This board is a pure Bluetooth 2.1 audio receiver and comes without an audio amplifier. Optionally, it can be fitted with an infrared receptor and controlled by an external remote control.
Use it with the headphone jacks, or connect the stereo output to a dedicated external audio amplifier.
This module can be found by the names YTX888 and A7-004.
This board apparently uses a very old bluetooth 2.1 standard with limited RF power (1mW) and a distance of 1m indoor and 10m outdoor at 2.1MBit/s. Current bluetooth 5 standards send with up to 100mW and distances of 40m indoor and 200m outdoor at 50MBit/s. There may be board versions available that updated the bluetooth standard, however documentation does not tell.
Where To Use
This board handles Bluetooth audio reception and comes with built-in SD Card Reader slot. Since it is using the old Bluetooth 2.1 standard, the wireless distance is low, especially indoors. Use it only if you keep the sending bluetooth device (coupled smartphone) in immediate proximity (1-2m).
It can serve well in DIY Bluetooth Sound Boxes where you choose to use a separate dedicated audio amplifier.
Where To Avoid
If you are looking for a one-stop solution to creating a simple Bluetooth sound box, go get the integrated boards that come with 2x5W or 2x15W audio amplifiers on-board (XY-P5W or XY-P15W).
If you need to bridge larger distances, get a board with Bluetooth 5 standard.
Technical Data
| Item | Description |
|---|---|
| Power Supply | Micro USB or 5V, when VBAT pin present, also 3.7-4.2V |
| Audio Amplifier | no amplifier |
| Speaker Impedance | no speaker connections, just pins to connect to external amplifier |
| Audio In | Headphone Jack 3.5mm |
| Bluetooth Distance | <10m |
| Supported Sound File Formats | MP3, WMA, WAV, FLAC, APE |
| Size | 40x50x10mm with M3 mounting holes |
Power Supply
The board can be supplied with power via Micro USB or by supplying 5V to the power pins on the backside of the board.
Newer boards have a third solder pad labeled VBAT that can be used to directly power the board from a single LiIon or LiPo battery (3.7-4.2V).
Audio In
The board supports three different audio input souces:
- Bluetooth: pair the board with your smartphone or other source of audio
- SD Card: insert a SD Card into the built-in SD Card Reader (Micro-SD card format)
- USB Stick: use a USB-A Stick
Audio Out
Audio can be played to headphones via 3.5mm headphone jack, or by connecting the stereo output to an external amplifier.
You cannot directly connect speakers to this board as it does not have a built-in audio amplifier.
Operation
The board comes with five labeled buttons:
- MODE: Selects the audio source
- PLAY: Toggles play and pause
- NEXT: Short press: next title or next radio station. Long press increase volume
- BACK: Short press: previous title or next radio station. Long press decrease volume
- EQ: Equalizer: Classic, Jazz, Rock, Bass, Pop, Normal
FM Radio Reception
To use the built-in FM Radio receiver, make sure you added a wire to FM_ANT to serve as antenna. Without antenna, only very strong local FM stations can be received.
When a headphone is connected, its wire serves as antenna.
To set up FM radio reception, switch to radio mode and press PLAY for auto-tuning. Press EQ to store stations.
Additional Connectors
There are additional solder pads marked:
- MIC: connect a microphone as additional audio source
- MUTE: this port is low when no audio is played back and can be used to place external amplifiers into standby mode
- FM_ANT: connect a wire to serve as dedicated FM Radio Reception antenna
- Unmarked next to USB A: three pin connector can connect infrared diode (some packages ship with external IR remote control)
3D-Print
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(content created Apr 01, 2024 - last updated Apr 14, 2024)