Plant esp32-onboard

Plant ESP32 Controller — Monolithic Onboard SMD Edition (Rev 1.0)

This directory contains the production files, Pick & Place centroid files (CPL), Bill of Materials (BOM), KiCad design source files, and 3D renders for the Monolithic Onboard SMD Edition of the Plant ESP32 watering controller.

Rather than mounting an ESP32-C3 SuperMini daughterboard via pin headers, this turnkey edition integrates the official Espressif ESP32-C3-WROOM-02 Wi-Fi + BLE 5 module directly onto the PCB, complete with native USB-C, onboard AMS1117-3.3 power regulation, tactile RESET & BOOT buttons, status/power LEDs, and multi-stage filtering.

Optimized specifically for JLCPCB SMT Assembly using 100% Top-Side placement and prioritizing JLCPCB Basic Parts to keep assembly setup fees to an absolute minimum ($9.00 total for only 3 extended part reels across the entire production run).

3D Previews & Interactive Diagram

Top View (Integrated ESP32-C3 & SMT Components)	Isometric 3D View

Bottom View (Ground Plane & Solder Mask)

👉 Interactive SVG Circuit Diagram & Net Visualizer: circuit_diagram_onboard.html

Architectural Highlights (Rev 1.0)

• Monolithic Single-Board Design:
  • Eliminates daughterboard pin headers, loose sockets, and manual solder alignment issues.
  • Direct solder attachment of the official ESP32-C3-WROOM-02 module with 18 perimeter castellations and a large central thermal ground slug.
• 100% Top-Side SMT Assembly:
  • All surface-mount components reside exclusively on the top (F.Cu / F.Paste) layer.
  • Requires only a single-sided SMT stencil, eliminating double-sided stencil and assembly setup fees.
• Aggressive Feeder Cost Minimization ($9.00 Total Loading Fee):
  • Basic Parts ($0 loading fee): All 0805 passives (resistors, MLCC capacitors), AMS1117-3.3 LDO (SOT-223), AO3400A MOSFET (SOT-23), SS34 Schottky diodes (SMA), and 0805 LEDs are sourced from JLCPCB's permanent Basic Parts library.
  • Extended Parts (Only 3 reels):
    1. ESP32-C3-WROOM-02 (C2934487) — $3.00 feeder fee
    2. USB-C 16-Pin Receptacle TYPE-C-31-M-12 (C165948) — $3.00 feeder fee
    3. TS-1187A SMD Tactile Pushbutton (C318884, shared by SW1 & SW2) — $3.00 feeder fee
• Native USB-C CDC/JTAG Connectivity:
  • Reversible 16-pin USB Type-C receptacle with dual 5.1 kΩ pulldown resistors (R12, R13) on CC1/CC2 for full USB-PD and C-to-C cable compliance.
  • Differential data pair (D+ / D-) routes directly to the ESP32-C3 hardware USB CDC/JTAG peripheral (GPIO 19 and GPIO 18), enabling direct flashing, bootloader entry, and serial monitoring without external USB-to-UART bridge ICs (no CP2102 or CH340 needed).
• Dedicated Dual ADC Voltage Monitoring (Zero Jumpers):
  • 5V Supply Rail Monitor (GPIO 0 / ADC1_CH0): Dedicated 100 kΩ / 100 kΩ divider (R1, R2) + 100 nF filter (C1). Continuously verifies USB/Mains 5V health and detects pump brownouts.
  • 18650 Battery Monitor (GPIO 4 / ADC1_CH4): Dedicated 100 kΩ / 100 kΩ divider (R8, R9) + 100 nF filter (C6). Directly measures raw 18650 Li-ion battery voltage ($3.0\text{V}\text{–}4.2\text{V}$) from TB4 Pin 3 (BAT). Quiescent drain is only 21 µA ($\sim 15\text{ mAh}$ per month), far below the battery's chemical self-discharge!
  • Both channels reside on ADC1, guaranteeing 100% reliable concurrent analog reads during active Wi-Fi streaming.
• Dual Power Input Architecture with Anti-Backfeed Protection:
  • USB-C 5V Input: Powers the board and pump during development, desktop testing, or permanent indoor mains operation.
  • External Solar / Battery 5V Input (TB4-1): Connects to an external solar charge & boost module (e.g. DD05CVSA mini-UPS).
  • Anti-Backfeeding Schottky Diode (D2): 40V 3A SS34 Schottky diode (#C8678) placed in series between TB4-1 (EXT_5V) and the internal +5V rail. Blocks 100% of reverse current from backfeeding into the solar module when USB-C is plugged in.
• Robust Power Regulation & Decoupling:
  • AMS1117-3.3 LDO (U2, SOT-223, Basic Part #C475931): Delivers up to 1000 mA of clean 3.3V logic power with wide copper tab heatsinking.
  • Multi-stage ceramic filtering: 10 µF (C10) + 100 nF (C7) at LDO input; 10 µF (C11) + 100 nF (C8) + 22 µF (C12) at LDO output directly adjacent to the ESP32 3V3 power pin.
• Hardware Pushbuttons & Status Indicators:
  • RESET Button (SW1): Pulls EN to GND. Debounced by a 10 kΩ pull-up (R10) and 1 µF capacitor (C9).
  • BOOT Button (SW2): Pulls GPIO 9 to GND for manual ROM bootloader entry. Pulled high by 10 kΩ (R11).
  • PWR LED (D3, Green): Indicates 3.3V rail health.
  • STAT LED (D4, Blue): Active-low status indicator driven by GPIO 8 via 1 kΩ resistor (R15). Connected to +3.3V to ensure GPIO 8 is pulled HIGH during boot strapping.
• RF Optimization & Antenna Keepout:
  • ESP32-C3-WROOM-02 inverted-F antenna points outward toward the bottom board edge.
  • Full copper keepout (no ground plane, no traces, no vias on top or bottom copper) under the antenna keepout zone.

Bill of Materials (BOM) & LCSC Part Mapping

SMT Assembly Parts (Factory Pre-Soldered by JLCPCB)

Through-Hole Connectors & Hand-Soldered Parts (or DNP)

Production Files

• 📦 Gerber & Drill Package: plant-esp32-onboard_gerbers.zip (Contains Protel RS-274X Gerbers and separate PTH/NPTH drill files)
• 📋 SMT Assembly BOM (JLCPCB): plant-esp32-onboard_bom.csv (100% CPL match with verified LCSC part numbers)
• 📍 Pick & Place Centroid File: plant-esp32-onboard_cpl.csv (Aux origin at bottom-left corner (0.0, 54.0), all coordinates strictly positive)
• 📋 Hand-Solder BOM: plant-esp32-onboard_hand_solder_bom.csv
• 📐 KiCad PCB File: plant-esp32-onboard.kicad_pcb
• 📄 KiCad Schematic: plant-esp32-onboard.kicad_sch
• 🌐 Interactive Circuit Diagram: circuit_diagram_onboard.html
• 🛡️ DRC Verification Report: drc_report_onboard.txt (0 Violations, 0 Unconnected Nets)

Cost Breakdown (Per 10 Boards)

ESP32-C3-WROOM-02 GPIO Pinout Table

Flashing & Firmware Development

Native USB CDC/JTAG

The onboard ESP32-C3-WROOM-02 features a built-in USB Serial/JTAG controller connected directly to the USB-C port (GPIO 18 / GPIO 19). No driver installation is required on modern operating systems (macOS, Windows 10/11, Linux).

PlatformIO Configuration (platformio.ini)

[env:esp32-c3-devkitm-1]
platform = espressif32
board = esp32-c3-devkitm-1
framework = arduino
upload_speed = 921600
monitor_speed = 115200
build_flags = 
    -D ARDUINO_USB_MODE=1
    -D ARDUINO_USB_CDC_ON_BOOT=1

Arduino IDE 2.x Settings

• Board: ESP32C3 Dev Module
• USB CDC On Boot: Enabled
• Upload Mode: USB-OTG CDC (TinyUSB) or Hardware CDC and JTAG
• Port: Select the identified /dev/cu.usbmodem* (macOS) or COM* (Windows) device.

Entering ROM Bootloader Manually (If Required)

Under normal circumstances, the esptool software automatically toggles the ESP32-C3 into download mode via USB CDC control lines. If a bricked firmware prevents auto-reset:

1. Press and hold the BOOT button (SW2).
2. Press and release the RESET button (SW1).
3. Release the BOOT button (SW2).
4. The ESP32-C3 is now in ROM bootloader mode ready for flashing.

Analog Voltage Calculations

// 12-bit ADC with 3.3V full-scale reference (attenuation 11dB)
// GPIO 0: 5V Rail Sense (100k / 100k divider -> ratio = 2.0)
float read5VRail() {
    uint32_t raw = analogReadMilliVolts(0);
    return (raw * 2.0f) / 1000.0f; // Volts
}

// GPIO 4: 18650 Battery Sense (100k / 100k divider -> ratio = 2.0)
float readBatteryVoltage() {
    uint32_t raw = analogReadMilliVolts(4);
    return (raw * 2.0f) / 1000.0f; // Volts (3.0V = 0%, 4.2V = 100%)
}

JLCPCB SMT Ordering Step-by-Step Guide

1. Upload Gerber Package:
   • Go to JLCPCB.com and click Add Gerber file.
   • Upload plant-esp32-onboard_gerbers.zip.
   • Set dimensions: 74.0 mm × 54.0 mm, 2 layers, PCB thickness 1.6 mm, Solder mask Green, Silkscreen White, Surface finish HASL (with lead) or LeadFree HASL.
2. Enable PCB Assembly:
   • Switch the PCB Assembly toggle to ON.
   • Select Assemble top side only (Bottom side: No).
   • Tooling holes: Select Added by JLCPCB.
3. Upload BOM & CPL:
   • Upload plant-esp32-onboard_bom.csv to the Bill of Materials field.
   • Upload plant-esp32-onboard_cpl.csv to the Pick & Place / Centroid field.
4. Review Component Placement:
   • Verify all 0805 components, SOT-223 regulator, SMA diodes, USB-C receptacle, tactile buttons, and ESP32-C3 module align with their silkscreen footprints.
   • Note: The CPL file has been pre-rotated according to EIA-481 tape & reel packaging standards (AO3400A at 90.0°, ESP32-C3 at 180.0°, USB-C at 270.0°).
5. Checkout:
   • Complete payment and receive turnkey, pre-assembled boards!