Bl12-a3 Bluetooth Apr 2026
1. Introduction The BL12-A3 is a compact, low-power, and highly integrated Bluetooth 4.0 (BLE) module designed for short-range wireless communication. It is widely adopted in Internet of Things (IoT) projects, smart home devices, wireless sensor networks, and educational microcontroller prototyping. The module acts as a transparent serial data bridge, converting UART (Universal Asynchronous Receiver-Transmitter) signals to Bluetooth signals and vice versa. This makes it exceptionally easy to use with platforms like Arduino, ESP32, STM32, and Raspberry Pi.
void loop() if (bt.available()) Serial.write(bt.read());
void setup() Serial.begin(9600); bt.begin(9600); // Match BL12-A3 default baud Serial.println("BL12-A3 ready"); bl12-a3 bluetooth
Common AT commands (entered after sending +++ with guard times before and after):
if (Serial.available()) bt.write(Serial.read()); The module acts as a transparent serial data
Always verify your vendor’s datasheet, as pin assignments and command sets may vary slightly between manufacturers. When in doubt, start with the factory default 9600 baud and use a USB-to-TTL adapter to test the module independently before integrating it into a larger system. End of write-up.
| Command | Description | Example Response | |---------|-------------|------------------| | AT | Check communication | OK | | AT+NAME=<name> | Set device name | OK | | AT+BAUD=<param> | Change baud rate (1=9600,2=19200,4=38400,5=57600,6=115200) | OK | | AT+ROLE=<mode> | 0=Slave, 1=Master | OK | | AT+ADDR? | Query module’s MAC address | +ADDR:xx:xx:xx:xx:xx:xx | | AT+RENEW | Restore factory settings | OK | Note: After changing baud rate, your serial terminal must match the new rate before further commands. | Feature | BL12-A3 | HC-05 | HC-06 | HM-10 | |---------|---------|-------|-------|-------| | Bluetooth Classic/BLE | BLE 4.0 | Classic 2.0 | Classic 2.0 | BLE 4.0 | | Master/Slave Capable | Slave (optional master firmware) | Both | Slave only | Both | | AT Command Mode | Yes | Yes | Limited | Yes | | Default Baud Rate | 9600 | 9600 | 9600 | 9600 | | Typical Cost | ~$3–5 | ~$6–8 | ~$4–6 | ~$8–10 | | iOS/Android App Support | BLE apps | Classic SPP apps | Classic SPP apps | BLE apps | When in doubt, start with the factory default
Its popularity stems from its balance of cost, performance, and simplicity—offering reliable wireless connectivity without requiring deep expertise in RF engineering or Bluetooth protocol stacks. | Parameter | Value / Range | |-----------|----------------| | Bluetooth Version | 4.0 (BLE - Bluetooth Low Energy) | | Frequency Band | 2.4 GHz ISM (2402–2480 MHz) | | Transmit Power | -20 dBm to +4 dBm (configurable) | | Receiver Sensitivity | -93 dBm (typical) | | Operating Voltage | 3.0V – 3.6V (3.3V nominal, NOT 5V tolerant ) | | Current Consumption | Standby: ~1.5 µA Active (Tx/Rx): 8–15 mA | | Data Rate | UART: 9600 bps (default), up to 115200 bps BLE: 1 Mbps | | Interface | UART (Tx, Rx), RTS/CTS (optional flow control) | | Range (open air) | 10–30 meters (class 2 device) | | Antenna | Onboard PCB trace antenna | | Dimensions | Approx. 27 mm × 13 mm × 2 mm | | Operating Temperature | -20°C to +70°C | 3. Pinout Description The BL12-A3 typically exposes 6 pins (through 0.1″ pitch headers), though some variants include extra pins for status LEDs or reset. The standard pinout is:
