30 min

Communicate easily with more than one device with MAX7317 and STM32F429ZI

Expand your horizons: Multi-port I/O magic unleashed!

Expand 8 Click with Fusion for STM32 v8

Published Oct 07, 2023

Click board™

Expand 8 Click

Development board

Fusion for STM32 v8


NECTO Studio



Enhance the connectivity and versatility of your electronic projects with our multi-port I/O expander, featuring bi-directional input/outputs for seamless data flow and control expansion



Hardware Overview

How does it work?

Expand 8 Click is based on the MAX7317, a general-purpose input/output (GPIO) peripheral from Analog Devices that provides 10 I/O ports, P0 to P9, controlled through a high-speed SPI-compatible serial interface. Each port, P0 to P9, can be configured as open-drain, current-sink outputs rated at 20mA maximum, CMOS inputs, or open-drain outputs. Loads should be connected to a supply voltage no higher than 7V. The MAX7317 contains ten 8-bit internal registers. These ten registers addressed as 0x00 - 0x09 control an I/O

port each. Write 0x00 to the output register to set the port as a logic-low output or 0x01 to set the port as a logic-high output or logic input. Expand 8 Click communicates with MCU through a 16-bit 4-wire serial interface compatible with standard SPI, QSPI™, and MICROWIRE™ guaranteed to operate at 35Mbps on its 3.3V power supply. During the Power-Up sequence, all control registers of the MAX7317 are in a reset state. Power-Up status sets I/O ports, P0 to P9, into a high impedance state and puts the device into

Shutdown mode. The I/O ports P0–P9 remain high impedance with up to 8V asserted on them when the MAX7317 is powered down. Therefore, it can be used in hot-swap applications. This Click board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. Also, it comes equipped with a library containing functions and an example code that can be used as a reference for further development.

Expand 8 Click top side image
Expand 8 Click bottom side image

Features overview

Development board

Fusion for STM32 v8 is a development board specially designed for the needs of rapid development of embedded applications. It supports a wide range of microcontrollers, such as different 32-bit ARM® Cortex®-M based MCUs from STMicroelectronics, regardless of their number of pins, and a broad set of unique functions, such as the first-ever embedded debugger/programmer over WiFi. The development board is well organized and designed so that the end-user has all the necessary elements, such as switches, buttons, indicators, connectors, and others, in one place. Thanks to innovative manufacturing technology, Fusion for STM32 v8 provides a fluid and immersive working experience, allowing

access anywhere and under any circumstances at any time. Each part of the Fusion for STM32 v8 development board contains the components necessary for the most efficient operation of the same board. An advanced integrated CODEGRIP programmer/debugger module offers many valuable programming/debugging options, including support for JTAG, SWD, and SWO Trace (Single Wire Output)), and seamless integration with the Mikroe software environment. Besides, it also includes a clean and regulated power supply module for the development board. It can use a wide range of external power sources, including a battery, an external 12V power supply, and a power source via the USB Type-C (USB-C) connector.

Communication options such as USB-UART, USB HOST/DEVICE, CAN (on the MCU card, if supported), and Ethernet is also included. In addition, it also has the well-established mikroBUS™ standard, a standardized socket for the MCU card (SiBRAIN standard), and two display options for the TFT board line of products and character-based LCD. Fusion for STM32 v8 is an integral part of the Mikroe ecosystem for rapid development. Natively supported by Mikroe software tools, it covers many aspects of prototyping and development thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.

Fusion for STM32 v8 horizontal image

Microcontroller Overview

MCU Card / MCU



8th Generation


ARM Cortex-M4

MCU Memory (KB)


Silicon Vendor


Pin count


RAM (Bytes)


Used MCU Pins

mikroBUS™ mapper

SPI Chip Select
SPI Clock
Power Supply

Take a closer look


Expand 8 Click Schematic schematic

Step by step

Project assembly

Fusion for PIC v8 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Fusion for STM32 v8 as your development board.

Fusion for PIC v8 front image hardware assembly
GNSS2 Click front image hardware assembly
SiBRAIN for PIC32MZ1024EFK144 front image hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
v8 SiBRAIN 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 Compiler Selection Step Image hardware assembly
NECTO Output Selection Step Image hardware assembly
Necto image step 6 hardware assembly
Necto image step 7 hardware assembly
Necto image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Necto PreFlash Image hardware assembly

Track your results in real time

Application Output

After pressing the "FLASH" button on the left-side panel, it is necessary to open the UART terminal to display the achieved results. By clicking on the Tools icon in the right-hand panel, multiple different functions are displayed, among which is the UART Terminal. Click on the offered "UART Terminal" icon.

UART Application Output Step 1

Once the UART terminal is opened, the window takes on a new form. At the top of the tab are two buttons, one for adjusting the parameters of the UART terminal and the other for connecting the UART terminal. The tab's lower part is reserved for displaying the achieved results. Before connecting, the terminal has a Disconnected status, indicating that the terminal is not yet active. Before connecting, it is necessary to check the set parameters of the UART terminal. Click on the "OPTIONS" button.

UART Application Output Step 2

In the newly opened UART Terminal Options field, we check if the terminal settings are correct, such as the set port and the Baud rate of UART communication. If the data is not displayed properly, it is possible that the Baud rate value is not set correctly and needs to be adjusted to 115200. If all the parameters are set correctly, click on "CONFIGURE".

UART Application Output Step 3

The next step is to click on the "CONNECT" button, after which the terminal status changes from Disconnected to Connected in green, and the data is displayed in the Received data field.

UART Application Output Step 4

Software Support

Library Description

This library contains API for Expand 8 Click driver.

Key functions:

  • expand8_write_data - Generic write data function

  • expand8_read_data - Generic read data function

  • expand8_set_port - Set port 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 Expand8 Click example
 * # Description
 * This is an example that demonstrates the use of the Expand 8 click board.
 * The demo application is composed of two sections :
 * ## Application Init
 * Initialization driver enables - SPI, also write log.
 * ## Application Task
 * This example is working by toggling each of 10 available ports every 1 second.
 * Results are being sent to the Uart Terminal where you can track their changes.
 * @author Mikroe Team

#include "board.h"
#include "log.h"
#include "expand8.h"

static expand8_t expand8;
static log_t logger;
uint8_t select_port;

void application_init ( void )
    log_cfg_t log_cfg;  /**< Logger config object. */
    expand8_cfg_t expand8_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.

    expand8_cfg_setup( &expand8_cfg );
    EXPAND8_MAP_MIKROBUS( expand8_cfg, MIKROBUS_1 );
    err_t init_flag  = expand8_init( &expand8, &expand8_cfg );
    if ( SPI_MASTER_ERROR == init_flag ) {
        log_error( &logger, " Application Init Error. " );
        log_info( &logger, " Please, run program again... " );

        for ( ; ; );

    log_info( &logger, " Application Task " );
    select_port = EXPAND8_ADDR_OUT_LVL_PORT_P0;
    Delay_ms( 100 );

void application_task ( void )
    expand8_set_port( &expand8, select_port, EXPAND8_SET_LOW_IMPEDANCE );
    log_printf( &logger, "     Port P%d - ON\r\n", ( uint16_t ) select_port );
    log_printf( &logger, "- - - - - - - - - - -\r\n" );
    Delay_ms( 1000 );
    expand8_set_port( &expand8, select_port, EXPAND8_SET_HIGH_IMPEDANCE );
    log_printf( &logger, "     Port P%d - OFF\r\n", ( uint16_t ) select_port );
    log_printf( &logger, "---------------------\r\n" );
    Delay_ms( 1000 );

    if ( select_port > EXPAND8_ADDR_OUT_LVL_PORT_P9 ) 
        select_port = EXPAND8_ADDR_OUT_LVL_PORT_P0;

void main ( void )
    application_init( );

    for ( ; ; ) 
        application_task( );

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

Additional Support