M5Stack 4-Relay Unit
Need a larger quantity?
Need bulk pricing?
Get a formal quotation with lead time and volume pricing.
For universities, companies, distributors, and project orders.
M5Stack 4-Relay Unit
Description
Unit 4Relay is a Grove-connected 4-channel relay unit controlled over I2C. Built around the STM32F030F4P6 microcontroller, the Unit 4Relay independently controls four mechanical relays for AC 250V or DC 28V switching, with 10A rated current and 16A maximum instantaneous current.
Each channel on the Unit 4Relay has its own programmable status indicator, and the relay side is physically isolated from the low-voltage control side. With I2C address 0x26, compact 112.0 x 23.0mm form factor, and LEGO-compatible mounting holes, the Unit 4Relay is practical for smart home, industrial control, and digital power switching projects.
Features
- Unit 4Relay provides four independently controlled relay channels.
- Supports AC 250V@10A or DC 28V@10A load switching.
- Each Unit 4Relay channel has a programmable LED status indicator.
- I2C communication over the HY2.0-4P Grove interface at address 0x26.
- Physical isolation between the high-voltage relay side and low-voltage control side.
- Two LEGO-compatible mounting holes for structured installation.
- Compatible with UiFlow1, UiFlow2, Arduino IDE, and Home Assistant workflows.
Specifications
| Specification | Parameter |
|---|---|
| MCU | STM32F030F4P6 |
| Max Input Voltage | AC 250V / DC 28V |
| Rated Current | 10A |
| Max Instantaneous Current | 16A |
| Communication Interface | I2C @0x26 |
| Product Size | 112.0 x 23.0 x 18.0mm |
| Product Weight | 40.0g |
| Package Size | 163.0 x 100.0 x 20.0mm |
| Gross Weight | 84.0g |
Applications
- DC signal switching with Unit 4Relay.
- Power on/off control for digital devices.
- Smart home relay switching.
- Industrial control and power management for high-power equipment.
Product List
- 1 x Unit 4Relay
- 1 x HY2.0-4P Grove connection cable (20cm)
- 4 x VH3.96-4P terminals
Other Content
PinMap
| HY2.0-4P | Black | Red | Yellow | White |
|---|---|---|---|---|
| PORT.A | GND | 5V | SDA | SCL |
I2C Control
The Unit 4Relay uses I2C protocol at address 0x26. The mode control register supports manual LED control or automatic LED sync with relay status, while the relay control register switches LED1-LED4 and RELAY1-RELAY4.
Development
The Unit 4Relay can be developed with UiFlow1, UiFlow2, Arduino IDE, and Home Assistant. These options make Unit 4Relay integration straightforward for controller projects that need four separated relay outputs.
Resources
- 4-Relay Unit product document
- 4-Relay Unit schematics PDF
- 4-Relay Unit model size image
- 4-Relay Unit structure files
- 4-Relay Unit M5Core Arduino example
- 4-Relay Unit UiFlow2 API documentation
- 4-Relay Unit Home Assistant integration
- 4-Relay Unit PDF document
FAQ
How many relay channels does Unit 4Relay provide?
The Unit 4Relay provides four independently controlled relay channels.
What load voltage and current does Unit 4Relay support?
The Unit 4Relay supports AC 250V@10A or DC 28V@10A load switching, with 16A maximum instantaneous current.
What communication interface does Unit 4Relay use?
The Unit 4Relay uses I2C over the HY2.0-4P Grove interface, with I2C address 0x26.
Can Unit 4Relay indicators be programmed?
Yes. Each Unit 4Relay channel has a programmable LED status indicator, and the LEDs can work in manual mode or sync automatically with relay status.
What is included with Unit 4Relay?
The package includes 1 x Unit 4Relay, 1 x HY2.0-4P Grove connection cable (20cm), and 4 x VH3.96-4P terminals.
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.
🚀 Need Faster Shipping?
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.






