WT2003HM02 Voice Module
Compact UART‑Controlled Voice Module with TF Card & USB Storage, Built‑in 0.5W Amp
The WT2003HM02 is a compact, high‑performance voice module featuring TF card (microSD) and USB drive storage for flexible audio content management. Powered by a 32‑bit processor up to 120MHz, it supports 32‑level volume control, a built‑in 0.5W Class‑D amplifier, and a simple UART command set (default 9600 baud). With USB mass storage emulation for drag‑and‑drop audio file management, it is ideal for voice prompt systems, home appliances, and industrial equipment requiring removable storage.
- 32‑bit processor – 120MHz for smooth playback
- TF card & USB – up to 32GB each
- UART control – simple serial commands
- Built‑in 0.5W amp – direct speaker drive
- 32‑level volume – with power‑off memory
Key Features
UART Command Set
| Command | Function | Description |
|---|---|---|
| A2 | TF Card Index Playback | Play audio by index in TF card root |
| A3 | TF Card Filename Playback | Play audio by filename in TF card root (4‑byte name) |
| A4 | TF Card Folder Index Playback | Play audio by index in TF card folder (5‑char folder name) |
| A6 | USB Index Playback | Play audio by index in USB drive root |
| A7 | USB Filename Playback | Play audio by filename in USB drive root (4‑byte name) |
| A8 | USB Folder Index Playback | Play audio by index in USB folder (5‑char folder name) |
| A9 | USB Folder Filename Playback | Play audio by filename in USB folder |
| AA | Pause / Resume | Toggle pause/playback |
| AB | Stop | Stop current playback |
| AC | Next Track | Play next track |
| AD | Previous Track | Play previous track |
| AE | Volume Control | Set volume (0–31, with power‑off memory) |
| AF | Playback Mode | Normal / Single loop / All loop / Random |
| B1 | Insert Playback | Insert a track during current playback |
| B6 | Output Mode Switch | Switch between PWM (SPK) and DAC |
| C1 | Query Volume | Read current volume level |
| C2 | Query Work Status | Play / Stop / Pause |
| C5 | Query TF Card File Count | Get total audio files in TF card |
| C6 | Query TF Card Folder File Count | Get audio file count in TF card folder |
| C7 | Query USB File Count | Get total audio files in USB drive |
| C8 | Query USB Folder File Count | Get audio file count in USB folder |
| C9 | Query Current Track | Get current playback track address |
| CA | Query Peripheral Status | Check TF card, USB, and PC connection status |
| CB | Query Current Song Name | Get filename of current playback |
Protocol format: 7E + Length + Command + Parameters + Checksum + EF. Checksum is the low byte of (Length + Command + Parameters) sum.
Technical Specifications
| Parameter | Value / Condition |
|---|---|
| Processor | 32‑bit, up to 120MHz |
| Operating Voltage | 2.6V – 5.0V (ripple <5%, peak <5.5V) |
| TF Card | Up to 32GB (FAT/FAT32) |
| USB Drive | Up to 32GB (FAT/FAT32) |
| Audio Formats | MP3, WAV (8–44.1kHz, mono 8–320kbps, stereo ≤128kbps) |
| Audio Output | PWM (0.5W Class‑D) / DAC |
| Volume Levels | 32 (0–31, with power‑off memory) |
| Playback Modes | Normal, Single loop, All loop, Random |
| Control Interface | UART (default 9600 baud) |
| Peripherals | I2C, PWM, Infrared decoder, 16‑bit ADC/DAC |
| IO Drive Capability | Up to 64mA |
| Operating Temperature | ‑40°C ~ +85°C |
| Module Size | 21.01 × 18.21mm |
| Pin Pitch | 2.0mm |
Key Pin Functions (20‑Pin Module)
| Pin | Name | Function |
|---|---|---|
| 2 | VBAT | Power input (2.6–5.0V) |
| 3 | TXD | UART transmit |
| 4 | RXD | UART receive |
| 5 | BUSY | Busy signal output (high during playback) |
| 6 | ADKEY | Analog key input |
| 7 | SPK+ | Speaker positive terminal |
| 8 | SPK− | Speaker negative terminal |
| 9 | DACR | DAC right channel output |
| 10 | DACL | DAC left channel output |
| 11 | DM | USB D− |
| 12 | DP | USB D+ |
| 13 | SD_DAT | SD card data |
| 14 | SD_CMD | SD card chip select |
| 15 | SD_CLK | SD card clock |
| 16 | VDDIO | 3.3V power output |
| 19 | AGND | Analog ground |
| 20 | ONEKEY | Next track button |
Application Scenarios
Why Choose WT2003HM02
Frequently Asked Questions
What is the WT2003HM02 voice module?
It is a compact voice playback module featuring a 32-bit processor (up to 120MHz), UART serial control, TF card and USB storage support, built-in 0.5W Class-D amplifier, and 32-level volume control.
What storage options are supported?
WT2003HM02 supports TF card (microSD) up to 32GB and USB drives up to 32GB, both in FAT or FAT32 format. Both can be accessed as removable drives via the USB interface.
What audio formats are supported?
WT2003HM02 supports MP3 and WAV formats with sampling rates from 8kHz to 44.1kHz. Mono audio supports 8–320kbps, stereo supports up to 128kbps.
How do I control the module?
The WT2003HM02 module uses a standard UART serial interface with default baud rate 9600. Commands follow a 7E … EF protocol for playback, volume, mode, and query operations.
Does it have a built-in amplifier?
Yes. WT2003HM02 features a built-in 0.5W Class-D amplifier with PWM output. DAC output is also available with a command switch (B6).
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 is the operating voltage range?
The WT2003HM02 module operates from 2.6V to 5.0V, with ripple controlled within 5% and peak voltage below 5.5V.
Can I update audio files via USB?
Yes. Connect the module to a PC via USB, and the TF card appears as a removable drive. Copy audio files directly, then disconnect USB before sending serial commands.
What is the module size?
The module measures 21.01mm × 18.21mm with 2.0mm pin spacing, making it suitable for compact designs.
What are the typical applications?
Voice prompt systems, home appliances, automotive electronics, toys, industrial alarms, consumer electronics, and any application requiring removable TF card storage for easy audio updates.
Important: The module supports FAT and FAT32 formats only. After copying audio files via USB, disconnect the USB cable before sending UART commands. The BUSY pin is low in idle and high during playback. When switching audio output modes (B6), wait 200ms before sending other commands. File indexing is based on copy order, not filename. Command interval between each command string should be 200–300ms.
