Intermediate
30 min

Achieve stable connection between high-voltage components and low-voltage equipment using TLP2770 and STM32F031K6

Optocouplers: Where light and data high-five

Opto 2 Click with Nucleo 32 with STM32F031K6 MCU

Published Oct 01, 2024

Click board™

Opto 2 Click

Dev. board

Nucleo 32 with STM32F031K6 MCU

Compiler

NECTO Studio

MCU

STM32F031K6

Safeguard delicate signals from potential harm, such as electrical noise or voltage fluctuations, ensuring they reach their destination intact and unaltered.

A

A

Hardware Overview

How does it work?

Opto 2 Click is based on four TLP2770, 20Mbps low-power optocouplers from Toshiba Semiconductor. These are fast optocouplers, with their output stages shielded against EMI, allowing them to work on higher speeds, providing common-mode transient immunity of ±20 kV/μs. The internal LED elements are driven with 4mA for 5V operation or 2.6mA for 3.3V operation. The input stages are also equipped with (Schottky) diodes, which prevents inverse polarization of the LED elements and thus, a permanent damage that might occur in that case. The working principle of the optocouplers is quite simple: A photo-emitting element - usually a LED, is encapsulated inside the die along with the photo-sensitive element, which can be a photo-sensitive transistor or a photo-diode. LEDs and photo-sensing elements are galvanically isolated, making the input and output electrical networks completely independent of each other. When the LED is biased, it emits light which in return causes the current to flow through

the photo-sensitive element. In these particular optocouplers, the output stage is additionally conditioned by a Schmitt trigger and it drives the output transistors which form a totem pole output stage. Having a totem pole output configuration allows the output stage to both sink and source current. The optocoupler inputs - the anodes (labeled as A) and cathodes (labeled as C) of the internal optocoupler LEDs, are routed to the screw terminals, which allow connection the external electrical circuit, used to trigger an event on the isolated MCU. The electrical potential between the anode and the cathode input of each optocoupler element should stay within the range between 3.3V and 5V. The optocoupler outputs are routed to the mikroBUS™ The mikroBUS™ pins INT, CS, RST, and AN, are routed to the optocoupler outputs 1, 2, 3, and 4, respectively, and are labeled as IN1, IN2, IN3, and IN4. As already mentioned, the output stages are conditioned with the Schmitt trigger circuit, reducing the input noise sensitivity

and false triggering. The Faraday shield protects the output stages against EMI and provides common-mode transient immunity of ±20 kV/μs. Although these mikroBUS™ pins are labeled as IN1 to IN4, they are actually outputs from the optocouplers, and it is highly recommended to use them as the INPUT pins on the host MCU. The Click board™ is equipped with an SMD jumper labeled as LOGIC, which allows selection of the voltage, applied to the optocoupler output stage. This voltage effectively determines the logic voltage level for the MCU pins. It can be selected between 3.3V and 5V, allowing this Click board™ to be interfaced with both 3.3V and 5V MCUs. The provided library offers functions that simplify and speed up the application development. The included example application demonstrates their use. This application can be used as a reference for custom projects.

Opto 2 Click top side image
Opto 2 Click bottom side image

Features overview

Development board

Nucleo 32 with STM32F031K6 MCU board provides an affordable and flexible platform for experimenting with STM32 microcontrollers in 32-pin packages. Featuring Arduino™ Nano connectivity, it allows easy expansion with specialized shields, while being mbed-enabled for seamless integration with online resources. The

board includes an on-board ST-LINK/V2-1 debugger/programmer, supporting USB reenumeration with three interfaces: Virtual Com port, mass storage, and debug port. It offers a flexible power supply through either USB VBUS or an external source. Additionally, it includes three LEDs (LD1 for USB communication, LD2 for power,

and LD3 as a user LED) and a reset push button. The STM32 Nucleo-32 board is supported by various Integrated Development Environments (IDEs) such as IAR™, Keil®, and GCC-based IDEs like AC6 SW4STM32, making it a versatile tool for developers.

Nucleo 32 with STM32F031K6 MCU double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

ARM Cortex-M0

MCU Memory (KB)

32

Silicon Vendor

STMicroelectronics

Pin count

32

RAM (Bytes)

4096

You complete me!

Accessories

Click Shield for Nucleo-32 is the perfect way to expand your development board's functionalities with STM32 Nucleo-32 pinout. The Click Shield for Nucleo-32 provides two mikroBUS™ sockets to add any functionality from our ever-growing range of Click boards™. We are fully stocked with everything, from sensors and WiFi transceivers to motor control and audio amplifiers. The Click Shield for Nucleo-32 is compatible with the STM32 Nucleo-32 board, providing an affordable and flexible way for users to try out new ideas and quickly create prototypes with any STM32 microcontrollers, choosing from the various combinations of performance, power consumption, and features. The STM32 Nucleo-32 boards do not require any separate probe as they integrate the ST-LINK/V2-1 debugger/programmer and come with the STM32 comprehensive software HAL library and various packaged software examples. This development platform provides users with an effortless and common way to combine the STM32 Nucleo-32 footprint compatible board with their favorite Click boards™ in their upcoming projects.

Click Shield for Nucleo-32 accessories 1 image

Used MCU Pins

mikroBUS™ mapper

Optocoupler 4 Output
PA0
AN
Optocoupler 3 Output
PA11
RST
Optocoupler 2 Output
PA4
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
NC
NC
PWM
Optocoupler 1 Output
PA12
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

Opto 2 Click Schematic schematic

Step by step

Project assembly

Click Shield for Nucleo-144 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Nucleo 32 with STM32F031K6 MCU as your development board.

Click Shield for Nucleo-144 front image hardware assembly
Nucleo 144 with STM32L4A6ZG MCU front image hardware assembly
Stepper 22 Click front image hardware assembly
Prog-cut hardware assembly
Stepper 22 Click complete accessories setup image hardware assembly
Nucleo-32 with STM32 MCU Access 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 image step 5 hardware assembly
Necto image step 6 hardware assembly
STM32 M4 Clicker HA MCU/Select 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 Opto 2 Click driver.

Key functions:

  • opto2_check_out1 - OUT1 Check function

  • opto2_check_out2 - OUT2 Check function

  • opto2_check_out3 - OUT3 Check function

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 Opto 2 Click example
 * 
 * # Description
 * This application used to provide an optical isolation of sensitive microcontroller.
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Initializes device selects the outputs (OUT1 - OUT4) which state be checked.
 * 
 * ## Application Task  
 * Performs the check procedure for selected outputs and logs the states from that
  outputs on USB UART. Repeat the check procedure every 2 seconds.

 * 
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "opto2.h"

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

static opto2_t opto2;
static log_t logger;

static uint8_t sel_output;

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

void opto2_set_logger ( uint8_t sel_out1, uint8_t sel_out2, uint8_t sel_out3, uint8_t sel_out4 )
{
    
    if ( sel_out1 > 1 )
    { 
        sel_out1 = 1;
    }
    if ( sel_out2 > 1 )
    {
        sel_out2 = 1;
    }
    if ( sel_out3 > 1 )
    {
        sel_out3 = 1;
    }
    if ( sel_out4 > 1 )
    {
        sel_out4 = 1;
    }

    sel_output = 0;
    sel_output |= sel_out1;
    sel_output |= sel_out2 << 1;
    sel_output |= sel_out3 << 2;
    sel_output |= sel_out4 << 3;
}

void application_init ( void )
{
    log_cfg_t log_cfg;
    opto2_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 );

    opto2_cfg_setup( &cfg );
    OPTO2_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    opto2_init( &opto2, &cfg );

    log_info( &logger, "---- Application Init ----" );

    opto2_set_logger( 1, 1, 0, 0 );
    log_printf( &logger, "OPTO 2 is initialized \r\n" );
    log_printf( &logger, "" );
    Delay_ms( 200 );
}

void application_task ( void )
{
    uint8_t check_output;
    uint8_t cnt;
    uint8_t tmp;

    tmp = 1;

    for ( cnt = 0; cnt < 4; cnt++ )
    {
        switch ( sel_output & tmp )
        {
            case 0x01 :
            {
                check_output = opto2_check_out1( &opto2 );

                if ( check_output == 0 )
                {
                    log_printf( &logger, "OUT1 is low\r\n" );
                }
                else
                {
                    log_printf( &logger, "OUT1 is high\r\n" );
                }
                break;
            }
            case 0x02 :
            {
                check_output = opto2_check_out2( &opto2 );

                if ( check_output == 0 )
                {
                    log_printf( &logger, "OUT2 is low\r\n" );
                }
                else
                {
                    log_printf( &logger, "OUT2 is high\r\n" );
                }
                break;
            }
            case 0x04 :
            {
                check_output = opto2_check_out3( &opto2 );

                if ( check_output == 0 )
                {
                    log_printf( &logger, "OUT3 is low\r\n" );
                }
                else
                {
                    log_printf( &logger, "OUT3 is high\r\n" );
                }
                break;
            }
            case 0x08 :
            {
                check_output = opto2_check_out4( &opto2 );

                if ( check_output == 0 )
                {
                    log_printf( &logger, "OUT4 is low\r\n" );
                }
                else
                {
                    log_printf( &logger, "OUT4 is high\r\n" );
                }
                break;
            }
            default :
            {
                break;
            }
        }

        tmp <<= 1;
    }

    Delay_ms( 2000 );
}

void main ( void )
{
    application_init( );

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

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

Additional Support

Resources

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