HC-02 Bluetooth serial communication module is based on the Bluetooth V2.0 Bluetooth protocol data transmission module, high stability, ultra low power consumption, industrial grade Bluetooth data transmission module.

Users do not need to care about complex wireless communication configuration and transmission algorithms. They only need to connect to devices through TTL serial port. Powered the HC-02 slave module, and can be connected to the mobile phone for data transmission. In addition, it can be used with HC-05 or HC-06 hosts
(matching code, default is 1234) to connect, can replace a traditional serial line, save wiring work, use
It’s very flexible.

If you need to use iphone or ipad to control your for Arduino project, hc-02 4.0 ble slave module with 6pin baseboard may be a good choice.Fully compatible with ios7.0 or later.Also compatible with Android 4.3 or later.

Please note:
If the version of the Android os is less than 4.3. it is not compatible.
This module supports bluetooth 4.0 ble mode and bluetooth 2.0 mode.

If you are not so familiar with the Bluetooth, you can get more info about blutooth from here.


 Model HC-02 Module size 27*13mm
Work band  2.4G Air rate 2Mbps
Communication interface UART3.3V TTL Antenna interface built-in PCB antenna
Working voltage 3.0~3.6V Communication current 30mA
Baud rate 1200~115200bps Receiver sensitivity -85dBm@2Mbps
Communication level 3.3V Working humidity 10%~90%
The transmitting power 6dBm (maximum) Storage temperature -40 C ~+85 C
Reference distance 10m Working temperatur -25 C ~75 C
  1. Core module uses HC-08, leads from the module interface includes VCC, GND, TXD, RXD, LED status output pin.
  2. Led indicate Bluetooth connection status, flashing Bluetooth connectivity, lit the Bluetooth connection and open a port Backplane
  3. 3.3V LDO input voltage 3.6 6V, the input voltage to prohibit more than 7V
  4. The interface level 3.3V, can be directly connected the various SCM (51, AVR, PIC, ARM, MSP430, etc.), the 5V MCU also can be connected directly.
  5. Open to the effective distance of 10 meters, over 10 meters is also possible, but not of this the quality of the connection of the distance do to ensure.
  6. After the pair when full-duplex serial port to use, do not need to know anything about the Bluetooth protocol, but only supports 8 data bits, 1 stop bit, no parity communication format, which is the most commonly used communication format does not support other formats .
  7. Compact (3.57cm * 1.52cm), the factory chip production to ensure the placement quality. And sets of transparent heat shrink tubing, dust and beautiful, and anti-static.

Pin Configuration

Pin Number Pin Name Description
1 Enable / Key This pin is used to toggle between Data Mode (set low) and AT command mode (set high). By default it is in Data mode
2 Vcc Powers the module. Connect to +5V/+3.3V Supply voltage
3 Ground Ground pin of module, connect to system ground.
4 TX – Transmitter Transmits Serial Data. Everything received via Bluetooth will be given out by this pin as serial data.
5 RX – Receiver Receive Serial Data. Every serial data given to this pin will be broadcasted via Bluetooth
6 State The state pin is connected to on board LED, it can be used as a feedback to check if Bluetooth is working properly.
7 LED Indicates the status of Module

  • Blink once in 2 sec: Module has entered Command Mode
  • Repeated Blinking: Waiting for connection in Data Mode
  • Blink twice in 1 sec: Connection successful in Data Mode

Where to use HC-02 Bluetooth module

The HC-02 is a very cool module which can add two-way (full-duplex) wireless functionality to your projects. You can use this module to communicate between two microcontrollers like for Arduino or communicate with any device with Bluetooth functionality like a Phone or Laptop. There are many android applications that are already available which makes this process a lot easier.It’s also fully compatible with the iPhone. The module communicates with the help of USART at 9600 baud rate hence it is easy to interface with any microcontroller that supports USART. We can also configure the default values of the module by using the command mode. So if you looking for a Wireless module that could transfer data from your computer or mobile phone to microcontroller or vice versa then this module might be the right choice for you.

However do not expect this module to transfer multimedia like photos or songs; you might have to look into the CSR8645 module for that.

How to Use the HC-02 Bluetooth module

The HC-02 has two operating modes, one is the Data mode in which it can send and receive data from other Bluetooth devices and the other is the AT Command mode where the default device settings can be changed. We can operate the device in either of these two modes by using the key pin as explained in the pin description.

It is very easy to pair the HC-02 module with microcontrollers because it operates using the Serial Port Protocol (SPP). Simply power the module with +5V/+3.3V and connect the Rx pin of the module to the Tx of MCU and Tx pin of module to Rx of MCU as shown in the figure below

During power up the key pin can be grounded to enter into Command mode, if left free it will by default enter into the data mode. As soon as the module is powered you should be able to discover the Bluetooth device as “HC-02” then connect with it using the default password 1234 and start communicating with it.

Working principle

Connect with MCU

Connect with another Blutooth module

HC-06 is the host, HC-02 is slave, the matching code is consistent (the default is 1234), the baud rate is the same,  then power on can be automatically connected. After the first connection, the HC-06 host will automatically match the matching objects. If you want to connect to other modules, you must first remove the pairing memory of the HC-06 host. There is no matching memory from the slave.

Connect with Android phone

HC-02 can be connected to Android mobile via Bluetooth, and Android can use Android serial assistant software.

Connect with iPhone

HC-02 can be connected to iPhone 4S and later version iPhone . Communication test needs to download and install BLE serial assistant software.
Proprietary Service UUID: 49535343-FE7D-4AE5-8FA9-9FAFD205E455
TX UUID: 49535343-1 E4D-4BD9-BA61-23C647249616
RX UUID: 49535343-8841-43F4-A8D4-ECBE34729BB3

Connect with PC

HC-02 can connect to a computer via the HC-06-USB Bluetooth virtual serial port.
HC-02 can connect to the computer’s Bluetooth device to communicate.


1. Wireless communication between two microcontrollers

2. Communicate with Laptop, Desktops and mobile phones

3. Data Logging application

4. Consumer applications

5. Wireless Robots

6. Home Automation

AT Command

The way to the AT command mode: supply power to the module, it will enter to the AT mode if it
needn’t pair. The interval of command is about 1 second.
Default parameter: Baud rate:9600N81, ID: linvor, Password:1234

1. Test communication

Send: AT (please send it every second)
Back: OK

2. Reset the Bluetooth serial baud rate

Send: AT+BAUD1
Back: OK1200
Send: AT+BAUD2
Back: OK2400
4———9600 (Default)
PC can’t support the baud rate lager than 115200. The solution is: make the MCU have higher baud
rate (lager than 115200) through programming, and reset the baud rate to low level through the AT
The baud rate reset by the AT command can be kept for the next time even though the power is cut

3. Reset the Bluetooth name

Send: AT+NAMEname
Back: OKname


Send: AT+NAMEosoyoo
Back: OKname

At this time the Bluetooth name is changed to “osoyoo”.

4. Change the Bluetooth pairing password

Send: AT+PINxxxx

Back: OKsetPIN

More info about the AT Command please check this link.