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You can build a wireless UV-intensity monitor with a DFRobot Beetle ESP32-C6, a Grove Sunlight Intensity Sensor, and a second ESP32 receiver. The sensor reads light; the Beetle samples it and sends readings directly to the receiver over ESP-NOW, without a Wi-Fi router. The documented project demonstrates readings over serial, but it does not establish calibrated UV-index values or certified measurement accuracy.
What the project does
CETECH’s Maker Pro project, published August 31, 2024, uses a Beetle ESP32-C6 as the transmitting device and a Grove Sunlight Intensity Sensor as its measurement front end. The sensor detects ultraviolet, visible, and infrared light. A second device receives the wireless messages; the tutorial demonstrates transmitter and receiver responses in the serial monitor.
The Beetle handles sensor sampling, code execution, and wireless transfer. ESP-NOW provides direct device-to-device messaging in this design, so a router is not required. The project is a practical way to transmit sensor readings, not a validated UV meter.
Parts and software you need
Hardware
- DFRobot Beetle ESP32-C6 board (also identified in DFRobot’s manual as “DFRobot FireBeetle 2 ESP32-C6”).
- Grove Sunlight Intensity Sensor, based on the Si1151.
- A second compatible ESP32 device to act as the receiver.
- Grove Base Shield, if you want to use its Grove connectors, and suitable jumper wires.
- USB Type-C cable for programming and power.
- A battery or USB power bank for portable use. A battery-powered build also needs an appropriate enclosure for its intended environment.
- Display hardware, if you want local visualization; use the display setup shown in the project tutorial.
Software
- Arduino IDE and the ESP32 board package.
- The Grove_Sunlight_Sensor library.
- WiFi and ESP-NOW support for the transmitter and receiver sketches.
Wire the sensor and prepare the board
- Connect the Grove Sunlight Intensity Sensor to an I2C port on the Beetle ESP32-C6. Use the Grove Base Shield if it suits your wiring setup; otherwise, make the appropriate I2C connections with jumper wires.
- If you want a local display, connect the display hardware as shown in the project tutorial. The wireless link itself does not require a display.
- Connect the Beetle to your computer with USB Type-C. For a portable installation, power it using a battery or USB power bank.
- In Arduino IDE, install the ESP32 board package, select “Beetle ESP32 C6,” and choose the serial port for the connected board. DFRobot’s manual refers to the board selection as “DFRobot FireBeetle 2 ESP32-C6.”
- Install the Grove_Sunlight_Sensor library and make sure the WiFi and ESP-NOW support used by the sketches is available in your ESP32 setup.
Set up ESP-NOW transmission
The transmitter and receiver must agree on the message format and on how each side handles the data. The documented project’s implementation follows this sequence:
#1 Best Overall
- Equipped with high-performance ESP32-C6 32-bit RISC-V processor, up to 160MHz main frequency. Supports Wi-Fi 6, Bluetooth 5 and IEEE 802.15.4 (Zigbee 3.0 and Thread) wireless communication, with superior RF performance, onboard antenna. Built-in 512KB HP Static RAM, 16KB LP Static RAM, 320KB ROM, and external 16MB Flash memory.
- Onboard 2.16inch AMOLED capacitive touch display for clear color picture display, 480 × 480 resolution, 16.7M color. Built-in CO5300 display driver and CST9220 capacitive touch chip, using QSPI and I2C communication respectively, effectively saving the IO resources.
- Support AI voice interaction -- Dual microphones array design, supports more advanced speech interaction functions. Supports intelligent voice dialogue solutions such as Xiaozhi AI and DeepSeek, enabling rapid development of AI voice assistants, smart speakers, and conversational robot prototypes.
- Rich interfaces -- Onboard QMI8658 6-axis IMU (3-axis accelerometer and 3-axis gyroscope) for detecting motion gesture, counting steps, etc. Onboard KEY and BOOT programmable buttons for easy custom function development. Type-C port, improving device compatibility, easier to use. Adapting 1 × I2C, 1 × UART and 1 × USB pads for external devices connection and debugging.
- Power management and scalability -- Onboard PCF85063 RTC chip, powered by Lithium Batt through AXP2101 chip for uninterrupted power supply. Adopts AXP2101 IC for efficient power management, supports multiple voltage outputs, Batt charging, Batt management, and Batt life optimization, etc.
- Initialize the Si1151 sensor and confirm that the transmitter can read it.
- Initialize ESP-NOW on the transmitter and receiver.
- Register a send-status callback on the transmitter to report the outcome of a send attempt.
- Add the receiver as an ESP-NOW peer using its MAC address.
- Use matching message structures on both devices so the receiver interprets the transmitted fields correctly.
- Upload the transmitter sketch to the Beetle and the receiver sketch to the second board. Open each board’s serial output to check the responses demonstrated by the tutorial.
ESP-NOW is a transport for device-to-device messages, not a UV conversion method. The tutorial’s successful serial responses show that the example communicates; they do not prove the sensor has been calibrated or that readings correspond to a standardized UV index.
Understand what the readings mean
The Grove sensor detects UV, visible, and infrared light, but the published project does not provide a calibrated conversion from its output to UV index or irradiance. It also does not state a spectral calibration curve, measurement range, uncertainty, or accuracy. Treat the output as sensor readings for experimentation or relative monitoring, not as a certified measurement of exposure or a substitute for a recognized UV instrument.
Rank #2
- ESP32-C6 is a Micro-controller development board with small size and various digital interfaces
- ESP32-C6FH4 chip is adopted, which is equipped with RISC-V 32-bit single-core processor
- ESP32-C6 Development Board Supports clock frequency up to 160 MHz, and has built-in 320KB ROM, 512KB HP and 16KB LP
- ESP32-C6 Development Board Compatible to expand a variety of peripheral devices, making it more convenient to use.
- In terms of software, you can choose ESP-IDF development environment or for Arduino IED for development
For a meaningful quantitative UV monitor, the key missing step is validation against an appropriate reference across the conditions and wavelengths you intend to measure. Do not infer UV-index units from a raw sensor value or label a display with a standardized unit unless you have established and documented a valid calibration.
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Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallChoose a power and display approach
For bench setup, USB Type-C is the straightforward way to program and power the Beetle. A battery or USB power bank enables a portable build, while an optional display can show readings at the sensor location. A remote receiver can instead present the received data elsewhere.
Rank #3
- ESP32-C6-DevKitC-1 development board using the universal module ESP32-C6--1 with 4 MB SPIflash
- ESP32-C6 development board has complete Wi-F, low-power Bluetooth and other functions
- ESP32-C6--1 uses an onboard PCB antenna, and the module has a built-in ESP32-C6 chip, which has good functionality
- The ESP32 USB Type-C interface of the ESP32-C6 chip supports USB 2.0 full-speed mode and can also be used as the power supply interface of the development board. It can burn firmware to the chip, communicate with the chip through the USB protocol, and can also be used for debugging
- ESP32-C6-DevKit most of the pins of the module on the board have been led out to pin headers on both sides. Developers can easily connect various peripheral devices through jumpers according to actual needs. The development board can also be plugged into a breadboard for use
Espressif’s 2026 ESP32-C6 Series Datasheet v1.5 specifies a 160 MHz maximum high-performance RISC-V clock and 7 µA deep-sleep current for the chip. These are platform specifications, not a runtime estimate for this monitor: actual battery life depends on the board, sensor, radio activity, sleep strategy, power source, and enclosure. The project does not publish runtime testing. Outdoor deployment also requires an enclosure and weather protection appropriate to the installation; the project does not specify a weather-resistant enclosure.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Know the ESP32-C6 platform’s wireless options
The ESP32-C6 supports compatible 2.4 GHz Wi-Fi modes with a data rate of up to 150 Mbps, as well as Bluetooth LE 5.3 and IEEE 802.15.4 features including Thread 1.3 and Zigbee 3.0, according to Espressif’s 2026 datasheet. Those chip capabilities do not mean the project uses all of those protocols: its documented device-to-device implementation uses ESP-NOW. Choose a different transport only if your system needs a distinct connection model, such as a network-based dashboard or another supported radio ecosystem.
Quick Recap
Rank #4
- ESP32-C6-DevKitC-1 development board using the universal module ESP32-C6--1 with 16 MB SPIflash
- ESP32-C6 development board has complete Wi-F, low-power Bluetooth and other functions
- ESP32-C6--1 uses an onboard PCB antenna, and the module has a built-in ESP32-C6 chip, which has good functionality
- The ESP32 USB Type-C interface of the ESP32-C6 chip supports USB 2.0 full-speed mode and can also be used as the power supply interface of the development board. It can burn firmware to the chip, communicate with the chip through the USB protocol, and can also be used for debugging
- ESP32-C6-DevKit most of the pins of the module on the board have been led out to pin headers on both sides. Developers can easily connect various peripheral devices through jumpers according to actual needs. The development board can also be plugged into a breadboard for use
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