The ESPHome powered multisensor

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Embarking on your ESPHome adventure? Kickstart your journey by assembling your own multisensor. It's simpler than you think. Affordable sensors, straightforward wiring, and a foray into custom firmware creation for ESP8266, ESP32, or RP2040 devices await. And if the prospect feels akin to deciphering an alien language, fear not—ample resources, including WhoTheHeck's project, are at your disposal to guide you through.

The ESPHome multisensor mounted to a wall. The device has a micro USB cable plugged in at the bottom.


The Versatile Capabilities of the ESPHome Multisensor

ESPHome multisensors stand out for their ability to monitor a wide range of environmental factors. Typically, enthusiasts monitor temperature, humidity, air quality, and light levels—core components of any smart home setup. Yet, ESPHome supports a vast array of sensors capable of detecting phenomena like incoming thunderstorms, gestures, and even magnetic field strength.

The spotlighted ESPHome multisensor is a versatile device, tracking temperature, humidity, air quality, brightness, and motion. It even features an RGB LED that indicates air quality upon detecting movement. Designed for expandability, this project allows for the integration of additional sensors via 3-pin JST connectors.

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Essential Components

This project utilizes widely available and cost-effective sensors, ensuring accessibility for enthusiasts on a budget. It is tailored for a standard 70×50 mm prototype PCB, though custom PCB files are provided for those preferring a more polished approach, simplifying the soldering process.

At its core, the project employs an ESP8266, with the option to upgrade to an ESP32 for additional features like Bluetooth tracking. However, the ESP8266 suffices for most needs, making it a practical choice for budget-conscious builders.

SHT31: Precision in Temperature and Humidity Measurement

The Sensirion SHT31 is a high-accuracy temperature and humidity sensor renowned for its exceptional precision and reliability. It stands out with its ±2% relative humidity and ±0.3 °C temperature accuracy, making it a preferred choice for applications requiring precise environmental monitoring.

Despite its absence from my recommended sensor list, it operates over a wide voltage range (2.4V-5.5V), making it versatile for integration with various microcontrollers, including the popular ESP8266 and ESP32. Thanks to its factory calibration and digital output, the SHT31 is straightforward to use, eliminating the need for complex calibration by the end-user.

CCS811: Air Quality Monitoring

The ams-OSRAM CCS811 sensor is adept at monitoring VOC and eCO2 levels, essential for indoor air quality assessments. It necessitates a calibration process for accurate results, representing a slightly more complex setup compared to other sensors in the project.

High levels of VOCs and CO2 can lead to various health issues, including respiratory problems and reduced cognitive function, emphasizing the importance of maintaining good indoor air quality.

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BH1750: Ambient Light Sensing

The BH1750 ambient light sensor provides precise lux measurements, enabling intelligent lighting decisions based on room brightness. Its compact design and compatibility with a range of voltages makes it an ideal choice for this ESPHome project.

AM312: Sensing Motion with a Caveat

The AM312, an economical passive infrared (PIR) sensor, excels in motion detection for its price range. Configured as a binary_sensor within ESPHome, it toggles its state to on upon movement detection and reverts to off when no motion is present. Despite its affordability and compact size, the AM312 is susceptible to generating false positives, often attributed to power fluctuations and electromagnetic interference. To mitigate these issues, some users recommend placing the AM312 away from the ESP8266 or ESP32's radio module and integrating a large capacitor near its VCC pin to stabilize its operation. Another suggested workaround involves insulating the sensor board and then applying aluminium tape as a shield. However, the effectiveness of these fixes can vary.

WS2812B: RGB LED Indication

The WS2812B, an individually addressable RGB LED, serves as a visual indicator for air quality, changing colours based on readings from the CCS811 sensor. While not the top choice for functional lighting, its cost-effectiveness and specific use as an indicator make it a suitable addition to the project.

Assembling the ESPHome Multisensor: Precision and Patience

The assembly of the ESPHome multisensor is a rewarding process that requires attention to detail. Starting with the 3D-printed enclosure, the project's design caters to both aesthetic appeal and functional purpose. The enclosure files (back and front), generously shared by the project's creator, allow for customization and adaptation to specific needs. Local 3D printing services can offer assistance if personal resources are limited. Incorporating Fresnel lenses into the design enhances the sensor's functionality, focusing light onto the BH1750 sensor and diffusing the RGB LED's brightness for optimal visibility.

Soldering the components onto the custom or prototype PCB is a crucial step. For those new to soldering, the task might seem daunting, but it is quite approachable with the right tools and some practice. Online tutorials can provide guidance, and the custom PCB design, if chosen, simplifies this step by clearly marking connection points and reducing the likelihood of errors.

Close-up photo of an ESPHome multisensor circuit board. The board features a micro USB port, a Wi-Fi module, various chipsets, resistors, and capacitors.
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ESPHome Firmware Customization: The Heart of Functionality

Customizing the firmware using ESPHome is where this project truly becomes personalized. The project's creator offers a YAML configuration as a starting point, but delving into the firmware's customization allows for a more in-depth understanding and greater control over the multisensor's capabilities.

For beginners, the ESPHome documentation is an invaluable resource, detailing sensor configuration, integration techniques, and advanced features like automation and conditionals. By editing the YAML file, users can define sensor behaviour, set thresholds for notifications, and customize the RGB LED's response to different sensor readings.

A unique aspect of firmware customization is the ability to integrate the multisensor seamlessly with Home Assistant, enabling real-time monitoring and automation within a smart home ecosystem. This direct integration can facilitate actions like adjusting the HVAC system based on temperature readings or triggering alerts when air quality drops.

Through careful assembly and thoughtful firmware customization, the ESPHome multisensor project serves as a hands-on introduction to the world of smart home technology. By combining hardware assembly with software programming, enthusiasts can create a highly functional device that enhances the intelligence and responsiveness of any smart home setup.

A portrait photo oif Liam Alexander Colman, the author, creator, and owner of Home Assistant Guide wearing a suit.

About Liam Alexander Colman

is an experienced Home Assistant user who has been utilizing the platform for a variety of projects over an extended period. His journey began with a Raspberry Pi, which quickly grew to three Raspberry Pis and eventually a full-fledged server. Liam's current operating system of choice is Unraid, with Home Assistant comfortably running in a Docker container.
With a deep understanding of the intricacies of Home Assistant, Liam has an impressive setup, consisting of various Zigbee devices, and seamless integrations with existing products such as his Android TV box. For those interested in learning more about Liam's experience with Home Assistant, he shares his insights on how he first started using the platform and his subsequent journey.

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