ESP32-WROOM-32D • Si7021 • Relay • USB • Qwiic • 4-Layer PCB
A custom 4-layer ESP32-based hardware platform integrating environmental sensing, wired connectivity, relay control, USB programming, and expansion interfaces.
Schematic • BOM • Gerbers • KiCad Files
The 4-Layer ESP32 IoT Monitoring and Control Board is a custom embedded hardware platform built around the ESP32-WROOM-32D module.
The board combines environmental sensing through the Si7021-A20, serial and wired interfaces, relay control, USB connectivity, Qwiic expansion, and general-purpose GPIO in a compact 4-layer PCB design.
The complete hardware package is included in this repository, covering the native KiCad project, electrical schematic, PCB layout, BOM, Gerber and drill manufacturing files, pick-and-place data, and PCB documentation.
Status: Design files and manufacturing outputs included.
| Resource | Description |
|---|---|
| Schematic PDF | Complete electrical schematic |
| Bill of Materials | Component BOM |
| Gerber & Drill Files | PCB manufacturing outputs |
| KiCad Project | Native KiCad design files |
| PCB Images | 3D renders and layer views |
| Pick-and-Place Data | Component placement data |
| ERC / DRC Reports | Design verification screenshots |
| Feature | Details |
|---|---|
| Main Controller | ESP32-WROOM-32D |
| Environmental Sensor | Si7021-A20 |
| Sensor Interface | I²C |
| Serial / Expansion | UART / GPIO |
| Relay Control | RT314A05 relay |
| USB | USB 2.0 Type-C interface |
| Expansion | Qwiic connector |
| PCB | 4-layer PCB |
| EDA Software | KiCad |
| Manufacturing Data | Gerber + PTH/NPTH drill files |
| Assembly Data | Top and bottom pick-and-place files |
The design brings together several functional blocks around the ESP32 controller.
The ESP32-WROOM-32D provides the primary processing and wireless connectivity platform for the board.
The Si7021-A20 provides digital environmental sensing through an I²C interface.
A RT314A05 relay provides a dedicated switched-output function with associated transistor drive circuitry.
The board includes a USB Type-C USB 2.0 interface and associated USB interface circuitry.
A Qwiic connector provides an additional I²C expansion interface.
The board is implemented as a 4-layer PCB using KiCad.
- 4-layer PCB architecture
- ESP32-WROOM-32D module
- Environmental sensor interface
- Relay control circuitry
- USB Type-C interface
- Qwiic expansion
- Dedicated internal copper layers
- Compact component placement
- Through-hole and surface-mount components
- PTH and NPTH manufacturing data
The native KiCad project is located in:
| File | Description |
|---|---|
IOT.kicad_pro |
KiCad project |
IOT.kicad_sch |
Schematic source |
IOT.kicad_pcb |
PCB layout |
The exported electrical schematic is available as:
The schematic documents the ESP32 controller, environmental sensor, USB interface, relay control, Qwiic interface, power circuitry, and associated support components.
The current component BOM is available here:
The BOM contains the component references, quantities, values, footprints, and associated component information from the design.
The generated manufacturing package is available under:
The package contains:
- Front copper
- Back copper
- Inner copper layer 1
- Inner copper layer 2
- Front solder mask
- Back solder mask
- Front silkscreen
- Back silkscreen
- Front solder paste
- Back solder paste
- Board outline
- PTH drill data
- NPTH drill data
- Gerber job file
Assembly placement data is available in:
The repository contains separate top-side and bottom-side component placement files.
Design verification artifacts included with the project:
| Item | Status |
|---|---|
| Schematic | ✅ Completed |
| PCB Layout | ✅ Completed |
| PCB Layer Count | ✅ 4-layer |
| KiCad Project | ✅ Included |
| BOM | ✅ Included |
| Gerber Files | ✅ Generated |
| Drill Files | ✅ Generated |
| Pick-and-Place Data | ✅ Included |
| ERC Documentation | ✅ Included |
| DRC Documentation | ✅ Included |
| PCB Documentation | ✅ Included |
.
├── hardware/
│ └── kicad/
│ ├── IOT.kicad_pro
│ ├── IOT.kicad_sch
│ └── IOT.kicad_pcb
│
├── manufacturing/
│ ├── gerbers/
│ │ ├── IOT-F_Cu.gbr
│ │ ├── IOT-In1_Cu.gbr
│ │ ├── IOT-In2_Cu.gbr
│ │ ├── IOT-B_Cu.gbr
│ │ ├── IOT-F_Mask.gbr
│ │ ├── IOT-B_Mask.gbr
│ │ ├── IOT-F_Silkscreen.gbr
│ │ ├── IOT-B_Silkscreen.gbr
│ │ ├── IOT-F_Paste.gbr
│ │ ├── IOT-B_Paste.gbr
│ │ ├── IOT-Edge_Cuts.gbr
│ │ ├── IOT-PTH.drl
│ │ ├── IOT-NPTH.drl
│ │ └── IOT-job.gbrjob
│ │
│ └── pick-and-place/
│ ├── IOT-top.pos
│ └── IOT-bottom.pos
│
├── bom/
│ └── IOT_BOM.csv
│
├── docs/
│ ├── images/
│ │ ├── 3D_front_1.png
│ │ ├── 3D_front_2.png
│ │ ├── 3D_BACK.png
│ │ ├── Layout_front_layer.png
│ │ ├── Layout_inner_layer_1.png
│ │ ├── Layout_inner_layer_2.png
│ │ ├── Layout_Bottom_layer.png
│ │ ├── ERC.png
│ │ └── DRC.png
│ │
│ └── IOT_Schematic.pdf
│
├── .gitignore
├── CONTRIBUTING.md
├── LICENSE
└── README.md
This repository contains the hardware design package for the 4-Layer ESP32 IoT Monitoring and Control Board.
The repository includes the native KiCad source files together with the associated schematic, PCB documentation, BOM, manufacturing outputs, and assembly data.
Contributions, design reviews, and hardware improvements are welcome.
For proposed revisions, keep the native KiCad design files and associated documentation aligned with the corresponding hardware revision.
The hardware design files in this repository are licensed under the CERN Open Hardware Licence Version 2 - Strongly Reciprocal (CERN-OHL-S-2.0).
The CERN-OHL-S-2.0 licence is a hardware-specific open-source licence for sharing, modifying, and distributing covered hardware designs.
Copyright © 2026 Habib Ur Rehman
See LICENSE for the licence information associated with
this repository.
Electronics Engineering
Embedded systems, PCB design, microcontrollers, electronics hardware, and hardware development.
- GitHub: Habib-creater
- LinkedIn: Habib Ur Rehman
4-Layer ESP32 IoT Monitoring and Control Board
Custom ESP32 Embedded Hardware Platform