# ⚡ Industrial IoT Gateway PCB (ESP32 & STM32)
## 📖 Overview
This repository contains the schematic and PCB layout for an **Industrial-grade IoT Gateway**. The board features a **Dual-MCU chip-down architecture**, integrating bare ESP32 and STM32 microcontrollers directly onto the PCB without relying on pre-assembled modules.
The design is engineered for reliability in industrial environments, featuring a robust power tree, isolated control circuits, and high-speed signal integrity techniques.
## ✨ Hardware Highlights
### 🔋 Power Management (Power Tree)
Designed to accept standard industrial 24V DC input:
* **Step-Down 1 (Buck)**: `LM2596` switching regulator efficiently drops 24V down to 5V.
* **Step-Down 2 (LDO)**: `AMS1117-3.3` linear regulator provides clean, low-noise 3.3V power specifically for the sensitive MCU and sensor logic.
### 🧠 Dual-MCU Chip-down Architecture
* **ESP32**: Handles Wi-Fi/MQTT connectivity and drives the high-speed UI display.
* **STM32**: Dedicated co-processor for real-time sensor polling and hardware execution.
* *Note: Both MCUs are designed as raw SMD components placed directly on the board, heavily reducing the footprint compared to using dev-board modules.*
### 📺 High-Speed SPI Display & Signal Integrity
* Drives a **2.8-inch TFT Display** via the ESP32.
* **Length Matching (Meander Routing)**: The SPI traces (SCK, MOSI, MISO) are carefully routed using meander patterns to achieve exact length matching. This ensures all high-frequency signals arrive simultaneously, eliminating phase shift and data corruption.
### ⚙️ Actuator & Control Circuits
* **Custom Isolated MOSFET Drivers**: Opto-isolated circuitry to safely drive high-current loads without damaging the logic level MCUs.
* **Solid State Relay (SSR) Control**: Zero-crossing/fast-switching control for AC loads.
### 📡 Integrated Sensors
* **INA219**: High-precision I2C current/power monitor to measure the load consumption of the system.
* **Smoke Sensor**: Integrated circuitry for smoke/gas detection.
* **Environmental**: Temperature and Humidity sensor interfaces.
## 📂 Repository Contents
* `/Schematics`: PDF versions of the circuit design.
* `/Gerber`: Manufacturing files ready for JLCPCB/PCBWay.
* `/BOM`: Bill of Materials and Pick & Place files for SMT assembly.
* `/3D_Models`: 3D STEP files of the assembled PCB.
## 📐 PCB Specifications
* **Layers**: 2 or 4 Layers (Specify based on your design)
* **Thickness**: 1.6mm
* **Impedance Control**: Applied on SPI and RF traces.
