HC-02 Bluetooth 2.0 Serial Module (UART)

Connect the HC-02's VCC pin to Arduino's 5V or 3.3V pin (within 3.2-6V range), GND to GND, TX to Arduino's RX (Pin 0), and RX to Arduino's TX (Pin 1). Use a voltage divider or logic level converter if your Arduino operates at 3.3V to ensure safe signal levels. The module's default baud rate is 9600, which you must set in your Serial.begin(9600) command. The status LED will blink rapidly until paired, then stay solid.

The default pairing PIN for the HC-02 is '1234'. To change it, you must enter AT command mode. Typically, this involves pulling the module's KEY pin high (to VCC) before power-up, then sending 'AT' commands via a serial terminal at 38400 baud. Use the command 'AT+PSWD=xxxx' to set a new four-digit PIN. Ensure you save the settings with 'AT+SAVE' before exiting. Not all HC-02 variants support AT commands; check your supplier's documentation.

Yes, the HC-02 can pair with an HC-05 module configured as a master device. First, set the HC-05 to master mode using AT commands (AT+ROLE=1 and AT+CMODE=0). Power the HC-02 in slave mode (its default state). Put the HC-05 in pairing mode to search for and connect to the HC-02's MAC address or name. Once paired, data sent via UART to one module will be transmitted wirelessly and output from the other's UART TX pin, creating a transparent serial link.

The HC-02, using Bluetooth 2.0+EDR, supports a maximum theoretical data rate of up to 3 Mbps. However, in practical UART serial applications, the effective throughput is limited by the configured baud rate. At its default 9600 baud, you can achieve approximately 960 bytes per second. You can increase the baud rate via AT commands (e.g., AT+UART=115200,0,0) for higher speed, but stability may decrease with distance. For consistent performance over its ~10m range, 115200 baud is a common reliable maximum.