Integrate fiber-optic communication using IF-D91, IF-E97 and STM32L496AG for lightning-speed data exchange

Transforming designs with fiber-optic innovation

Fiber Opt click with Discovery kit with STM32L496AG MCU

Published Jul 22, 2025

Click board™

Fiber Opt click

Dev. board

Discovery kit with STM32L496AG MCU

Compiler

NECTO Studio

MCU

STM32L496AG

Integrate high-speed fiber-optic communication and establish reliable, secure networks to meet growing demands for rapid data exchange while enhancing overall performance and efficiency.

Hardware Overview

How does it work?

Fiber Opt Click is based on one IF-D91, a fiber-optic photodiode, and one IF-E97, a fiber-optic LED, both from Industrial Fiber Optics. The IF-D91 is a high-speed photodiode detector housed in a connector-less plastic fiber optic package. Its optical response extends from 400 to 1100nm, making it compatible with a wide range of visible and near-infrared LED and laser diode sources. The detector package features an internal micro-lens and a precision-molded PBT housing to ensure efficient optical coupling with standard 1000μm core 2.2mm jacketed plastic fiber cable capable of 100Mbps data rates. The IF-D91 can also be used for analog video links with bandwidths

up to 70MHz. The other precision-molded PBT housing with internal micro-lens, the IF-E97, is a high-optical-output visible red LED. The housing ensures efficient optical coupling with the same standard jacketed plastic fiber cable. The output spectrum is produced by a GaAlAs die, which peaks at 650nm, representing an optimal transmission window for PMMA plastic optical fiber. The visible red light has low attenuation in PMMA plastic fiber, aids troubleshooting installations, and is the main reason the IF-E97 achieves data rates of 1Mbps. This Click board™ communicates with the host MCU over selectable pins of the mikroBUS™ socket. Transmission can

be selected through the TX SEL selection jumper between the UART TX pin or PWM pin of the mikroBUS™ socket, as UART is selected by default. Received data is available on the RX pin of the mikroBUS™ socket. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the PWR 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.

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

SCK

MISO

MOSI

Power Supply

3.3V

Ground

GND

GPIO TX

PA0

PWM

INT

UART TX

PG10

UART RX

PB6

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 Fiber Opt Click driver.

Key functions:

fiberopt_generic_write - Generic single write function
fiberopt_generic_read - Generic single read 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 Fiber Opt Click example
 * 
 * # Description
 * This example demonstrates the use of an Fiber Opt Click board by showing
 * the communication between the two Click boards.
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Initalizes device and makes an initial log.
 * 
 * ## Application Task
 * Depending on the selected application mode, it reads all the received data or 
 * sends the desired text message with the message counter once per second.
 * 
 * \author MikroE Team
 *
 */

#include "board.h"
#include "log.h"
#include "fiberopt.h"

// Comment out the line below in order to switch the application mode to receiver
#define DEMO_APP_TRANSMITTER

// Text message to send in the transmitter application mode
#define DEMO_TEXT_MESSAGE           "MIKROE - Fiber Opt Click board\r\n\0"

static fiberopt_t fiberopt;
static log_t logger;

void application_init ( void )
{
    log_cfg_t log_cfg;
    fiberopt_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.
    fiberopt_cfg_setup( &cfg );
    FIBEROPT_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    fiberopt_init( &fiberopt, &cfg );

#ifdef DEMO_APP_TRANSMITTER
    log_printf( &logger, " Application Mode: Transmitter\r\n" );
#else
    log_printf( &logger, " Application Mode: Receiver\r\n" );
#endif
    log_info( &logger, " Application Task " );
    Delay_ms ( 100 );
}

void application_task ( void )
{
#ifdef DEMO_APP_TRANSMITTER
    fiberopt_generic_write( &fiberopt, DEMO_TEXT_MESSAGE, strlen( DEMO_TEXT_MESSAGE ) );
    log_printf( &logger, "%s", ( char * ) DEMO_TEXT_MESSAGE );
    Delay_ms ( 1000 ); 
#else
    uint8_t rx_byte = 0;
    if ( 1 == fiberopt_generic_read( &fiberopt, &rx_byte, 1 ) )
    {
       log_printf( &logger, "%c", rx_byte );
    }
#endif
}

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;
}


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