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Tasmota 4-Relay Home Automation with Alexa Voice Control

Build a 4-channel smart relay controller with physical buttons and Alexa voice control using NodeMCU/ESP32 and Tasmota. Includes PCB Gerber files for a custom board and step-by-step wiring guide.

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Boards:ESP8266ESP32
Firmware:Tasmota
Use Cases:Home AutomationLight ControlRelay ControlVoice ControlAppliance Control
GitHubBlog Post

Tasmota 4-Relay Home Automation with Alexa Voice Control

Build a 4-channel WiFi relay controller that lets you control four household appliances via Alexa voice commands, physical push buttons, and MQTT. This project includes PCB Gerber files for a compact custom build.

Why This Project

  • Voice control — "Alexa, turn on living room light"
  • Physical buttons — still works without WiFi or voice
  • 4 independent channels — control 4 different loads
  • State persistence — remembers relay states after power loss
  • PCB available — Gerber files for a professional build
  • Under $10 total cost

Components Required

Component Purpose Est. Cost
NodeMCU ESP8266 (or ESP32) WiFi controller $3-5
4-channel 5V SPDT relay module Switches mains loads $3
4× momentary push buttons Physical control $0.50
5V 5A power supply Powers relays and ESP $3
Project enclosure Safety $2

Wiring (ESP8266 NodeMCU)

NodeMCU          4-Ch Relay Module
───────          ─────────────────
D1 (GPIO5)   →   IN1 (Relay 1)
D2 (GPIO4)   →   IN2 (Relay 2)
D5 (GPIO14)  →   IN3 (Relay 3)
D6 (GPIO12)  →   IN4 (Relay 4)
5V           →   VCC
GND          →   GND

Buttons:
SD3 (GPIO10) →   Button 1 → GND
D3 (GPIO0)   →   Button 2 → GND
D7 (GPIO13)  →   Button 3 → GND
RX (GPIO3)   →   Button 4 → GND

Tasmota Setup

  1. Flash tasmota.bin to NodeMCU
  2. Configure module:
# Set as Generic module
Module 18

# Configure GPIOs:
# D1=Relay1, D2=Relay2, D5=Relay3, D6=Relay4
# SD3=Switch1, D3=Switch2, D7=Switch3, RX=Switch4

# Enable Alexa emulation (Hue bridge mode)
Emulation 2

# Set switch mode to toggle
SwitchMode1 2
SwitchMode2 2
SwitchMode3 2
SwitchMode4 2

# Retain relay state after power cycle
PowerOnState 3

# Give friendly names for Alexa
FriendlyName1 Living Room Light
FriendlyName2 Kitchen Light
FriendlyName3 Bedroom Fan
FriendlyName4 Hallway Light

Alexa Discovery

After configuration:

  1. Say "Alexa, discover devices"
  2. Four new devices appear in the Alexa app
  3. Control individually: "Alexa, turn on Kitchen Light"
  4. Create Alexa groups for room-based control

ESP32 Version (8 Relays)

For more channels, use an ESP32 with an 8-channel relay module:

# ESP32 GPIO mapping for 8 relays:
GPIO23=Relay1, GPIO22=Relay2, GPIO21=Relay3, GPIO19=Relay4
GPIO18=Relay5, GPIO5=Relay6, GPIO25=Relay7, GPIO26=Relay8

# 8 switches on remaining GPIOs
GPIO13=Switch1...GPIO4=Switch8

Full ESP32 guide: iotcircuithub.com — Tasmota ESP32 Alexa

PCB Design

Custom PCB Gerber files are available for a compact, professional build:

  • Integrates ESP module, relay drivers, and button connectors on one board
  • Order from JLCPCB or PCBWay for ~$2 for 5 boards

Source: iotcircuithub.com — Tasmota NodeMCU Home Automation

Safety Warning

This project switches mains voltage (110-240V AC). All mains wiring must be done by a qualified electrician. Use proper insulation, enclosures, and wire gauges. Never work on mains circuits while energized.

Compatible Boards

  • NodeMCU ESP8266 — 4 relays + 4 buttons
  • ESP32 DevKit — up to 8 relays + 8 buttons
  • Wemos D1 Mini — compact 4-relay build

Resources

Blog Post

Project writeup & details

GitHub Repository

Source code & project files