WT2003HM03 Voice Module
Compact UART‑Controlled Voice Module with SPI‑Flash, TF Card & USB Storage, Built‑in 0.5W Amp
The WT2003HM03 is the ultimate compact voice module in the HM series, offering triple storage support: SPI‑Flash up to 128Mbit, TF card up to 32GB, and USB drive up to 32GB. Powered by a 32‑bit processor up to 120MHz, it features 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 the most flexible voice module for applications requiring diverse storage options.
- 32‑bit processor – 120MHz for smooth playback
- Triple storage – SPI‑Flash + TF card + USB
- UART control – simple serial commands
- Built‑in 0.5W amp – direct speaker drive
- 32‑level volume – with power‑off memory
Storage Options – HM Series Comparison
| Module | Built‑in Flash | SPI‑Flash | TF Card | USB Drive |
|---|---|---|---|---|
| WT2003HM01 | 32Mbit | ✔ Up to 128Mbit | ✘ | ✔ Up to 32GB |
| WT2003HM02 | ✘ | ✘ | ✔ Up to 32GB | ✔ Up to 32GB |
| WT2003HM03 | ✘ | ✔ Up to 128Mbit | ✔ Up to 32GB | ✔ Up to 32GB |
WT2003HM03 is the most versatile option, supporting all three external storage media for maximum flexibility.
Key Features
UART Command Set
| Command | Function | Description |
|---|---|---|
| A0 | SPI‑Flash Index Playback | Play audio by index in SPI‑Flash root |
| A1 | SPI‑Flash Filename Playback | Play audio by filename in SPI‑Flash root (4‑byte name) |
| 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 |
| C3 | Query SPI‑Flash File Count | Get total audio files in SPI‑Flash |
| 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 Flash, TF, 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) |
| SPI‑Flash | Up to 128Mbit (FAT/FAT32) |
| 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 |
| 9/10 | DAC | DAC audio output (mono) |
| 11 | DM | USB D− |
| 12 | DP | USB D+ |
| 13 | SDDAT | SD card data |
| 14 | SDCMD | SD card chip select |
| 15 | SDCLK | SD card clock |
| 16 | VDDIO | 3.3V power output |
| 19 | AGND | Analog ground |
| 20 | ONEKEY | Next track button |
Application Scenarios
Why Choose WT2003HM03
Frequently Asked Questions
What storage media does WT2003HM03 support?
WT2003HM03 supports all three storage options: SPI-Flash up to 128Mbit, TF card (microSD) up to 32GB, and USB drive up to 32GB – all in FAT or FAT32 format. This makes it the most flexible module in the HM series.
What is the WT2003HM03 voice module?
WT2003HM03 is a compact voice playback module featuring a 32-bit processor (up to 120MHz), UART serial control, triple storage (SPI-Flash, TF card, USB), built-in 0.5W Class-D amplifier, and 32-level volume control.
What audio formats are supported?
WT2003HM03 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 WT2003HM03 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. It 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 module operates from 2.6V to 5.0V, with ripple controlled within 5% and peak voltage below 5.5V.
What is the module size?
The module measures 21.01mm × 18.21mm with 2.0mm pin spacing, making it suitable for compact designs.
Can I update audio files via USB?
Yes. Connect the module to a PC via USB, and all connected storage media appear as removable drives. Copy audio files directly, then disconnect USB before sending serial commands.
What are the typical applications?
Voice prompt systems, home appliances, automotive electronics, toys, industrial alarms, consumer electronics, and any application requiring flexible voice playback with multiple storage options.
Important: The module supports FAT and FAT32 formats only. For SPI‑Flash, Waytronic‑branded Flash is recommended for guaranteed compatibility. 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.
