ESP32-C6 Environmental Sensor Station & Data Logger

An open-source, 4-layer IoT environmental monitoring station and telemetry data logger powered by the ESP32-C6-WROOM-1 microcontroller. This board utilizes multi-protocol wireless connectivity (Wi-Fi 6, BLE 5, and Zigbee/Thread) to read atmospheric and gas sensors, display local telemetry, and securely back up data to a local MicroSD card.

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🛠 Core Features & Hardware

1. Processor & Wireless Connectivity

• MCU: ESP32-C6-WROOM-1
• Programming/Debugging: On-board dual-purpose interfaces for flashing and debugging via a protected USB-C 2.0 interface.

2. Comprehensive Sensor Array

• SCD41-D-R2: Photoacoustic $CO_2$ sensor measuring true carbon dioxide levels in ppm ($I^2C$ Address: 0x62).
• SGP41-D-R4: Digital gas sensor providing multi-pixel MOx sensing for VOC (Volatile Organic Compounds) and $NO_x$ (Nitrogen Oxides) indoor environmental indexes ($I^2C$ Address: 0x59).
• HDC2033: Low-power, high-accuracy digital temperature and relative humidity sensor ($I^2C$ Address: 0x44).

3. Storage & User Interface

• MicroSD Card Slot: Dedicated SPI-driven logging interface with individual inline trace damping resistors and pull-ups for secure local data logging.
• OLED Display (SSD1306): 0.96" $I^2C$ graphic display panel for live visual terminal outputs and local troubleshooting ($I^2C$ Address: 0x3C).

4. Power & Battery Management

• Charging: TP4056 lithium battery management IC with automated charge/discharging indicator LEDs.
• Power Path Switching: Automated hardware power routing utilizing an AO3401A P-Channel MOSFET to seamlessly switch between USB power and Battery power.
• Regulator: AP2112K-3.3V Ultra-low dropout, low-noise LDO regulator supplying clean $3.3\text{V}$ power rails up to $600\text{mA}$ to the wireless MCU and sensors.

5. Push Button Switch

• Reset switch A button with ESD protection to reset the MCU
• BOOT switch A BOOT switch button to enter into bootloading mode for new firmware flashing

5. I2C and UART Pin Connector

• External i2c pin header
• External UART pin header

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🎛 4-Layer PCB Stackup Architecture

This board is structured with an optimized 4-layer stackup:

• Layer 1 (Top Copper - F.Cu): High-speed digital signals, data busses ($I^2C$, SPI), and component placement.
• Layer 2 (Internal Plane 1 - In1.Cu): Solid Ground Plane (GND) providing direct, uninterrupted return paths for low EMI noise and optimal RF shielding.
• Layer 3 (Internal Plane 2 - In2.Cu): Split Power Plane ($+5\text{V}$, $+3.3\text{V}$, $\text{VBAT}$) providing low-impedance power distribution directly below signal lines.
• Layer 4 (Bottom Copper - B.Cu): Secondary signal traces and clean copper pours for thermal dissipation.