Smart IoT Sensor built with XIAO ESP32C6

Wi-Fi, MQTT, BME280/BME680/SGP41 Integration & Power Management

Table of Contents

• Introduction
• Features
• Usage
• Schematics
• Configuration
• Enclosure
• Integration with Home Assistant
• Getting Started
• Hardware
• Software
• ZigBee
• Contributing
• License
• TODO

Introduction

The Smart IoT Sensor is a power-efficient device built using the XIAO ESP32C6 tiny board. It integrates Wi-Fi connectivity, MQTT messaging, environmental sensing with BME280/BME680 sensors, and robust power management, making it an ideal solution for smart home and IoT applications.

Features

• Wi-Fi Connectivity: Seamless connection to your home or office network.
• MQTT Integration: Publishes sensor data to an MQTT broker in JSON format.
• Environmental Sensing: Supports Bosch BME280 and BME680 sensors for temperature, humidity, and pressure measurements. Supports Sensirion SGP41 VOC and NOx sensor.
• Power Management: Efficiently manages power using LiPo batteries with built-in charge management.
• Deep Sleep Mode: Extends battery life by enabling deep sleep between data transmissions.
• ZigBee Connectivity: Seamless integration with ZigBee networks. Supports standard ZigBee clusters, easily pair your sensor with ZigBee coordinators like Home Assistant.
• Optional Features:
  • Battery voltage monitoring
  • Connection duration tracking
  • Future support for Wi-Fi 6 and Bluetooth provisioning (TODO)

Usage

The Smart IoT Sensor can be easily integrated with Home Assistant for real-time monitoring and automation.

MQTT Data Structure

The sensor publishes data to an MQTT broker in the following JSON format:

{
  "ID": "7i29r9k9ltaxmbev",
  "RSSI": -54,
  "battery_voltage": 4.13,
  "temperature": "24.28",
  "humidity": "29.32",
  "pressure": "999.54",
  "connection_duration_ms": 1672
}

• ID: Unique identifier of the sensor
• RSSI: Wi-Fi signal strength in dBm
• battery_voltage: Current battery voltage
• temperature: Temperature reading from the BME sensor
• humidity: Humidity reading from the BME sensor
• pressure: Pressure reading from the BME sensor
• connection_duration_ms: Time taken to establish the MQTT connection

Schematics

Battery Connection

A battery connection schematic.

Voltage Divider

Voltage divider schematic (if battery voltage monitoring is required).

Note: This solution continuously consumes some current from the battery but is functional for voltage monitoring.

BME280/BME680 Connection

SGP41 Connection

Configuration

This build was developed and tested with ESP-IDF v5.3.1 Follow this instruction to install it. It is required.

Configure the sensor using the following steps:

idf.py menuconfig

Then go to XIAO Sensor Configuration

1. Wi-Fi Configuration: Set up your Wi-Fi credentials to enable network connectivity.

2. MQTT Configuration: Connect the sensor to your MQTT server by providing the necessary broker details.

3. Battery Check (Optional): Enable battery voltage monitoring if power management insights are needed.

4. BME Sensor Configuration (Optional): Choose between BME280, BME680 and SGP41 sensors based on your requirements.

5. Power Management Configuration: Set up wakeup duration, which is the duration in seconds that the device will remain in deep sleep before waking up.

6. 

Enclosure

The sensor is housed in a customizable 3D-printed enclosure. STL files are available for download and 3D printing. To customize a model use a FreeCAD project. A 3D preview is available here.

When printing, it is recommended to orient the parts on the hotbed as shown in the picture:

Enclosure assembly steps:

1. Insert XIAO board into SoC_holder :

2. Insert holder into the core part :

Pull down until it can't go any farther

3. Insert SoC bracket :

4. Insert BME sensor

5. Attach an antenna. Put the coaxial wire into the channels in the core part. Use a couple of drops of glue or double-sided tape to secure the antenna in its place.

6. Now solder up everything together according to schematics. And repeat an assembly steps if everything fits nicely.

7. Insert lock into the core part as shown:

8. Finally, pull the wrapper onto the core part. Ensure that the lock is securing the wrapper.

Integration with Home Assistant

Integrate the Smart IoT Sensor with Home Assistant by following these steps:

1. Set Up MQTT Server: If you don't have an MQTT server, refer to the Home Assistant MQTT Integration guide.
2. Configure configuration.yaml: Add the following configuration to your configuration.yaml file to define the sensor entities.

---
mqtt:
  sensor:
    - name: "Sensor RSSI 7i29r9k9ltaxmbev"
      device_class: signal_strength
      state_topic: "xiao/sensor/7i29r9k9ltaxmbev/data"
      unit_of_measurement: "dBm"
      value_template: "{{ value_json.RSSI }}"

    - name: "Sensor Temperature 7i29r9k9ltaxmbev"
      device_class: temperature
      state_topic: "xiao/sensor/7i29r9k9ltaxmbev/data"
      unit_of_measurement: "°C"
      value_template: "{{ value_json.temperature }}"

    - name: "Sensor Humidity 7i29r9k9ltaxmbev"
      device_class: humidity
      state_topic: "xiao/sensor/7i29r9k9ltaxmbev/data"
      unit_of_measurement: "%"
      value_template: "{{ value_json.humidity }}"

    - name: "Sensor Pressure 7i29r9k9ltaxmbev"
      device_class: pressure
      state_topic: "xiao/sensor/7i29r9k9ltaxmbev/data"
      unit_of_measurement: "hPa"
      value_template: "{{ value_json.pressure }}"

    - name: "Sensor Battery Voltage 7i29r9k9ltaxmbev"
      device_class: voltage
      state_topic: "xiao/sensor/7i29r9k9ltaxmbev/data"
      unit_of_measurement: "V"
      value_template: "{{ value_json.battery_voltage }}"

    - name: "Sensor Connection Duration 7i29r9k9ltaxmbev"
      device_class: duration
      state_topic: "xiao/sensor/7i29r9k9ltaxmbev/data"
      unit_of_measurement: "ms"
      value_template: "{{ value_json.connection_duration_ms }}"

3. Restart Home Assistant: After updating the configuration, restart Home Assistant to apply the changes.
4. Configure Entity Card: Here is an example configuration for the entity card:

---
type: entities
entities:
  - entity: sensor.sensor_temperature_7i29r9k9ltaxmbev
    icon: mdi:thermometer-low
    secondary_info: last-changed
    name: Temperature
  - entity: sensor.sensor_humidity_7i29r9k9ltaxmbev
    name: Humidity
  - entity: sensor.sensor_pressure_7i29r9k9ltaxmbev
    name: Pressure
  - entity: sensor.sensor_rssi_7i29r9k9ltaxmbev
    icon: mdi:wifi-strength-3
    secondary_info: none
    name: RSSI
  - entity: sensor.sensor_battery_voltage_7i29r9k9ltaxmbev
    icon: mdi:battery-80
    secondary_info: none
    name: Battery
  - entity: sensor.sensor_connection_duration_7i29r9k9ltaxmbev
    name: Connection Duration
title: Sensor 7i29r9k9ltaxmbev

Getting Started

Follow these steps to set up your Smart IoT Sensor:

1. Clone the Repository

   git clone https://github.com/BegoonLab/xiao-esp32c6-wifi-sensor
   cd xiao-esp32c6-wifi-sensor
   git submodule update --init --recursive

2. Install Dependencies

   Ensure you have the necessary tools and libraries installed. Refer to the Software section for more details.

3. Configure the Sensor

   Edit the configuration files to set your Wi-Fi and MQTT credentials.

4. Build and Flash

   Compile the firmware and flash it to your XIAO ESP32C6 board.

5. Assemble the Hardware

   Connect the BME sensor and battery as per the schematics. 3D print the enclosure and assemble the components.

6. Deploy and Monitor

   Power on the sensor and monitor the data through your MQTT broker and Home Assistant.

Hardware

Components Required

• XIAO ESP32C6: The main microcontroller unit.
• Bosch BME280 or BME680 Sensor: For measuring temperature, humidity, and pressure.
• LiPo Battery: Any standard LiPo battery compatible with XIAO's charge management.
• Voltage Divider Components: If battery voltage monitoring is required.
• Additional Components:
  • Connectors and cables
  • External antenna (optional, but highly recommended for weak Wi-Fi signals). This is RSSI without and then with external antenna:
    • These antennas tested and worked quite well with this build:
    • PCB Antenna 5dBi and U.FL connector
    • 
    • RadioMaster FPV Drone antenna
    • 

Assembly Instructions

1. Mount the Sensor: Connect the BME280/BME680 to the XIAO ESP32C6.
2. Connect the Battery: Ensure the battery is properly connected to the charge management circuitry.
3. Set Up Voltage Divider: If monitoring battery voltage, assemble the voltage divider as per the schematic.
4. Enclose the Assembly: Use the 3D-printed enclosure to house all components securely.

Software

Dependencies

• ESP-IDF: Official development framework for Espressif chips.

Building the Firmware

1. Install ESP-IDF

   Follow the ESP-IDF Getting Started Guide to set up the development environment.

2. Configure the Project

   idf.py menuconfig

   • Set Wi-Fi credentials
   • Configure MQTT broker details
   • Enable or disable optional features

3. Build and Flash

   idf.py build
   idf.py -p <TARGET_PORT> flash

When a sensor misbehaves, it's helpful to output logs to diagnose the issue. By default, logging is disabled. To enable it, follow these steps:

1. Open the configuration menu:

   idf.py menuconfig

2. Navigate to: Component config → Log output → Default log verbosity.
3. Set the verbosity level to Info.
4. Save the changes, and then execute the following command to build, flash, and monitor:

   idf.py -p <TARGET_PORT> build flash monitor

ZigBee

ZigBee can be activated in the menu:

idf.py menuconfig

Navigate to XIAO Sensor Configuration → Select Sensor Connection Type → ZigBee.

Next, go to Component config → Zigbee → Zigbee Enable and set it to ON. Then, go to XIAO Sensor Configuration → ZigBee Configuration and set a Sensor ID.

Build and flash the firmware. After that, the sensor will be ready and will begin commissioning.

To add the sensor to Home Assistant: go to Settings → Devices & Services → Devices → Add Device → Add Zigbee device. Once completed, your sensor will appear on the Devices page:

Note: The SGP41 sensor is not currently supported because the ZigBee protocol does not include VOC and NOx clusters in its specification.

Contributing

Contributions are welcome! Please follow these steps:

1. Fork the Repository

2. Create a Feature Branch

   git checkout -b feature/YourFeature

3. Commit Your Changes

4. Push to the Branch

   git push origin feature/YourFeature

5. Open a Pull Request

License

This project is licensed under the MIT License. All rights reserved.

TODO

• Wi-Fi 6 Support: Enhance connectivity options with Wi-Fi 6.
• Bluetooth Provisioning: Implement Bluetooth-based provisioning for easier setup.
• Additional Sensor Support: Expand compatibility with other types of sensors.