Bluetooth 2 Click

How does it work?

Bluetooth 2 Click uses the WT41u, a fully integrated Bluetooth 2.1 + EDR, class 1 module combining antenna, Bluetooth radio, and an on-board iWRAP Bluetooth Stack. The WT41u is a replacement for the WT41. The WT41u provides a superior 110 dB link budget and more than 1000-meter line-of-sight connectivity for Bluetooth applications where extreme radio performance or reliability is required. It also constitutes an ideal solution for developers that want to quickly integrate extremely high performing Bluetooth wireless technology into their design without investing several months in Bluetooth radio and stack development. The WT41u uses Bluegiga's iWRAP Bluetooth stack, which is an embedded Bluetooth stack implementing 13 different Bluetooth profiles and Apple iAP connectivity. By using WT41u combined with iWRAP Bluetooth stack and Bluegiga's excellent technical support, designers ensure quick time-to-market, and low development costs and risks.

Targeted applications are Handheld terminals, Industrial devices, Point-of-Sale systems, PCs, Personal Digital Assistants (PDAs), Computer Accessories, Access Points, Automotive Diagnostics Units.

Bluetooth 2 Click uses a standard UART interface for communicating with other serial devices. Implemented WT41u module UART interface provides a simple mechanism for communicating with other serial devices using the RS232 protocol. Four signals are used to implement the UART function. When WT41u is connected to another digital device, UART_RX and UART_TX transfer data between the two devices. The remaining two signals, UART_CTS and UART_RTS, can be used to implement RS232 hardware flow control where both are active low indicators. All UART connections are implemented using CMOS technology and have signaling levels of 0V and VDD. UART configuration parameters, such as data rate and packet format, are set using WT41u software.

Besides the commonly used UART RX, TX, RTS, and CTS, Bluetooth 2 Click also has Reset, PIO7, and AIO pins, which are routed to the RST, PWM and AN pins of the mikroBUS™ socket, respectively. The SPI port can be used for system debugging. It can also be used for programming the Flash memory and setting the PSKEY configurations. WT41u uses 16-bit data and 16-bit address serial peripheral interface, where transactions may occur when the internal processor is running or is stopped. SPI interface is connected using the MOSI, MISO, CS, and SCK pins.

The communication interface can be selected by moving the SMD jumper designated as COM SEL to an appropriate position (CTS or CS) for RS232 or SPI protocol.

This Click Board™ is designed to be operated only with a 3.3V logic level. A proper logic voltage level conversion should be performed before the Click board™ is used with MCUs with different logic levels.

Specifications

Pinout diagram

This table shows how the pinout on Bluetooth 2 click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
Analog	AIO	1	AN	PWM	16	IO7	GPIO
Reset	RST	2	RST	INT	15	RTS	UART RTS
Chip Select	CS	3	CS	RX	14	TX	UART TX
SPI Clock	SCK	4	SCK	TX	13	RX	UART RX
SPI Data OUT	SDO	5	MISO	SCL	12	NC
SPI Data IN	SDI	6	MOSI	SDA	11	NC
Power Supply	3.3V	7	3.3V	5V	10	NC
Ground	GND	8	GND	GND	9	GND	Ground

Onboard settings and indicators

Bluetooth 2 Click electrical specifications

Software Support

We provide a library for the Bluetooth 2 Click on our LibStock page, as well as a demo application (example), developed using MikroElektronika compilers. The demo can run on all the main MikroElektronika development boards.

Library Description

The library covers all the necessary functions to control Bluetooth 2 Click board. A library performs the communication with the device via UART interface with WT41U-A Bluetooth 2 module.

Key functions:

• void bluetooth2_write_byte ( uint8_t input ) - Write Single Byte.
• uint8_t bluetooth2_read_byte ( void ) - Read Single Byte.
• void bluetooth2_uart_write ( uint8_t *tx_data ) - UART write function.

Examples description

The application is composed of three sections :

• System Initialization - Initializes peripherals and pins.
• Application Initialization - Initializes UART serial interface, UART interrupt, and write log.
• Application Task - (code snippet) - This function allows user to enter a commands, module configurations, data which will be transmitted, and also to check all module and connection status by using the serial terminal. Note: XX:XX:XX:XX:XX:XX replace with your device's Bluetooth address. Special commands: Press 'Enter' when you want to send the entered command (data). Press 'Backspace' to delete the wrong entered character before you send the command. Press 'Up-Down' or 'Left-Right' to see and enter a 3 last sent commands. Press 'Esc' and then 'r' character to perform a hardware reset via RST pin. The second segment allows user to read and check response from the SIM868 module when the response is ready.

void application_task ( )
{
    rx_dat = UART_Rdy_Ptr( );

    if ( rx_dat )
    {
        rx_dat = UART_Rd_Ptr( );

        check_rx( );
    }
}

Additional Functions :

• _strcpy - Allows user to copy content of one string to second string, starting from the first place.
• _strcmp - Allows user to compare a content of two selected strings.
• prev_cmd - Checks the character (Up, Down, Left, Right, Esc) that was entered by the user side.
• check_prev_cmd - Determines which of 3 previous entered commands will be entered again.
• exe_cmd - Compares an entered command with the predefined commands and if any of these commands is matched, then executes a desired operation.
• add_cmd_line - Adds a new command line for entering new data/command/request.
• check_rx - Executes a received character parsering, entered from the user side.

The full application code, and ready to use projects can be found on our LibStock page.

Other mikroE Libraries used in the example:

• UART
• Conversions

Additional notes and informations

Depending on the development board you are using, you may need USB UART click, USB UART 2 click or RS232 click to connect to your PC, for development systems with no UART to USB interface available on the board. The terminal available in all MikroElektronika compilers, or any other terminal application of your choice, can be used to read the message.

mikroSDK

This Click board™ is supported with mikroSDK - MikroElektronika Software Development Kit. To ensure proper operation of mikroSDK compliant Click board™ demo applications, mikroSDK should be downloaded from the LibStock and installed for the compiler you are using.

For more information about mikroSDK, visit the official page.