ESP32-S3 Plant Watering System

An automated plant watering system built with ESP32-S3, featuring MQTT communication, OTA updates, and remote monitoring/control capabilities.

Current Project Status

✅ Completed Features

• WiFi Manager: Auto-connect with NVS credential storage
• OTA Updates: Web-based firmware updates via HTTP server
• MQTT Client: Full MQTT integration with NVS credential storage
  • Auto-reconnection
  • Last Will and Testament (LWT)
  • Command subscription
  • Sensor data publishing

🚧 In Progress

• Motor control (TB6612FNG driver)
• Moisture sensor reading
• Automation logic

📋 TODO

• Web dashboard
• Home Assistant integration
• Multiple zone support

Hardware

• MCU: ESP32-S3-MINI-1
• Motor Driver: TB6612FNG (for 2 water pumps)
• Sensors: 2x Capacitive soil moisture sensors
• Power: 12V supply for pumps, 3.3V for logic

Software Architecture

MQTT Topics

Topic	Direction	Description	Example
plant_watering/status	Publish	System online/offline status	"online"
plant_watering/moisture/1	Publish	Moisture sensor 1 reading (%)	"45"
plant_watering/moisture/2	Publish	Moisture sensor 2 reading (%)	"62"
plant_watering/pump/1/set	Subscribe	Pump 1 control command	"on"/"off"
plant_watering/pump/2/set	Subscribe	Pump 2 control command	"on"/"off"
plant_watering/pump/1/state	Publish	Pump 1 current state	"on"/"off"
plant_watering/pump/2/state	Publish	Pump 2 current state	"on"/"off"
plant_watering/config	Subscribe	Configuration updates	JSON config

Configuration

WiFi Settings (menuconfig)

CONFIG_WIFI_SSID="Your_SSID"
CONFIG_WIFI_PASSWORD="Your_Password"

MQTT Settings (menuconfig)

CONFIG_MQTT_BROKER_URL="mqtt://192.168.1.100:1883"
CONFIG_MQTT_USERNAME="plantwater"
CONFIG_MQTT_PASSWORD="your_password"

Plant Watering Settings (menuconfig)

CONFIG_MOISTURE_THRESHOLD_LOW=30    # Start watering below this %
CONFIG_MOISTURE_THRESHOLD_HIGH=70   # Stop watering at this %
CONFIG_WATERING_MAX_DURATION_MS=30000  # Max pump runtime (30s)
CONFIG_WATERING_MIN_INTERVAL_MS=300000 # Min time between watering (5min)

Building and Flashing

Using Docker (Recommended)

Configure the project

docker run --user $(id -u):$(id -g) --rm -v $PWD:/project -w /project -it espressif/idf:latest idf.py menuconfig

Build

docker run --user $(id -u):$(id -g) --rm -v $PWD:/project -w /project -it espressif/idf:latest idf.py build

Flash via USB

docker run --privileged --rm -v $PWD:/project -w /project --device=/dev/ttyACM0 -it espressif/idf:latest idf.py flash -p /dev/ttyACM0

Monitor serial output

docker run --privileged --rm -v $PWD:/project -w /project --device=/dev/ttyACM0 -it espressif/idf:latest idf.py monitor -p /dev/ttyACM0

Flash and monitor in one command

docker run --privileged --rm -v $PWD:/project -w /project --device=/dev/ttyACM0 -it espressif/idf:latest idf.py flash monitor -p /dev/ttyACM0

Note: Replace /dev/ttyACM0 with your actual device port (could be /dev/ttyUSB0, /dev/ttyACM1, etc.)

Using Local ESP-IDF Installation

# Configure the project
idf.py menuconfig

# Build
idf.py build

# Flash via USB
idf.py -p /dev/ttyUSB0 flash monitor

OTA Updates

1. Connect to the same network as the ESP32
2. Navigate to http://<ESP32_IP>/
3. Upload the build/PlantWater.bin file
4. Device will automatically restart with new firmware

Testing with MQTT

Monitor All Topics

# Using Docker
docker run -it --rm --network mqtt-broker_mqtt-network eclipse-mosquitto:2.0.22 \
  mosquitto_sub -h mosquitto -u monitor -P password -t "plant_watering/#" -v

# Using local mosquitto
mosquitto_sub -h 192.168.1.100 -u monitor -P password -t "plant_watering/#" -v

Control Pumps

# Turn Pump 1 ON
docker run -it --rm --network mqtt-broker_mqtt-network eclipse-mosquitto:2.0.22 \
  mosquitto_pub -h mosquitto -u home-server -P password -t "plant_watering/pump/1/set" -m "on"

# Turn Pump 1 OFF
docker run -it --rm --network mqtt-broker_mqtt-network eclipse-mosquitto:2.0.22 \
  mosquitto_pub -h mosquitto -u home-server -P password -t "plant_watering/pump/1/set" -m "off"

# Turn Pump 2 ON
docker run -it --rm --network mqtt-broker_mqtt-network eclipse-mosquitto:2.0.22 \
  mosquitto_pub -h mosquitto -u home-server -P password -t "plant_watering/pump/2/set" -m "on"

# Turn Pump 2 OFF
docker run -it --rm --network mqtt-broker_mqtt-network eclipse-mosquitto:2.0.22 \
  mosquitto_pub -h mosquitto -u home-server -P password -t "plant_watering/pump/2/set" -m "off"

Local mosquitto commands (if installed)

# Subscribe to all topics
mosquitto_sub -h 192.168.1.100 -u monitor -P password -t "plant_watering/#" -v

# Control pumps
mosquitto_pub -h 192.168.1.100 -u home-server -P password -t "plant_watering/pump/1/set" -m "on"
mosquitto_pub -h 192.168.1.100 -u home-server -P password -t "plant_watering/pump/1/set" -m "off"

Current Behavior

When the system is running:

1. On boot: Connects to WiFi, then MQTT broker
2. Status: Publishes "online" to plant_watering/status
3. Sensors: Publishes simulated moisture readings every 10 seconds
4. Commands: Responds to pump on/off commands
5. Feedback: Publishes pump state changes to state topics
6. Disconnect: LWT publishes "offline" to status topic

Project Structure

main/
├── CMakeLists.txt          # Build configuration
├── Kconfig.projbuild       # menuconfig options
├── main.c                  # Main application
├── wifi_manager.c/h        # WiFi connection management
├── ota_server.c/h          # OTA update server
├── plant_mqtt.c/h          # MQTT client implementation
├── led_strip.c/h           # RGB LED control (from template)
├── motor_control.c/h       # (TODO) Pump motor control
└── moisture_sensor.c/h     # (TODO) Sensor reading

Credential Management

Both WiFi and MQTT credentials are stored in NVS (Non-Volatile Storage):

• First boot: Uses menuconfig defaults and saves to NVS
• Subsequent boots: Loads from NVS
• OTA updates: Preserves NVS (credentials survive updates)

To update credentials after deployment:

1. Change in menuconfig
2. Add temporary force-update code
3. Build and OTA update
4. Remove temporary code and update again

Or erase flash completely: idf.py erase-flash

Version History

• v2.0.0-mqtt: Added MQTT client with NVS storage
• v1.0.1: Initial OTA-enabled template
• v1.0.0: Basic LED blink example

Troubleshooting

MQTT Connection Issues

• Check broker is running: docker ps
• Verify credentials match broker configuration
• Ensure ESP32 and broker are on same network
• Check firewall rules for port 1883

WiFi Connection Issues

• Verify SSID has no trailing spaces
• Check password is correct
• Ensure 2.4GHz network (ESP32 doesn't support 5GHz)
• Try erasing flash and reflashing

OTA Update Issues

• Ensure device is connected to network
• Check partition table has OTA partitions
• Verify firmware size fits in OTA partition
• Try accessing http://<ESP32_IP>/test to verify server

Next Development Steps

1. Motor Control Module

   • PWM speed control
   • Safety timeouts
   • Current monitoring

2. Moisture Sensor Module

   • ADC calibration
   • Averaging/filtering
   • Percentage conversion

3. Automation Logic

   • Threshold-based watering
   • Time-based schedules
   • Prevent overwatering

4. Enhanced Features

   • Web dashboard
   • Historical data logging
   • Multi-zone support
   • Weather API integration