Bluetooth — Bl12-a3

| Parameter | Typical Value | |-----------|----------------| | Bluetooth Version | 5.0 (or 4.2) | | Supported Profiles | A2DP, AVRCP, HFP, HSP | | Audio Codec | SBC (possibly AAC) | | Operating Range | ≤10 meters (33 feet) line-of-sight | | Battery (if portable) | ~150–200 mAh (approx 6-8 hrs playtime) | | Input Voltage | 5V DC / 500mA |

Most BL12-A3 modules come with a 6-pin (2x3) or 4-pin header. The standard pinout is:

| Pin | Name | Description | |-----|---------|----------------------------------------| | 1 | VCC | Power input (3.3–5V) | | 2 | GND | Ground | | 3 | TXD | UART transmit (connects to MCU’s RX) | | 4 | RXD | UART receive (connects to MCU’s TX) | | 5 | STATE | Bluetooth connection status (HIGH when connected) | | 6 | EN/KEY | Enable / AT command mode trigger | bl12-a3 bluetooth

Note: Some modules label pin 5 as "LED" or "STAT" and pin 6 as "AT".

For a speaker that often retails between $15 and $30, the sound signature of the BL12-A3 is remarkably balanced. Manufacturers typically "smile" the EQ (boost bass and treble, scoop mids) to sound impressive in a store. The BL12-A3, however, takes a slightly flatter approach. Note: Some modules label pin 5 as "LED"

The Low End: Thanks to the dual passive radiators, the bass is punchy. Does it rattle your car windows? No. But for a compact speaker, the 80Hz roll-off is impressive. Acoustic bass and kick drums have weight.

The Mids: This is where budget speakers usually fail. Vocals get lost. The BL12-A3 keeps vocals forward. Podcasts and singer-songwriter tracks remain clear even at 70% volume. For a speaker that often retails between $15

The Highs: Cymbals and hi-hats are crisp without being sibilant (harsh 'S' sounds). There is no digital distortion in the upper register.

Maximum Volume: At 100% volume, there is noticeable compression, but no speaker breakup. It is loud enough to fill a small living room or a campsite.