Beginner
10 min

Achieve general-purpose I/O expansion with MCP23S17 and STM32F031K6

Plug, Play, Expand: Redefining connectivity with port expanders!

EXPAND Click with Nucleo 32 with STM32F031K6 MCU

Published Oct 01, 2024

Click board™

EXPAND Click

Dev. board

Nucleo 32 with STM32F031K6 MCU

Compiler

NECTO Studio

MCU

STM32F031K6

Expand your project's input and output capabilities without complex wiring or hardware modifications

A

A

Hardware Overview

How does it work?

Expand Click is based on the MCP23S17, a 16-bit general-purpose parallel I/O expansion with the serial interface from Microchip. The MCP23S17 consists of multiple 8-bit configuration registers for input, output, and polarity selection. The host MCU can enable the I/Os as either inputs or outputs by writing the I/O configuration bits with data for each input or output kept in the corresponding input or output register. This port expander represents a simple solution when additional I/Os are needed while keeping interconnections to a minimum. It features two double-row unpopulated headers for connecting I/O devices. This Click board™ communicates with MCU using the standard 4-Wire

SPI serial interface with a maximum 10MHz frequency. The MCP23S17 has a 7-bit slave address with the first four MSBs fixed to 0100. The address pins A0, A1, and A2 are programmed by the user and determine the value of the last three LSBs of the slave address, which can be selected by positioning onboard SMD jumpers labeled as HARDWARE ADDRESS SEL to an appropriate position marked as 1 or 0. This way, the MCP23S17 provides the opportunity to use more Extend Clicks on a single host MCU. Besides, it also has an interrupt feature, routed to the INT pin of the mikroBUS™ socket, indicating to the host controller that an input state has been changed

alongside the general reset feature. Two interrupt pins on the MCP23S17 can be associated with their respective ports or logically OR’ed together so that both pins will activate if either port causes an interrupt. The desired interrupt port can be selected by positioning an onboard SMD jumper labeled J4 in an appropriate position. 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 for further development.

EXPAND Click hardware overview 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

NC
NC
AN
Reset
PA11
RST
SPI Chip Select
PA4
CS
SPI Clock
PB3
SCK
SPI Data OUT
PB4
MISO
SPI Data IN
PB5
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
NC
NC
PWM
Interrupt
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

EXPAND 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
Board mapper by product8 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

Software Support

Library Description

This library contains API for EXPAND Click driver.

Key functions:

  • expand_set_direction_port_a - Set expander PORTA direction function

  • expand_write_port_a - Write one byte of data to register for PORTA function

  • expand_reset - Reset 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 Expand Click example
 * 
 * # Description
 * This applicatioin use for expansion I/O lines.
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Initialization driver enable's - GPIO,
 * reset MCP23S17 chip, set PORTA to be output and PORTB to be input,
 * set default configuration and start write log.
 * 
 * ## Application Task  
 * This is a example which demonstrates the use of Expand Click board.
 * Expand Click communicates with register via SPI protocol by write and read from register,
 * set configuration and state and read configuration and state.
 * Results are being sent to the Usart Terminal where you can track their changes.
 * All data logs on usb uart for aproximetly every 500 ms.
 * 
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "expand.h"

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

static expand_t expand;
static log_t logger;

static uint8_t port_status;
static uint8_t position;
static uint16_t pin_position;

void application_init ( void )
{
    log_cfg_t log_cfg;
    expand_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.

    expand_cfg_setup( &cfg );
    EXPAND_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    expand_init( &expand, &cfg );
    
    expand_default_configuration( &expand, EXPAND_SPI_MODULE_POSITION_0 );

    expand_set_direction_port_a( &expand, EXPAND_SPI_MODULE_POSITION_0, EXPAND_PORT_DIRECTION_OUTPUT );
    
    expand_set_direction_port_b( &expand, EXPAND_SPI_MODULE_POSITION_0, EXPAND_PORT_DIRECTION_INPUT );
    
    expand_set_pull_ups_port_b( &expand, EXPAND_SPI_MODULE_POSITION_0, 0xFF );
}

void application_task ( void )
{
    pin_position = 1;

    for ( position = 0; position < 8; position++ )
    {
        expand_write_port_a( &expand, EXPAND_SPI_MODULE_POSITION_0, pin_position );
        log_printf( &logger, " PA%d set\r\n", (uint16_t) position );

        port_status = expand_read_port_b( &expand, EXPAND_SPI_MODULE_POSITION_0 );

        log_printf( &logger, " Status PB (input) : %d  \r\n", (uint16_t) port_status );
        log_printf( &logger, "----------------\r\n" );
        
        pin_position <<= 1;

        Delay_ms ( 500 );
    }
}

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;
}


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

Additional Support

Resources

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