Beginner
10 min

Collect, store, and analyze data effortlessly across various applications with NORA-W256WS and STM32F091RC

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IoT ExpressLink 3 Click with Nucleo-64 with STM32F091RC MCU

Published Feb 26, 2024

Click board™

IoT ExpressLink 3 Click

Dev. board

Nucleo-64 with STM32F091RC MCU

Compiler

NECTO Studio

MCU

STM32F091RC

With IoT ExpressLink, you can unlock the potential of your projects and seamlessly connect to the Cloud. No need for specialized knowledge – we've got security covered!

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Hardware Overview

How does it work?

IoT ExpressLink 3 Click is based on the NORA-W256WS, a standalone multi-radio module from u-blox. Under the hood is the ESP32-S3, a radio for wireless communication, and a dual-core MCU from Esspressif. This powerful 32-bit microcontroller has 512KB of RAM and 8192KB of flash memory. It features host software OTA, module firmware OTA, secure boot, end-to-end security (TLS), MQTT, stateless AT commands, WPA/WPA2/WPA3, and more. With pre-flashed AWS IoT ExpressLink software that offers out-of-the-box connectivity with Amazon Web Services (AWS), you can benefit from convenient cloud

access to applications and all other services that AWS provides. The NORA-W256WS module comes with a printed antenna that serves both radios. You can only use one at a time. The module also features an RGB LED that visualizes the system statuses. IoT ExpressLink 3 Click uses a standard 2-Wire UART interface to communicate with the host MCU, with commonly used UART RX and TX pins over the 115200bps baud rate. The ExpressLink events can be monitored over the EVT pin. The module enters a standby state and stops the Wi-Fi until the wake WK pin is asserted. Toggling this pin when the module is in deep sleep mode allows

the module to enter active wake mode. The module can be reset (rebooted) over the RST pin. You can also reset the module over the RESET button. In addition, you can reset the ExpressLink over the RSN pin. 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.

IoT ExpressLink 3 Click hardware overview image

Features overview

Development board

Nucleo-64 with STM32F091RC 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 STM32F091RC MCU double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

ARM Cortex-M0

MCU Memory (KB)

256

Silicon Vendor

STMicroelectronics

Pin count

64

RAM (Bytes)

32768

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

Reset Nora Module
PC0
AN
Device Enable / ID SEL
PC12
RST
Chip Select / ID COMM
PB12
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
Module Wake Up
PC8
PWM
Event Interrupt
PC14
INT
UART TX
PA2
TX
UART RX
PA3
RX
NC
NC
SCL
NC
NC
SDA
NC
NC
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

IoT ExpressLink 3 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 STM32F091RC 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
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
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

Software Support

Library Description

This library contains API for IoT ExpressLink 3 Click driver.

Key functions:

  • iotexpresslink3_reset_device - This function resets device by toggling the RST pin state.

  • iotexpresslink3_send_cmd - This function send command string by using UART serial interface.

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 main.c
 * @brief IoT ExpressLink 3 Click Example.
 *
 * # Description
 * This example demonstrates the use of IoT ExpressLink 3 Click board by bridging the USB UART
 * to mikroBUS UART which allows the Click board to establish a connection with
 * the IoT ExpressLink over the Quick Connect demo application without an AWS account.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes the driver, resets the Click board to factory default settings, reads
 * and displays the vendor model and thing name on the USB UART, sets the WiFi credentials,
 * and attempts to connect to the AWS Cloud. If the initial attempt fails and the error
 * message "Failed to access network" or "Failed to login AWS (MQTT) broker" appears,
 * check the WiFi credentials and try running the example again.
 *
 * ## Application Task
 * All data received from the USB UART will be forwarded to mikroBUS UART, and vice versa.
 * At this point you should disconnect from the UART terminal and run the Quick Connect
 * demo application.
 *
 * ## Additional Function
 * - static void iotexpresslink3_clear_app_buf ( void )
 * - static err_t iotexpresslink3_process ( iotexpresslink3_t *ctx )
 * - static err_t iotexpresslink3_read_response ( iotexpresslink3_t *ctx )
 *
 * @note
 * To run the demo, follow the below steps:
 * 1. If you opened a terminal application in the previous step, be sure to disconnect that
 *    application from the serial port. 
 * 2. Download the Quick Connect executable: 
 *    Mac: https://quickconnectexpresslinkutility.s3.us-west-2.amazonaws.com/QuickConnect_v1.9_macos.x64.tar.gz
 *    Windows: https://quickconnectexpresslinkutility.s3.us-west-2.amazonaws.com/QuickConnect_v1.9_windows.x64.zip
 *    Linux: https://quickconnectexpresslinkutility.s3.us-west-2.amazonaws.com/QuickConnect_v1.9_linux.x64.tar.gz
 * 3. Unzip the package, and follow the steps from the README file.
 * 
 * The demo will connect to IoT ExpressLink and give you an URL that you can use to visualize data
 * flowing from the device to the cloud using AT+SEND commands. The demo will run for up
 * to two minutes, and afterwards, you will be able to type AT+SEND commands yourself and
 * see the data coming in on the visualizer.
 *
 * @author Stefan Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "iotexpresslink3.h"

// Enter valid WiFi credentials below
#define WIFI_SSID               "MikroE Public"     // WiFi SSID
#define WIFI_PASS               "mikroe.guest"      // WiFi Password

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

static iotexpresslink3_t iotexpresslink3;
static log_t logger;

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

/**
 * @brief IoT ExpressLink 3 clearing application buffer.
 * @details This function clears memory of application buffer and reset its length.
 * @note None.
 */
static void iotexpresslink3_clear_app_buf ( void );

/**
 * @brief IoT ExpressLink 3 data reading function.
 * @details This function reads data from device and concatenates data to application buffer. 
 * @param[in] ctx : Click context object.
 * See #iotexpresslink3_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 iotexpresslink3_process ( iotexpresslink3_t *ctx );

/**
 * @brief IoT ExpressLink read response function.
 * @details This function waits for a response message, reads and displays it on the USB UART.
 * @param[in] ctx : Click context object.
 * See #iotexpresslink_t object definition for detailed explanation.
 * @return @li @c  0 - OK response.
 *         @li @c -2 - Timeout error.
 *         @li @c -3 - Command error.
 *         @li @c -4 - Unknown error.
 * See #err_t definition for detailed explanation.
 * @note None.
 */
static err_t iotexpresslink3_read_response ( iotexpresslink3_t *ctx );

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    iotexpresslink3_cfg_t iotexpresslink3_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.
    iotexpresslink3_cfg_setup( &iotexpresslink3_cfg );
    IOTEXPRESSLINK3_MAP_MIKROBUS( iotexpresslink3_cfg, MIKROBUS_1 );
    if ( UART_ERROR == iotexpresslink3_init( &iotexpresslink3, &iotexpresslink3_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    
    log_printf( &logger, "Reset device\r\n\n" );
    iotexpresslink3_reset_device ( &iotexpresslink3 );
    Delay_ms ( 1000 );
    Delay_ms ( 1000 );

    log_printf( &logger, "Factory reset\r\n" );
    strcpy ( app_buf, IOTEXPRESSLINK3_CMD_FACTORY_RESET );
    iotexpresslink3_send_cmd ( &iotexpresslink3, app_buf );
    iotexpresslink3_read_response ( &iotexpresslink3 );
    Delay_ms ( 1000 );
    Delay_ms ( 1000 );
    
    log_printf( &logger, "Vendor model\r\n" );
    strcpy ( app_buf, IOTEXPRESSLINK3_CMD_CONF_CHECK );
    strcat ( app_buf, IOTEXPRESSLINK3_CMD_SEPARATOR );
    strcat ( app_buf, IOTEXPRESSLINK3_CONF_KEY_ABOUT );
    iotexpresslink3_send_cmd ( &iotexpresslink3, app_buf );
    iotexpresslink3_read_response ( &iotexpresslink3 );
    
    log_printf( &logger, "Thing name\r\n" );
    strcpy ( app_buf, IOTEXPRESSLINK3_CMD_CONF_CHECK );
    strcat ( app_buf, IOTEXPRESSLINK3_CMD_SEPARATOR );
    strcat ( app_buf, IOTEXPRESSLINK3_CONF_KEY_THING_NAME );
    iotexpresslink3_send_cmd ( &iotexpresslink3, app_buf );
    iotexpresslink3_read_response ( &iotexpresslink3 );
    
    log_printf( &logger, "WiFi SSID\r\n" );
    strcpy ( app_buf, IOTEXPRESSLINK3_CMD_CONF );
    strcat ( app_buf, IOTEXPRESSLINK3_CMD_SEPARATOR );
    strcat ( app_buf, IOTEXPRESSLINK3_CONF_KEY_SSID );
    strcat ( app_buf, IOTEXPRESSLINK3_CMD_SIGN_EQUAL );
    strcat ( app_buf, WIFI_SSID );
    iotexpresslink3_send_cmd ( &iotexpresslink3, app_buf );
    iotexpresslink3_read_response ( &iotexpresslink3 );
    
    log_printf( &logger, "WiFi Password\r\n" );
    strcpy ( app_buf, IOTEXPRESSLINK3_CMD_CONF );
    strcat ( app_buf, IOTEXPRESSLINK3_CMD_SEPARATOR );
    strcat ( app_buf, IOTEXPRESSLINK3_CONF_KEY_PASSPHRASE );
    strcat ( app_buf, IOTEXPRESSLINK3_CMD_SIGN_EQUAL );
    strcat ( app_buf, WIFI_PASS );
    iotexpresslink3_send_cmd ( &iotexpresslink3, app_buf );
    iotexpresslink3_read_response ( &iotexpresslink3 );
    
    log_printf( &logger, "Try to connect\r\n" );
    strcpy ( app_buf, IOTEXPRESSLINK3_CMD_CONNECT );
    iotexpresslink3_send_cmd ( &iotexpresslink3, app_buf );
    iotexpresslink3_read_response ( &iotexpresslink3 );
    
    log_info( &logger, " Application Task " );
    
    log_printf( &logger, "Now close the UART terminal and switch to the QuickConnect app\r\n" );
    Delay_ms ( 1000 );
    
    uart_set_blocking( &logger.uart, false );
}

void application_task ( void ) 
{
    app_buf_len = uart_read( &logger.uart, app_buf, PROCESS_BUFFER_SIZE );
    if ( app_buf_len > 0 ) 
    {
        uart_write ( &iotexpresslink3.uart, app_buf, app_buf_len );
        iotexpresslink3_clear_app_buf( );
    }
    app_buf_len = uart_read( &iotexpresslink3.uart, app_buf, PROCESS_BUFFER_SIZE );
    if ( app_buf_len > 0 ) 
    {
        uart_write ( &logger.uart, app_buf, app_buf_len );
        iotexpresslink3_clear_app_buf( );
    }
}

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;
}

static void iotexpresslink3_clear_app_buf ( void ) 
{
    memset( app_buf, 0, APP_BUFFER_SIZE );
    app_buf_len = 0;
}

static void iotexpresslink3_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 iotexpresslink3_process ( iotexpresslink3_t *ctx ) 
{
    uint8_t rx_buf[ PROCESS_BUFFER_SIZE ] = { 0 };
    int32_t overflow_bytes = 0;
    int32_t rx_cnt = 0;
    int32_t rx_size = iotexpresslink3_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 IOTEXPRESSLINK3_OK;
    }
    return IOTEXPRESSLINK3_ERROR;
}


static err_t iotexpresslink3_read_response ( iotexpresslink3_t *ctx ) 
{
    uint32_t timeout_cnt = 0;
    uint32_t timeout = 30000;
    iotexpresslink3_clear_app_buf ( );
    iotexpresslink3_process( ctx );
    while ( ( 0 == strstr( app_buf, IOTEXPRESSLINK3_RSP_OK ) ) &&
            ( 0 == strstr( app_buf, IOTEXPRESSLINK3_RSP_ERR ) ) )
    {
        iotexpresslink3_process( ctx );
        if ( timeout_cnt++ > timeout )
        {
            iotexpresslink3_clear_app_buf( );
            return IOTEXPRESSLINK3_ERROR_TIMEOUT;
        }
        Delay_ms ( 1 );
    }
    Delay_ms ( 100 );
    iotexpresslink3_process( ctx );
    if ( app_buf_len > 0 ) 
    {
        log_printf( &logger, "%s\r\n", app_buf );
    }
    if ( strstr( app_buf, IOTEXPRESSLINK3_RSP_OK ) )
    {
        iotexpresslink3_clear_app_buf( );
        return IOTEXPRESSLINK3_OK;
    }
    else if ( strstr( app_buf, IOTEXPRESSLINK3_RSP_ERR ) )
    {
        iotexpresslink3_clear_app_buf( );
        return IOTEXPRESSLINK3_ERROR_CMD;
    }
    iotexpresslink3_clear_app_buf( );
    return IOTEXPRESSLINK3_ERROR_UNKNOWN;
}

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

Additional Support

Resources

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