WT2801A-32N Bluetooth Audio Chip
Low‑Power Bluetooth Audio with BLE 5.4 + 2.4GHz, Built‑in 0.5W Amp & OTA Voice Update
The WT2801A-32N is a high‑performance, low‑power Bluetooth audio chip featuring a 32‑bit DSP running at up to 240MHz. It supports BLE 5.4 transparent transmission and a unique 2.4GHz broadcast mode for one‑to‑many OTA voice updates within 10 meters. With a built‑in 0.5W Class‑D amplifier (320mW @ 8Ω), 16‑bit DAC (91dB SNR) and 16‑bit ADC (95dB SNR), it delivers high‑quality audio while reducing external components. Supporting SPI‑Flash, TF card, and USB drive storage with UART command control, it is ideal for Bluetooth speakers, smart home devices, and field‑updatable voice systems.
- 240MHz DSP – high‑performance audio processing
- BLE 5.4 + 2.4GHz – dual‑mode wireless
- Built‑in 0.5W amp – 320mW @ 8Ω, Class‑D
- 2.4GHz OTA update – one‑to‑many voice replacement
- 16‑bit DAC/ADC – 91dB / 95dB SNR
Key Features
2.4GHz Broadcast OTA Voice Update
One‑to‑Many Broadcasting
A single USB 2.4GHz transmitter (with TF card) can broadcast voice/firmware .bin files to multiple WT2801A-32N chips simultaneously within 10 meters.
Simple Field Updates
Store the .bin file on the TF card, press the transmitter button to start broadcasting. Chips entering 2.4G mode (FF00FC command) will receive and update automatically.
File Size Support
Supports .bin files up to 100KB. After successful update, chips reset and exit 2.4G mode automatically.
UART Command Highlights
| Command | Function | Description |
|---|---|---|
| FF 00 A0 | Index Playback | Play audio by Flash index (0000–FFFF) |
| FF 00 AA | Pause / Resume | Toggle pause/playback |
| FF 00 AB | Stop | Stop current playback |
| FF 00 AC / AD | Next / Previous | Track navigation |
| FF 00 AE | Volume Control | Set volume (0–31, with memory) |
| FF 00 AF | Playback Mode | Normal / Single loop / All loop / Random |
| FF 00 B0 | Combo Playback | Play up to 35 tracks in sequence |
| FF 00 B1 | Insert Playback | Insert a track during playback |
| FF 00 B8 | Low Power | Deep sleep (5µA) / Standby (30µA) |
| FF 00 BF | BUSY Mode Switch | Configurable BUSY polarity |
| FF 00 FB | Baud Rate Change | 11 fixed baud rates (2400–921600) |
| FF 05 01–19 | BLE Commands | Transparent transmission, name, address, power, broadcast |
| FF 00 FC | Enter 2.4G Mode | Enter OTA broadcast receive mode |
| FF 00 FD | Exit 2.4G Mode | Exit OTA mode (if not in update) |
Technical Specifications
| Parameter | Value / Condition |
|---|---|
| Package | QFN32 (4×4mm) |
| Processor | 32‑bit DSP, up to 240MHz |
| Operating Voltage | 2.7V – 5.0V |
| Wireless | BLE 5.4 + 2.4GHz broadcast |
| Built‑in Amplifier | Class‑D, 320mW @ 8Ω |
| DAC Resolution | 16‑bit, 91dB SNR |
| ADC Resolution | 16‑bit, 95dB SNR |
| Audio Formats | MP3, WAV (8–44.1kHz, 8–320kbps) |
| Storage Media | SPI‑Flash (128Mbit), TF (32GB), USB (32GB) |
| Control Interface | UART (9600 default, configurable) |
| Volume Levels | 32 (0–31, with power‑off memory) |
| Deep Sleep Current | < 5 µA |
| Standby Current | < 30 µA |
| Operating Temperature | ‑20°C ~ +85°C |
| Storage Temperature | ‑65°C ~ +150°C |
| IO Drive Capability | Up to 8mA |
Key Pin Functions (QFN32)
| Pin | Name | Function |
|---|---|---|
| 0 (PAD) | GND | Thermal pad – must be grounded |
| 5 | RXD | UART receive |
| 6 | PWM− | Speaker negative terminal |
| 7 | PWM+ | Speaker positive terminal |
| 8 | VCC | Power input (2.7–5.0V) |
| 9 | VOUT | 3.3V LDO output (1µF cap to ground) |
| 10 | TXD | UART transmit |
| 16 | ANT | Bluetooth antenna |
| 17 | OSCI | Crystal input (24MHz, 12pF) |
| 18 | OSCO | Crystal output |
| 22 | BUSY | Busy signal output |
| 23 | DM | USB D− / Programming |
| 24 | DP | USB D+ / Programming |
| 28 | AGND | Analog ground |
| 29 | MIC+ | Microphone input |
| 30 | MICLDO | MIC power supply |
| 32 | DAC | DAC audio output |
Application Scenarios
Why Choose WT2801A-32N
Frequently Asked Questions
What is the WT2801A-32N?
WT2801A-32N is a low-power Bluetooth audio chip with a 32-bit DSP up to 240MHz, BLE 5.4 + 2.4GHz dual-mode, built-in 0.5W Class-D amplifier, 16-bit DAC/ADC, and UART command control in a compact QFN32 package.
What are the wireless capabilities?
It supports BLE 5.4 transparent transmission and 2.4GHz broadcast mode. The 2.4GHz mode enables one-to-many OTA voice updates for firmware and voice content replacement.
What storage media are supported?
It supports SPI-Flash up to 128Mbit, TF card up to 32GB, and USB drive up to 32GB. Audio files can be played from any of these storage media.
Does it have a built-in amplifier?
Yes. It features a built-in 16-bit Class-D amplifier delivering 320mW into an 8Ω speaker, enabling direct speaker drive without external amplifier ICs.
What audio formats are supported?
It supports MP3 and WAV formats with bitrates from 8kbps to 320kbps, delivering high-quality audio playback.
How is the chip controlled?
It uses a standard UART interface with default baud rate 9600, configurable up to 921600. Commands follow a 7E … EF protocol for playback, volume, mode, BLE, and 2.4G control.
What is the operating voltage range?
The chip operates from 2.7V to 5.0V, compatible with both 3.3V and 5V systems.
What is unique about the 2.4G broadcast mode?
The 2.4G broadcast mode allows a single transmitter (with TF card) to update multiple chips simultaneously within 10 meters, enabling efficient field upgrades of firmware and voice content.
How many volume levels are available?
32 levels (0 to 31), with 0 = mute and 31 = maximum volume. The setting has power-off memory.
What are the typical applications?
Bluetooth speakers, voice prompt devices, smart home controllers, wearable devices, shared devices, toys, industrial alarms, and any application requiring low-power Bluetooth audio with field-updatable voice content.
Important: A 24MHz crystal (12pF, ±10PPM) is required for Bluetooth operation. The bottom pad (pin 0) must be grounded. 2.4G broadcast mode supports .bin files up to 100KB – ensure the file size is within this limit. The chip defaults to Bluetooth mode on power‑up. For external Flash, Waytronic‑branded Flash is recommended. Capacitors must be placed close to the VCC and VOUT pins.
