BT122-A Click

How does it work?

BT122-A Click is based on the BT122-A, a dual-mode Bluetooth BR/EDR and BLE v4.2 module from Silicon Labs. This module is specifically designed for applications that demand Bluetooth Low Energy and Classic connectivity, offering communication with legacy devices supporting Bluetooth SPP or Apple® iAP2 profiles and modern devices that use Bluetooth Low Energy protocols. The BT122-A integrates a robust Bluetooth radio with up to +11dBm transmit power and -95dBm receive sensitivity, ensuring reliable communication over extended ranges. Additionally, the module features a built-in antenna and is powered by a low-power 32-bit ARM Cortex-M4 microcontroller, which, in combination with Silicon Labs’ Dual Mode stack software, provides exceptional processing efficiency and advanced connectivity capabilities.

The BT122-A is engineered to operate either as a standalone modem controlled by an external host MCU or as an independent application processor. For standalone operation, developers can use the integrated ARM Cortex-M4 MCU, enabling the embedding of applications using the Silicon Labs BGScript™ scripting language. This flexibility makes the module suitable for a wide range of use cases. Whether for cable replacement, HID devices, or advanced applications like health and fitness monitoring, industrial automation, M2M connectivity, or home automation gateways, the BT122-A Click delivers high performance and adaptability to meet diverse application requirements.

This Click board™ establishes communication between the BT122-A module and the host MCU through a UART interface, using standard UART RX and TX pins and hardware flow control via CTS and RTS pins. The default communication speed is set at 115200bps, ensuring efficient data exchange. The host MCU configures communication and other features using high-level AT commands, making it easy to manage without requiring in-depth knowledge of Bluetooth protocol. Additionally, the board includes an I2C interface with a maximum clock speed of 1MHz.

In addition to the interface pins, the board features a reset (RST) pin for hard-resetting the module when necessary and SWD pads designed for use with MIKROE’s 6-pin Needle Cable, providing an optional flash and debug SWD (Serial Wire Debug) interface functionality.

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. It also comes equipped with a library containing functions and example code that can be used as a reference for further development.

Specifications

Pinout diagram

This table shows how the pinout on BT122-A Click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
	NC	1	AN	PWM	16	NC
ID SEL	RST	2	RST	INT	15	RTS	UART RTS
UART CTS / ID COMM	CTS	3	CS	RX	14	TX	UART TX
	NC	4	SCK	TX	13	RX	UART RX
	NC	5	MISO	SCL	12	SCL	I2C Clock
	NC	6	MOSI	SDA	11	SDA	I2C Data
Power Supply	3.3V	7	3.3V	5V	10	NC
Ground	GND	8	GND	GND	9	GND	Ground

Onboard settings and indicators

BT122-A Click electrical specifications

Software Support

BT122-A Click demo application is developed using the NECTO Studio, ensuring compatibility with mikroSDK‘s open-source libraries and tools. Designed for plug-and-play implementation and testing, the demo is fully compatible with all development, starter, and mikromedia boards featuring a mikroBUS™ socket.

Example Description

This example demonstrates the use of BT122-A Click board by processing data from a connected BT device.

Key Functions

• bt122a_cfg_setup Config Object Initialization function.
• bt122a_init Initialization function.
• bt122a_set_local_name This function sets the local name of the device.
• bt122a_send_package This function sends a data package to the Click board.
• bt122a_read_package This function waits for the command or event type of message to arrive and then reads the complete message and stores it to the pkg structure.

Application Init

Initializes the driver and configures the Click board.

Application Task

Handles most of the events required for this example, the packages of events not supported in this example will just be displayed on the USB UART. The event handler will display all messages received from the remote device on the USB UART and echo the same message to the connected device.

Application Output

This Click board can be interfaced and monitored in two ways:

• Application Output – Use the “Application Output” window in Debug mode for real-time data monitoring. Set it up properly by following this tutorial.
• UART Terminal – Monitor data via the UART Terminal using a USB to UART converter. For detailed instructions, check out this tutorial.

Additional Notes and Information

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.