Hello everyone,

Attached is the design and schematic for my first PCB design.

It is a water control system for a hydroponic tower.

The input (on the right) is 12V from a solar panel.

There are two voltage converters that convert the 12V to 5V. One circuit is used for the peripherals, the other for the ESP and the fixed-voltage regulator, which steps the voltage down to 3.3V.

The loads controlled by the relays are each 12V, 18W.

Do you need any further information so you can evaluate this or suggest improvements?

Since, as I mentioned, this is my first design (both schematic and PCB), I’d like to hear your opinion before I order it.

Thanks in advance to all of you for your time and help.

You’ll find a project description attached.

Technical Fact Sheet: HydroPCB

HydroPCB is an control solution for vertical hydroponic systems, specifically engineered for high signal integrity and reliability in EMI-heavy environments (near pumps and motors).

Core Specifications

• MCU: ESP32-WROVER (DevKitC) with integrated WiFi/BLE capabilities.
• Storage: External 32MB NOR-Flash (SPI) for high-resolution, long-term data logging.
• Power Management: MIC29300 LDO voltage regulator (TO-220 package); rated for 3A peak load (stepping 5V down to 3.3V).
• PCB Stackup: 4-layer design featuring a dedicated GND plane (Layer 3) and extensive via stitching for thermal dissipation and EMI shielding.

I/O & Sensing

• I2C Expansion: PCF8575 port expander managing 11 dedicated switch inputs.
• Signal Conditioning: All 11 inputs feature hardware debouncing via RC low-pass filters (10kOhm / 100nF) to ensure EMV immunity.
• Thermal Monitoring: 3x One-Wire bus interfaces (DS18B20) for water and ambient temperature tracking.
• Safety Inputs: Dedicated digital input for a float switch (GPIO 27) and an analog ADC voltage divider for battery voltage monitoring (GPIO 34).

Actuators & Interfaces

• Power Switching: 2x NPN-driven relay outputs for independent water and air pump control.
• User Interface: I2C header for OLED/LCD displays, protected by a USBLC6-2SC6 ESD protection IC.
• Feedback: Transistor-driven acoustic buzzer for alarm signaling.

Control Logic & Firmware Concept

• Hybrid Operation: "OR-gate" logic priority between physical hardware switches and software automation.
• Master Override: A central "Master Automatik" switch allows for a complete decoupling of software logic from the hardware layer for maintenance.
• Growth Phases: Hardcoded scheduling for Seeding, Growth, and Intensive cycles.
• Bypass Functions: Dedicated hardware switches to manually override Thermal and Battery protection routines in case of sensor failure.

Protection Measures

• EMI Mitigation: Continuous ground planes and minimized trace lengths to filter capacitors.
• Thermal Safety: Oversized voltage regulator with high current overhead and heat sink mounting options.
• Bus Stability: 4.7kOhm pull-up resistors on all I2C and One-Wire communication lines for clean signal edges.