Hydroponics reservoir controller

hydroponics-pcb

KiCad PCB designs for the hydroponics monitoring/control system on a two-tier IKEA growing rack.

Boards

Grow-lamp switching currently stays on the original ESP8266 hydroponics_monitor node and is out of scope for these boards (may move to the reservoir board later).

Tray board peripherals

Display connector (J2, 14-pin) pinout: VCC, GND, CS(D5), RESET(D4), DC(D2), MOSI(D23), SCK(D18), LED(D15), MISO(D34), T_CLK(D18, shared), T_CS(D14), T_DIN(D23, shared), T_DO(D34, shared), T_IRQ(D35). SD card connector (J3, 4-pin, separate from J2): CS(D19), MOSI(D23, shared), MISO(D34, shared), SCK(D18, shared). New GPIOs used: 14, 19, 34, 35 — none of these were previously assigned, so add them to the ESPHome configs without touching the existing pin numbers.

No high-power switching on the tray board. An SP3485EN RS-485 transceiver (120 Ω termination, direction pin on GPIO12) links the two tray boards to the reservoir board.

Comms

All three ESPs talk to Home Assistant over WiFi (ESPHome native API). The tray boards also talk to the reservoir board over RS-485 — a local wired link so fill-level reads and pump control don't depend on WiFi/HA. The reservoir is the controlling node.

Firmware

ESPHome configs live in the separate ha-config repo under esphome/ (hydro-tray-top.yaml, hydro-tray-bottom.yaml). The pin map is shared between the schematic here and those configs — keep them in sync.

Repo layout

tray-board/        KiCad project for the tray sensor board
reservoir-board/   (future) KiCad project for the reservoir board
shared-library/    custom symbol (New_Library) + footprint (Library.pretty)
                   library, referenced by both boards' sym-lib-table/
                   fp-lib-table via ${KIPRJMOD}/../../shared-library/ - keep
                   custom parts (ESP32 DevKit socket, display modules, etc.)
                   here rather than per-board copies, which drift silently
docs/              pin maps, block diagrams, datasheets

Working with KiCad from the CLI

Requires KiCad 10.x (kicad-cli) plus the standard symbol/footprint libraries.

tools/fab.sh tray-board

runs ERC + DRC (fails on any error/warning) and writes a JLCPCB-ready set to tray-board/production/ (git-ignored — regenerated from source): gerbers (Protel extensions) + separate PTH/NPTH Excellon drill files, zipped as <name>-gerbers.zip; <name>-cpl.csv (SMD-only pick-and-place, DNP parts excluded); <name>-bom.csv (DNP excluded, LCSC Part # column from each part's LCSC schematic field). Parts you're sourcing/fitting yourself (e.g. the socketed ESP32 module) should be marked Do Not Populate in the schematic so they're left out of both the BOM and the CPL automatically.

It also runs tools/check_pins.py, which checks the MCU's pin usage for hardware hazards ERC doesn't catch — currently ESP32 strapping pins (GPIO0, 2, 5, 12, 15) with an external pull that conflicts with their required boot-time level, GPIO6-11 (internal flash, must never be used externally), and UART0 (GPIO1/3, reserved for USB-serial). Fails the build on any ERROR-severity finding; can also be run standalone:

tools/check_pins.py path/to/board.kicad_sch