CatFeeder

Cat Feeder — ESP32-C3 automatic feeder

Automatic dry food dispenser. An ESP32-C3 SuperMini drives a 28BYJ-48 stepper motor through a ULN2003 module, turning a 3D-printed auger screw that dispenses food pellets. Feeding is triggered by a time schedule or by a physical button press. The device runs from a single 18650 cell and sleeps between events.

Hardware

Wiring

See schematic in schema/KiCad/cat_feeder.pdf or open the KiCad project at schema/KiCad/CatFeeder.kicad_sch.

Pin map (ESP32-C3 SuperMini):

Power path: 18650 → TP4056 → ESP32-C3 VIN (always on) and 18650 → TP4056 → AP3602A VIN → 5 V → ULN2003 + motor (switched via GPIO 10).

Software setup

Requirements

• VS Code with the PlatformIO IDE extension
• USB cable (the C3 SuperMini uses native USB — port appears as /dev/ttyACM0 on Linux)

Build and flash

1. Open the CatFeeder/ folder in VS Code (it is the PlatformIO project root).
2. Select the environment:
   • c3 — ESP32-C3 SuperMini (production target)
   • s3 — ESP32-S3 DevKitC-1 (breadboard test; same GPIO numbers)
3. Click Upload in the PlatformIO toolbar, or run:

pio run -e c3 --target upload

4. Open the Serial Monitor at 115200 baud:

pio device monitor -e c3

Flash mode on C3 SuperMini: if the board doesn't enter download mode automatically, hold BOOT (GPIO 9) while pressing RESET, then release RESET.

First-run configuration via Serial console

All configuration is done by typing commands in the PlatformIO Serial Monitor (line ending: \n or \r\n).

1. Configure Wi-Fi for automatic time sync (one-time setup)

The device has no RTC chip. On every cold boot (power-on after battery removed or discharged) it connects to Wi-Fi, fetches UTC time from NTP, then immediately disconnects. Wi-Fi is never used after deep-sleep wakes — only on cold boot.

WIFI_SSID MyNetwork
WIFI_PASS mypassword

Credentials are saved to flash and never need to be entered again. If Wi-Fi is unavailable, the device falls back to manual time entry:

SET_TIME 1750420800

Get the current Unix epoch in your terminal:

date +%s

2. Set the feeding schedule

Times are in UTC. Up to 8 entries, space-separated.

SCHED 07:00 18:30

The schedule is saved to flash (NVS) and survives power-off.

Between scheduled feeds the device is in deep sleep. It wakes automatically at each scheduled time, runs the motor, then sleeps until the next entry.

Scheduled feed limits (config.h):

These limits apply only to the schedule. Button press and FEED serial command are always allowed regardless of how recently the motor ran.

3. Calibrate portion size

Portion size is defined in stepper steps, not time. Calibrate by weighing:

CAL 512       ← run motor 512 steps; weigh the dispensed food
CAL 768       ← try a different value
SAVE          ← commit the chosen step count to flash

Repeat CAL until the dispensed amount matches the desired portion weight. SAVE must be sent explicitly — until then the new value is not persisted.

4. Verify

STATUS        ← show time, steps, portionsToday, schedule with next feed countdown
FEED          ← manual feed (no limits)
RESET_DAY     ← zero portionsToday and lastFeedEpoch (for testing)

All Serial commands

Button behaviour

Power notes

• The device enters deep sleep between feeds. Wake sources: button or RTC timer.
• The 5 V motor rail (boost converter) is switched on only during a dose, then cut.
• Always-on current in deep sleep: ~50–100 µA (ESP32-C3 + LDO quiescent).
• Expected battery life on 3000 mAh 18650 with 4 feeds/day: several months.