2 layers65.1 × 35 mm
2 layers25.1 × 25.2 mm
Mini Environmental Sensor
MbFredys/PCB-Mini-Environmental-Sensor14Compact ESP32-C3 environmental-sensor PCB design using BME280 and SGP40 for temperature, humidity, pressure, and VOC-based air-quality sensing.
- Size
- 25.1 × 25.2 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 34
- Nets
- 27
- Pads
- 129
- Tracks, vias
- 347, 15
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 10 Oct 2025
- Updated
- 23 Aug 2026
Overview
Mini Environmental Sensor is an open-source printed circuit board by MbFredys, from the MbFredys/PCB-Mini-Environmental-Sensor repository on GitHub. It is a 2-layer board of 25.1 × 25.2 mm with 34 parts on 27 nets, routed with 347 tracks and 15 vias.
It is built around the ESP32-C3-WROOM-02-H4, BME280 and SGP40-D-R4, with the TPS62203DBV and MCP73831 among its other parts. Its parts include 12 capacitors, 10 resistors, 5 ICs, 2 connectors and 1 diode. It belongs with the sensors and measurement and home automation and IoT boards and the ESP32 and RISC-V boards of this library.
Main components
5
ESP32-C3-WROOM-02-H4
SMD,20x18mm-105dBm -40℃~+105℃ 2.4GHz 20.5dBm 345mA 3V~3.6V 82mA Bluetooth5.0 ESP32-C3 On-board PCB Antenna UART、SPI、I2C、I2S、USB SMD,20x18mm WiFi Modules ROHSEspressif SystemsWiFi Modules
BME280
LGA-8(2.5x2.5)-40℃~+85℃ 0%RH~100%RH 1.71V~3.6V 1.8uA 16bit I2C、SPI ±0.5℃ ±3%RH LGA-8(2.5x2.5) Temperature and Humidity Sensor ROHSBoschTemperature And Humidity Sensor
SGP40-D-R4
DFN-6-EP(2.4x2.4)-10℃~+50℃ 0.85mm 0.8mm 0ppm~1000ppm 1.7V~3.6V 2.44mm 2.44mm 2.6mA Air quality I2C Reset function DFN-6-EP(2.4x2.4) VOC Sensors ROHSSensirionVOC Sensors
TPS62203DBV
SOT-23-5-40℃~+85℃@(TA) 1 15uA 1MHz 2.5V~6V 3.3V 300mA Buck Buck Built-in Fixed Yes SOT-23-5 DC-DC Converters ROHSTexas InstrumentsDC-DC Converters
MCP73831
UncategorisedMicrochip Technology
README
README.mdMini Environmental Sensor
Compact battery-powered environmental-sensing PCB based on an ESP32-C3, BME280, and SGP40.
Project status: Design and manufacturing documentation completed. The PCB has not been fabricated or physically validated.
Project objective
The project explores the integration of environmental sensing, wireless connectivity, battery operation, USB-C charging, and compact PCB layout in a single embedded platform.
Intended measurements
- Temperature
- Relative humidity
- Atmospheric pressure
- VOC-based indoor air-quality signal
The SGP40 is a VOC sensor. This design does not directly measure carbon dioxide.
Hardware architecture
- Controller: ESP32-C3-WROOM-02
- Environmental sensor: BME280
- VOC sensor: SGP40
- Power source: Single-cell Li-ion battery
- Charging: USB-C input with battery-charging circuitry
- Regulation: TPS62203-based power stage
- Interfaces: I²C sensor bus and programming access
Engineering work
- Defined the functional architecture
- Selected the controller, sensors, charging, and regulation components
- Developed the schematic and PCB layout in KiCad
- Considered RF antenna clearance and sensor placement
- Prepared the BOM and manufacturing outputs
Key design considerations
- Sensor exposure to ambient air
- Thermal separation from heat-generating components
- RF antenna keep-out area
- Battery charging and power-path behavior
- I²C routing and pull-up selection
- Sleep-current and power-budget assumptions
Validation still required
A fabricated prototype is required to determine:
- Sensor accuracy and self-heating effects
- Actual sleep current and battery autonomy
- USB-C charging behavior
- Wireless performance
- Thermal behavior
- Enclosure influence on measurements
- EMC/EMI performance
No runtime, cloud dashboard, weather resistance, or battery-life value is claimed until supported by firmware and physical testing.
License
Licensed under CERN-OHL-W-2.0.
Parts
34| Qty | Value | Footprint | References |
|---|---|---|---|
| 4 | 0.1uF | Capacitor_SMD:C_0402_1005Metric | C3, C4, C6, C8 |
| 4 | 10k | Resistor_SMD:R_0603_1608Metric | R1, R2, R3, R4 |
| 4 | 4.7k | Resistor_SMD:R_0603_1608Metric | R7, R8, R9, R10 |
| 4 | 4.7uF | Capacitor_SMD:C_0603_1608Metric | C5, C7, C9, C11 |
| 3 | 1uF | Capacitor_SMD:C_0603_1608Metric | C2, C10, C12 |
| 1 | 10uF | Capacitor_SMD:C_0603_1608Metric | C1 |
| 1 | 10uH | Inductor_SMD:L_0603_1608Metric | L1 |
| 1 | 2k | Resistor_SMD:R_0603_1608Metric | R5 |
| 1 | 470 | Resistor_SMD:R_0402_1005Metric | R6 |
| 1 | BAT_Connector | Connector_Molex:Molex_PicoBlade_53261-0271_1x02-1MP_P1.25mm_Horizontal | J1 |
| 1 | BME280 | Package_LGA:Bosch_LGA-8_2.5x2.5mm_P0.65mm_ClockwisePinNumbering | U3 |
| 1 | ESP32-C3-WROOM-02 | RF_Module:ESP32-C3-WROOM-02 | U1 |
| 1 | LED | LED_SMD:LED_0603_1608Metric | D1 |
| 1 | LOGO | Global_Footprint:InGnia | G*** |
| 1 | MCP73831 | Package_TO_SOT_SMD:SOT-23-5 | U2 |
| 1 | SGP40-D-R4 | Global_Footprint:XCDR_SGP40-D-R4 | U4 |
| 1 | SW_Push | Button_Switch_SMD:SW_Push_SPST_NO_Alps_SKRK | SW1 |
| 1 | TPS62203 | Package_TO_SOT_SMD:SOT-23-5 | U5 |
| 1 | USB_C_PowerOnly | Connector_USB:USB_C_Receptacle_GCT_USB4135-GF-A_6P_TopMnt_Horizontal | J2 |
The 33 most common of 34 parts.
Questions
How big is the Mini Environmental Sensor PCB?
It measures 25.1 × 25.2 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Mini Environmental Sensor use?
34 parts, built around the ESP32-C3-WROOM-02-H4, BME280, SGP40-D-R4 and TPS62203DBV. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the Mini Environmental Sensor KiCad files?
From the MbFredys/PCB-Mini-Environmental-Sensor repository on GitHub, at the commit this page was made from: the board is Kicad Files/Mini_Environmental_Sensor.kicad_pcb and its schematic Kicad Files/Mini_Environmental_Sensor.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Mini Environmental Sensor design in my own project?
Its repository states no licence, so its author keeps all rights: ask MbFredys before reusing the design.
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