Intermediate
30 min

Tailor-made Bluetooth solution with WT41u and MK22FN512VLH12

Wireless wonders at your fingertips

Bluetooth 2 Click with Kinetis Clicker

Published Jun 19, 2023

Click board™

Bluetooth 2 Click

Dev Board

Kinetis Clicker

Compiler

NECTO Studio

MCU

MK22FN512VLH12

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Hardware Overview

How does it work?

Bluetooth 2 Click is based on the WT41u, a fully integrated Bluetooth 2.1 + EDR, Class 1 module from Silicon Labs. Combining an onboard chip antenna, Bluetooth radio, and an onboard iWRAP Bluetooth Stack, the WT41u provides a superior link budget and 650-meter line-of-sight connectivity for Bluetooth applications with extreme radio performance or required reliability. Thanks to Bluegiga's iWRAP Bluetooth stack, the WT41u implements 13 different Bluetooth profiles and Apple iAP connectivity ensuring quick time-to-market. This Click board™ represents an ideal solution for rapidly integrating high-performing Bluetooth wireless technology without investing

several months in Bluetooth radio and stack development. The WT41u communicates with MCU using the UART interface, RS232 protocol, with commonly used UART RX, TX, and hardware flow control pins UART CTS and RTS. The UART configuration parameters, such as data rate and packet format, are set using WT41u software. In addition to the UART interface, an SPI interface is available, but only for system debugging. The WT41u uses 16-bit data and a 16-bit address serial peripheral interface to program the Flash memory and set the PSKEY configurations. The CS pin has a dual function, as the CS pin of the SPI interface or CTS for UART, can be

selected by moving the SMD jumper designated as COM SEL to an appropriate position. Besides the commonly used interface pins, Bluetooth 2 Click also has a general reset and bidirectional digital/analog I/O pins routed to the RST, PWM, and AN pins of the mikroBUS™ socket, respectively. 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. However, the Click board™ comes equipped with a library containing functions and an example code that can be used, as a reference, for further development.

Bluetooth 2 Click top side image
Bluetooth 2 Click lateral side image
Bluetooth 2 Click bottom side image

Features overview

Development board

Kinetis Clicker is a compact starter development board that brings the flexibility of add-on Click boards™ to your favorite microcontroller, making it a perfect starter kit for implementing your ideas. It comes with an onboard 32-bit ARM Cortex-M4 microcontroller, the MK22FN512VLH12 from NXP Semiconductor, a USB connector, LED indicators, buttons, a mikroProg connector, and a header for interfacing with external electronics. Thanks to its compact design with clear and easy-recognizable silkscreen markings, it provides a fluid and immersive working experience, allowing access

anywhere and under any circumstances. Each part of the Kinetis Clicker development kit contains the components necessary for the most efficient operation of the same board. In addition to the possibility of choosing the Kinetis Clicker programming method, using USB HID mikroBootloader, or through an external mikroProg connector for Kinetis programmer, the Clicker board also includes a clean and regulated power supply module for the development kit. The USB-MiniAB connection provides up to 500mA of current, which is more than enough to operate all

onboard and additional modules. All communication methods that mikroBUS™ itself supports are on this board, including the well-established mikroBUS™ socket, reset button, and several buttons and LED indicators. Kinetis 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.

Kinetis Clicker double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

ARM Cortex-M4

MCU Memory (KB)

512

Silicon Vendor

NXP

Pin count

64

RAM (Bytes)

131072

Used MCU Pins

mikroBUS™ mapper

Analog Signal
PTB2
AN
Reset
PTB3
RST
Chip Select
PTC4
CS
SPI Clock
PTC5
SCK
SPI Data OUT
PTC7
MISO
SPI Data IN
PTC6
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
General Purpose I/O
PTC1
PWM
UART RTS
PTD0
INT
UART TX
PTB17
TX
UART RX
PTB16
RX
NC
NC
SCL
NC
NC
SDA
NC
NC
5V
Ground
GND
GND
1

Take a closer look

Schematic

Bluetooth 2 Click Schematic schematic

Step by step

Project assembly

Kinetis Clicker front image hardware assembly

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

Kinetis Clicker front image hardware assembly
Thermo 28 Click front image hardware assembly
Prog-cut hardware assembly
Kinetis Mini B Connector clicker - upright/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
Kinetis 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

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 Bluetooth 2 Click driver.

Key functions:

  • bluetooth2_factory_reset - This function factory resets the device

  • bluetooth2_set_device_name - This function sets the local device name

  • bluetooth2_generic_write - This function writes a desired number of data bytes 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 Bluetooth 2 Click Example.
 *
 * # Description
 * This example reads and processes data from Bluetooth 2 clicks.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes the driver, then performs a factory reset, removes all pairings, and
 * sets the local device name.
 *
 * ## Application Task
 * Logs all the received messages/responses on the USB UART, and if there's any device
 * connected to the click board the module sends a desired message every 5 seconds back to it.
 *
 * ## Additional Function
 * - static void bluetooth2_clear_app_buf ( void )
 * - static err_t bluetooth2_process ( void )
 * - static err_t bluetooth2_display_rsp ( uint16_t timeout )
 *
 * @note
 * We have used the Serial Bluetooth Terminal smartphone application for the test. 
 * A smartphone and the click board must be paired in order to exchange messages with each other.
 * 
 * @author Stefan Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "bluetooth2.h"

#define PROCESS_BUFFER_SIZE 200

#define RSP_OK              "OK."
#define RSP_READY           "READY."
#define RSP_RING            "RING"
#define RSP_NO_CARRIER      "NO CARRIER"

// Local device name.
#define DEVICE_NAME         "Bluetooth 2 Click"

// Message which will be sent to the connected device.
#define TEXT_TO_SEND        "MikroE - Bluetooth 2 click\r\n" 

// Text sending frequency in miliseconds.
#define SENDING_FREQ        5000  

static bluetooth2_t bluetooth2;
static log_t logger;

static char app_buf[ PROCESS_BUFFER_SIZE ] = { 0 };
static int32_t app_buf_len = 0;
static int32_t app_buf_cnt = 0;
static uint8_t connection_flag = 0;
static uint16_t send_cnt = 0;

/**
 * @brief Bluetooth 2 clearing application buffer.
 * @details This function clears memory of application buffer and reset its length and counter.
 * @note None.
 */
static void bluetooth2_clear_app_buf ( void );

/**
 * @brief Bluetooth 2 data reading function.
 * @details This function reads data from device and concatenates data to application buffer.
 *
 * @return @li @c  0 - Read some data.
 *         @li @c -1 - Nothing is read.
 *         @li @c -2 - Application buffer overflow.
 *
 * See #err_t definition for detailed explanation.
 * @note None.
 */
static err_t bluetooth2_process ( void );

/**
 * @brief Bluetooth 2 display response function.
 * @details This function reads data from device until it sends OK or READY message or until
 * it exceeds the timeout value.
 * @param[in] timeout : Timeout value in miliseconds.
 *
 * @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 bluetooth2_display_rsp ( uint16_t timeout );

void application_init ( void ) 
{
    log_cfg_t log_cfg;                /**< Logger config object. */
    bluetooth2_cfg_t bluetooth2_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 );
    Delay_ms( 100 );
    log_info( &logger, " Application Init " );

    // Click initialization.

    bluetooth2_cfg_setup( &bluetooth2_cfg );
    BLUETOOTH2_MAP_MIKROBUS( bluetooth2_cfg, MIKROBUS_1 );
    err_t init_flag  = bluetooth2_init( &bluetooth2, &bluetooth2_cfg );
    if ( UART_ERROR == init_flag ) 
    {
        log_error( &logger, " Application Init Error. " );
        log_info( &logger, " Please, run program again... " );

        for ( ; ; );
    }

    bluetooth2_default_cfg ( &bluetooth2 );
    bluetooth2_process( );
    bluetooth2_clear_app_buf( );
    
    log_printf( &logger, " - Factory Reset -\r\n" );
    bluetooth2_factory_reset ( &bluetooth2 );
    bluetooth2_display_rsp ( 2000 ); 
    
    log_printf( &logger, " - Enable OK response -\r\n" );
    bluetooth2_enable_ok_response ( &bluetooth2 );
    bluetooth2_display_rsp ( 1000 ); 
    
    log_printf( &logger, " - Remove Pairings -\r\n" );
    bluetooth2_remove_pairings ( &bluetooth2 );
    bluetooth2_display_rsp ( 1000 ); 
    
    log_printf( &logger, " - Set Device Name -\r\n" );
    bluetooth2_set_device_name ( &bluetooth2, DEVICE_NAME );
    bluetooth2_display_rsp ( 1000 ); 
    
    log_info( &logger, " Application Task " );
}

void application_task ( void ) 
{
    bluetooth2_process();
    if ( app_buf_len > 0 ) 
    {
        Delay_ms( 200 );
        bluetooth2_process();
        
        if ( strstr( app_buf, RSP_RING ) )
        {
            connection_flag = 1;
            send_cnt = 0;
        }
        if ( strstr( app_buf, RSP_NO_CARRIER ) )
        {
            connection_flag = 0;
            send_cnt = 0;
        }
        log_printf( &logger, "%s", app_buf );
        bluetooth2_clear_app_buf(  );
    }
    
    if ( connection_flag == 1 && send_cnt++ > SENDING_FREQ )
    {
        bluetooth2_generic_write( &bluetooth2, TEXT_TO_SEND, strlen( TEXT_TO_SEND ) );
        send_cnt = 0;
    }
    
    Delay_ms( 1 );
}

void main ( void ) 
{
    application_init( );

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

static void bluetooth2_clear_app_buf ( void ) 
{
    memset( app_buf, 0, app_buf_len );
    app_buf_len = 0;
    app_buf_cnt = 0;
}

static err_t bluetooth2_process ( void ) 
{
    int32_t rx_size;
    char rx_buff[ PROCESS_BUFFER_SIZE ] = { 0 };

    rx_size = bluetooth2_generic_read( &bluetooth2, rx_buff, PROCESS_BUFFER_SIZE );

    if ( rx_size > 0 ) 
    {
        int32_t buf_cnt = 0;

        if ( app_buf_len + rx_size >= PROCESS_BUFFER_SIZE ) 
        {
            bluetooth2_clear_app_buf(  );
            return BLUETOOTH2_ERROR;
        } 
        else 
        {
            buf_cnt = app_buf_len;
            app_buf_len += rx_size;
        }

        for ( int32_t rx_cnt = 0; rx_cnt < rx_size; rx_cnt++ ) 
        {
            if ( rx_buff[ rx_cnt ] != 0 ) 
            {
                app_buf[ ( buf_cnt + rx_cnt ) ] = rx_buff[ rx_cnt ];
            }
            else
            {
                app_buf_len--;
                buf_cnt--;
            }

        }
        return BLUETOOTH2_OK;
    }
    return BLUETOOTH2_ERROR;
}

static err_t bluetooth2_display_rsp ( uint16_t timeout )
{
    uint16_t timeout_cnt = 0;
    
    bluetooth2_process(  );
    
    while ( ( strstr( app_buf, RSP_OK ) == 0 ) && ( strstr( app_buf, RSP_READY ) == 0 ) && timeout_cnt++ < timeout )
    {
        bluetooth2_process(  );
        Delay_ms( 1 );
    }
    
    if ( app_buf_len > 0 )
    {
        for ( int32_t buf_cnt = 0; buf_cnt < app_buf_len; buf_cnt++ )
        {
            log_printf( &logger, "%c", app_buf[ buf_cnt ] );
        }
        bluetooth2_clear_app_buf(  );
        log_printf( &logger, "--------------------------------\r\n" );
        return BLUETOOTH2_OK;
    }
    return BLUETOOTH2_ERROR;
}

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

Additional Support

Resources

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