buf_len = 0;

/**
 * @brief Test clearing application buffer.
 * @details This function clears memory of application buffer and reset its length.
 * @note None.
 */
static void opto7_clear_app_buf ( void );

/**
 * @brief Test log application buffer.
 * @details This function logs data from application buffer to USB UART.
 * @note None.
 */
static void opto7_log_app_buf ( void );

/**
 * @brief Test data reading function.
 * @details This function reads data from device and concatenates data to application buffer. 
 * @param[in] ctx : Click context object.
 * See #opto7_t object definition for detailed explanation.
 * @return @li @c  0 - Read some data.
 *         @li @c -1 - Nothing is read.
 * See #err_t definition for detailed explanation.
 * @note None.
 */
static err_t opto7_process ( opto7_t *ctx );

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    opto7_cfg_t opto7_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 " );
    
    // Click initialization.
    opto7_cfg_setup( &opto7_cfg );
    OPTO7_MAP_MIKROBUS( opto7_cfg, MIKROBUS_1 );
    
#if ( DEMO_EXAMPLE == EXAMPLE_GPIO )
    opto7_drv_interface_selection( &opto7_cfg, OPTO7_DRV_SEL_GPIO );
#else
    opto7_drv_interface_selection( &opto7_cfg, OPTO7_DRV_SEL_UART );
#endif
    
    if ( UART_ERROR == opto7_init( &opto7, &opto7_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    
    log_info( &logger, " Application Task " );
}

void application_task ( void ) 
{
#if ( DEMO_EXAMPLE == EXAMPLE_GPIO )
    log_printf( &logger, " GP1 pin state HIGH \r\n" );
    opto7_set_gp1_pin( &opto7, OPTO7_PIN_STATE_HIGH );
     if ( OPTO7_PIN_STATE_HIGH == opto7_get_gp2_pin( &opto7 ) )
    {
        log_printf( &logger, " GP2 pin state HIGH \r\n" );
    }
    else
    {
        log_printf( &logger, " GP2 pin state LOW \r\n" );
    }
    log_printf( &logger, "- - - - - - - - - - - -\r\n" );
    Delay_ms( 5000 );
    
    log_printf( &logger, " GP1 pin state LOW \r\n" );
    opto7_set_gp1_pin( &opto7, OPTO7_PIN_STATE_LOW );
    if ( OPTO7_PIN_STATE_HIGH == opto7_get_gp2_pin( &opto7 ) )
    {
        log_printf( &logger, " GP2 pin state HIGH \r\n" );
    }
    else
    {
        log_printf( &logger, " GP2 pin state LOW \r\n" );
    }
    log_printf( &logger, "- - - - - - - - - - - -\r\n" );
    Delay_ms( 5000 );
#else
#if defined TRANSMITTER
    log_printf( &logger, " Message sent! \r\n" );
    opto7_generic_write( &opto7, TX_MESSAGE, strlen( TX_MESSAGE ) );
    Delay_ms( 2000 );
#else
    if ( OPTO7_OK == opto7_process( &opto7 ) ) 
    {
        opto7_log_app_buf( );
        opto7_clear_app_buf( );
    }
#endif

#endif
}

void main ( void ) 
{
    application_init( );

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

static void opto7_clear_app_buf ( void ) 
{
    memset( app_buf, 0, app_buf_len );
    app_buf_len = 0;
}

static void opto7_log_app_buf ( void )
{
    for ( int32_t buf_cnt = 0; buf_cnt < app_buf_len; buf_cnt++ )
    {
        log_printf( &logger, "%c", app_buf[ buf_cnt ] );
    }
}

static err_t opto7_process ( opto7_t *ctx ) 
{
    uint8_t rx_buf[ PROCESS_BUFFER_SIZE ] = { 0 };
    int32_t overflow_bytes = 0;
    int32_t rx_cnt = 0;
    int32_t rx_size = opto7_generic_read( ctx, rx_buf, PROCESS_BUFFER_SIZE );
    if ( ( rx_size > 0 ) && ( rx_size <= APP_BUFFER_SIZE ) ) 
    {
        if ( ( app_buf_len + rx_size ) > APP_BUFFER_SIZE ) 
        {
            overflow_bytes = ( app_buf_len + rx_size ) - APP_BUFFER_SIZE;
            app_buf_len = APP_BUFFER_SIZE - rx_size;
            memmove ( app_buf, &app_buf[ overflow_bytes ], app_buf_len );
            memset ( &app_buf[ app_buf_len ], 0, overflow_bytes );
        }
        for ( rx_cnt = 0; rx_cnt < rx_size; rx_cnt++ ) 
        {
            if ( rx_buf[ rx_cnt ] ) 
            {
                app_buf[ app_buf_len++ ] = rx_buf[ rx_cnt ];
            }
        }
        return OPTO7_OK;
    }
    return OPTO7_ERROR;
}

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

Additional Support

Resources