Offline AI Voice & Speech Recognition Module for Arduino/ESP32
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The Gravity Offline Speech Recognition Module is a highly efficient, plug-and-play offline voice recognition solution designed for advanced human-computer interaction, voice assistants, smart home automation, and educational AI projects. As an offline speech recognition module, it operates entirely without an internet connection, ensuring maximum data privacy and security for all your voice control applications. Fully compatible with popular development platforms like Arduino UNO, micro:bit, and ESP32, this AI voice module includes detailed tutorials to help you implement offline voice control quickly.
Key Features of the Offline Voice Recognition Module
- Plug and Play Compatibility: This offline speech recognition module works seamlessly with Arduino UNO, micro:bit, and ESP32 via I2C/UART communication.
- 121 Built-in Voice Commands: Pre-programmed for immediate offline voice interaction without any complex configuration.
- 17 Custom Commands via Self-Learning: Teach your offline voice recognition module new commands using your own voice. Supports any language or sound trigger.
- Offline Operation: No network required, ensuring superior privacy and AI speech recognition functionality in low-connectivity environments.
- Compact and Integrated Design: Features a built-in microphone and speaker to simplify wiring for Arduino voice projects.
- Real-Time Voice Feedback: Provides instant audible feedback to improve the human-machine interaction experience.
Applications
- Voice-controlled smart home devices and automated lighting
- Educational STEM and AI speech recognition projects
- Advanced human-machine interaction for robotics
- Prototyping for hardware competitions using Arduino or ESP32
- Pet care automation and environmental voice triggers

Technical Specifications
- Operating Voltage: 3.3V - 5V (Perfect for Arduino and micro:bit)
- Maximum Operating Current: < 370 mA (5V)
- Communication Interface: I2C / UART
- I2C Address: 0x64
- Fixed Commands: 121 Pre-set speech recognition words
- Fixed Wake Word: 1
- Custom Commands: 17 Self-learned commands
- Microphone Sensitivity: -28dB
- Module Dimensions: 49 × 32 mm / 1.93" × 1.26"
- Operating Temperature: 0°C to 70°C
Self-Learning AI Function
This offline voice recognition module features a user-friendly self-learning mode. Teach the AI speech module any word or sound by speaking the command three times; it will automatically store the acoustic model for future recognition. This allows for multilingual voice control or unique sound triggers:
- “Meow” – triggers a smart pet feeder
- “Limpia” – controls a cleaning robot (Spanish for “clean”)
- “Snap” – activates a voice-triggered camera

Secure Offline Usage and Privacy
Unlike cloud-based assistants, this offline speech recognition solution ensures no data is sent to the internet. This makes it the ideal voice recognition module for privacy-sensitive environments like schools, labs, or secure home automation systems.
Real-Time Feedback and Interaction
The integrated AI voice module provides instant audio confirmation, which is essential for debugging Arduino voice control code and ensuring a smooth user experience in real-world deployments.

Package Includes
- 1× Gravity Offline Voice Recognition Module
- 1× Jumper wire set (Gravity compatible)
- Access to online Arduino and ESP32 tutorials
Real-World Applications & Tutorials
Project: Create a Voice-Controlled SOS Alert System
Learn how to build an offline voice-activated SOS system using this module with M5StickC. Perfect for smart home safety, showing how voice recognition can trigger emergency alerts.
Review: Exploring the Gravity Voice Recognition Module
Discover why this offline voice module is praised for its reliability in automation. It enables seamless voice control for Arduino without any internet dependency.
Project: Mastering Voice Commands with Arduino
A comprehensive guide on integrating offline speech recognition with Arduino UNO. Learn how to set up custom AI voice commands for interactive projects.
Project: Raspberry Pi Pico Voice Control Guide
Unlock the potential of Raspberry Pi Pico with offline voice recognition. This guide covers hardware setup and executing speech recognition triggers for smart control.
Reference & Resources
Product Wiki | Command Words List | Interface Diagram | Arduino Tutorial | MakeCode Tutorial
1. General Shipping Information
- We provide reliable shipping services with a tracking number for each order.
- Shipping addresses must be entered in English and should not contain special symbols, so that the courier system can recognize your location correctly.
- Please make sure your shipping address is accurate before placing your order. We ship strictly according to the address provided at checkout.
- In-stock orders are usually dispatched within 1 business day after order confirmation.
- Estimated delivery times refer to the period after dispatch and do not include order processing time, weekends, public holidays, customs inspection, or force majeure delays.
- If you need to cancel or modify your order, please contact us before the order is marked as “Shipped”. Once shipped, the order cannot be canceled or changed.
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If you require expedited shipping, please contact our customer support team at info@upenelab.com for a customized quote based on your destination.
2. Shipping Rates & Options
Shipping rates are calculated based on order value, destination, and available shipping methods. The final available options will be displayed at checkout.
2.1 Germany Domestic Shipping
| Shipping Method | Order Value | Cost | Est. Delivery |
|---|---|---|---|
| Deutsche Post | €0.00 - €50.00 | €4.95 | 2-4 Business Days |
| Deutsche Post | Over €50.00 | Free | 2-4 Business Days |
|
DHL Paket (Faster Delivery) |
€0.00 - €50.00 | €6.95 | 1-3 Business Days |
|
DHL Paket (Faster Delivery) |
€50.00 - €100.00 | €2.00 | 1-3 Business Days |
|
DHL Paket (Faster Delivery) |
Over €100.00 | Free | 1-3 Business Days |
2.2 Selected EU Countries / Regions
Available EU shipping destinations are shown at checkout based on your shipping address. For orders shipped to selected EU countries or regions outside Germany, we use FedEx Regional Economy.
| Shipping Method | Order Value | Cost | Est. Delivery |
|---|---|---|---|
| FedEx Regional Economy | €0.00 - €100.00 | €7.95 | 3-5 Business Days |
| FedEx Regional Economy | Over €100.00 | Free | 3-5 Business Days |
EU orders may be fulfilled from our Munich warehouse or, when applicable, from our Shenzhen warehouse depending on inventory availability. For EU member states, OpenELAB covers applicable import duties and taxes under DDP service where required.
2.3 United States
| Region | Shipping Method | Order Value | Cost | Est. Delivery |
|---|---|---|---|---|
|
Continental U.S. (50 States) |
USPS Ground Advantage | €0.00 - €45.00 | €4.95 | 3-7 Business Days |
| USPS Ground Advantage | Over €45.00 | Free | 3-7 Business Days | |
| USPS Priority Mail | €0.00 - €45.00 | €16.95 | 1-4 Business Days | |
| USPS Priority Mail | Over €45.00 | €14.95 | 1-4 Business Days | |
|
Non-Continental U.S. (AK, HI, PR, etc.) |
USPS Ground Advantage | €0.00 - €60.00 | €6.95 | 5-9 Business Days |
| USPS Ground Advantage | Over €60.00 | Free | 5-9 Business Days |
Non-Continental U.S. regions include Alaska, American Samoa, Guam, Hawaii, the Marshall Islands, the Northern Mariana Islands, Palau, Puerto Rico, the U.S. Virgin Islands, and U.S. Armed Forces addresses.
2.4 International Destinations Outside the EU
For selected international destinations outside the EU, including Switzerland, the United Kingdom, and Norway, shipping rates are as follows:
| Order Amount | Shipping Cost |
|---|---|
| €0.00 - €300.00 | €19.95 |
| Over €300.00 | Free |
For non-EU destinations, import duties, taxes, and customs fees may be charged by the destination country and are the responsibility of the recipient.
3. Warehouses & Fulfillment
Our products may be stored in our Munich, Arlington, and Shenzhen warehouses. The actual shipping warehouse depends on product availability and destination.
3.1 Munich Warehouse
For products stored in our Munich warehouse, we use Deutsche Post or DHL Paket for domestic deliveries within Germany. For selected EU destinations outside Germany, we use FedEx Regional Economy.
3.2 Arlington Warehouse
For products stored in our Arlington warehouse, we use USPS or UPS for deliveries within the United States.
3.3 Shenzhen Warehouse
For pre-order items or products fulfilled directly from our Shenzhen warehouse, we arrange reliable international shipping based on destination and inventory status. For EU member states, OpenELAB covers applicable import duties and taxes under DDP service where required.
4. Inventory, Pre-orders & Split Shipments
- Inventory Status: Please check the product page for real-time stock information. If an item is out of stock in our local warehouses, it may be marked as “Pre-order”.
- Pre-order Fulfillment: Pre-order items may be shipped directly from Shenzhen or restocked to a local warehouse first before final delivery.
- Split Shipments: If your order contains both in-stock and pre-order items, we may ship them separately. No additional shipping fee will be charged for split shipments caused by our fulfillment arrangement.
5. Customs, Taxes & Delivery Issues
5.1 Customs and Taxes
For EU Member States:
Whether shipped from Germany or China, OpenELAB covers applicable import duties and taxes under DDP service where required. Customers in EU member states should not be charged additional import duties or VAT upon delivery.
For destinations outside the European Union, such as Switzerland, Norway, and the United Kingdom, import duties, taxes, and customs fees may be charged by local authorities upon delivery. These fees are the responsibility of the recipient.
5.2 Damaged, Delayed, or Lost Parcels
Please inspect your parcel upon delivery where possible. If you notice visible damage, please report it to the courier and contact us as soon as possible. This does not affect your statutory consumer rights.
If your parcel is delayed, lost, returned to sender, or the tracking information has not updated for an unusual period of time, please contact us at info@upenelab.com. We will assist you in checking the shipment status with the courier.
5.3 Incorrect Address or Failed Delivery
If a parcel cannot be delivered due to an incorrect or incomplete address provided by the customer, refusal of delivery, or failure to collect the parcel, additional shipping or return costs may apply.
6. VAT
For orders within the EU, VAT is collected at checkout according to the applicable destination rules. No additional VAT should be collected upon delivery for EU member state orders covered under our DDP shipping arrangement.





