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IoT ExpressLink 3 Click with UNI Clicker

Published Nov 15, 2023

Click board™

IoT ExpressLink 3 Click

Development board

UNI Clicker

Compiler

NECTO Studio

MCU

STM32F407ZG

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

UNI Clicker is a compact development board designed as a complete solution that brings the flexibility of add-on Click boards™ to your favorite microcontroller, making it a perfect starter kit for implementing your ideas. It supports a wide range of microcontrollers, such as different ARM, PIC32, dsPIC, PIC, and AVR from various vendors like Microchip, ST, NXP, and TI (regardless of their number of pins), four mikroBUS™ sockets for Click board™ connectivity, a USB connector, LED indicators, buttons, a debugger/programmer connector, and two 26-pin headers for interfacing with external electronics. Thanks to innovative manufacturing technology, it allows you to build

gadgets with unique functionalities and features quickly. Each part of the UNI Clicker development kit contains the components necessary for the most efficient operation of the same board. In addition to the possibility of choosing the UNI Clicker programming method, using a third-party programmer or CODEGRIP/mikroProg connected to onboard JTAG/SWD header, the UNI Clicker board also includes a clean and regulated power supply module for the development kit. It provides two ways of board-powering; through the USB Type-C (USB-C) connector, where onboard voltage regulators provide the appropriate voltage levels to each component on the board, or using a Li-Po/Li

Ion battery via an onboard battery connector. All communication methods that mikroBUS™ itself supports are on this board (plus USB HOST/DEVICE), including the well-established mikroBUS™ socket, a standardized socket for the MCU card (SiBRAIN standard), and several user-configurable buttons and LED indicators. UNI Clicker is an integral part of the Mikroe ecosystem, allowing you to create a new application in minutes. Natively supported by Mikroe software tools, it covers many aspects of prototyping thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.

UNI clicker double image

Microcontroller Overview

MCU Card / MCU

default

Type

8th Generation

Architecture

ARM Cortex-M4

MCU Memory (KB)

1024

Silicon Vendor

STMicroelectronics

Pin count

144

RAM (Bytes)

196608

Used MCU Pins

mikroBUS™ mapper

Reset Nora Module
PA3
AN
Device Enable / ID SEL
PE11
RST
Chip Select / ID COMM
PA4
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
Module Wake Up
PD12
PWM
Event Interrupt
PD3
INT
UART TX
PB6
TX
UART RX
PB7
RX
NC
NC
SCL
NC
NC
SDA
NC
NC
5V
Ground
GND
GND
1

Take a closer look

Schematic

IoT ExpressLink 3 Click Schematic schematic

Step by step

Project assembly

UNI Clicker front image hardware assembly

Start by selecting your development board and Click board™. Begin with the UNI Clicker as your development board.

UNI Clicker front image hardware assembly
Thermo 28 Click front image hardware assembly
SiBRAIN for STM32F745VG front image hardware assembly
Prog-cut hardware assembly
UNI Clicker MB 1 - upright/with-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
Necto image step 7 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

After loading the code example, pressing the "DEBUG" button builds and programs it on the selected setup.

Application Output Step 1

After programming is completed, a header with buttons for various actions available in the IDE appears. By clicking the green "PLAY "button, we start reading the results achieved with Click board™.

Application Output Step 3

Upon completion of programming, the Application Output tab is automatically opened, where the achieved result can be read. In case of an inability to perform the Debug function, check if a proper connection between the MCU used by the setup and the CODEGRIP programmer has been established. A detailed explanation of the CODEGRIP-board connection can be found in the CODEGRIP User Manual. Please find it in the RESOURCES section.

Application Output Step 4

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

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 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 ( 2000 );

    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 ( 2000 );
    
    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( );
    }
}

void main ( void ) 
{
    application_init( );

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

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