Autofeeder

Autofeeder Controller

Drop-in PCB replacement for a timed chicken feed dispenser. ESP32-C6 based with Matter/ESPHome, local standalone operation, motor control, CAN bus, RTC timekeeping, and optional GPS sync.

Features

• MCU: ESP32-C6-Zero (Matter, WiFi 6, Thread, BLE 5) — socketed via 2×9 2.54mm headers + 7 pogo pins
• Display: SSD1306 128×64 SPI OLED with full menu system (status, schedules, settings, GPS, manual feed)
• Motor: DRV8871 H-bridge for 4VDC auger motor
• Power: 18650 Li-ion with TP4056 charger + DW01A/FS8205A battery protection + TPS63031 buck-boost to 3.3V
• RTC: DS3231 module (I2C) with CR2032 backup for offline timekeeping
• GPS: NEO-6M/8M module header (UART) for offline RTC time sync
• CAN Bus: SN65HVD230 via USB-C SBU pins
• USB-C: 5V charging + CAN sideband on SBU pins
• Buttons: 6 tactile switches (GP0–GP5) for menu navigation
• Standalone operation: Schedules stored in NVS, RTC keeps time without network, full local control via screen and buttons

Project Structure

hardware/kicad/          — KiCad design files (generated)
  ├── autofeeder.kicad_sch      — Generated schematic
  ├── autofeeder.kicad_pcb      — Generated PCB (autorouted + verified)
  ├── autofeeder.kicad_pro      — KiCad project settings
  ├── sheet_specs/autofeeder.py — Python schematic generator
  └── autofeeder_pcb.py         — Python PCB pipeline (place, route, pour, verify, export)
hardware/symbols/         — Custom KiCad symbol library
hardware/footprints/      — Custom KiCad footprints (ESP32-C6-Zero socket, OLED module)
firmware/esphome/         — ESPHome configuration
docs/                     — BOM, pinout, mechanical specs
fabrication/              — Gerbers, drill, BOM, CPL (for JLCPCB)
tools/sch_gen/            — KiCad S-expression generation library

Pin Assignments

See docs/pinout.md for full GPIO table.

Key assignments:

• GP0–GP5: Buttons (individual GPIOs)
• GPIO19/20: Motor control (TX/RX repurposed)
• GP14/15/18/12: Display SPI (DC on GP12 via pogo pin)
• GP21/22: CAN bus
• GP6: Battery monitor ADC
• GP13/23: I2C for DS3231 RTC
• GP7/8: UART for GPS module

Standalone Operation

The controller runs independently of Home Assistant/ESPHome:

• RTC: DS3231 keeps time with coin cell backup during power loss
• Schedules: Up to 4 daily feeding times stored in ESP32 NVS
• Display: Full menu system — status, manual feed, schedule list, time set, GPS status, settings
• Buttons: POWER (back), TIMER (cycle), MANUAL (feed), SETTINGS (confirm/toggle), UP/DOWN (adjust)
• GPS: Optional module for offline time synchronization
• Matter: When network is available, schedules can also be managed via Home Assistant

Build

Schematic

PYTHONPATH=tools python3 hardware/kicad/sheet_specs/autofeeder.py

PCB

# Requires KiCad 9.0+ and Freerouting on PATH
PYTHONPATH=tools python3 hardware/kicad/autofeeder_pcb.py

Firmware

cd firmware/esphome
esphome run autofeeder.yaml

BOM

See docs/bom.md for full bill of materials.

Required additions (not on main board)

• DS3231 RTC module (ZS-042) with CR2032 cell
• NEO-6M/7M/8M GPS module (optional)
• 7× pogo pins 0.9mm × 11mm (for Zero bottom-edge pads)

License

CERN Open Hardware Licence Version 2 - Weakly Reciprocal (CERN-OHL-W-2.0)