Skip to main content

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:

void loop() if (bt.available()) Serial.write(bt.read());

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.

Common AT commands (entered after sending +++ with guard times before and after):

if (Serial.available()) bt.write(Serial.read());