Author: Gherman Maria Irina

RFID Cat Feeder is a “smart” feeder that opens up only when a certain cat wants to eat. It can do this by reading an RFID tag on a cat's collar, or ideally its microchip. The purpose of such a feeder is to stop a gluttonous cat from eating all the food.

The hardware is relatively simple. ESP32 gets info about the RFID tag from an RFID reader. The door motion is controlled by a servo motor. Registering a new tag is done through a button. Two LEDs help the user know what the feeder is currently doing.

To have a safety mechanism so that the door doesn't close on the cat, the feeder uses an ultrasonic sensor to sense if there is a cat in front of it.

• ESP32
• RC522 RFID reader + RFID tag
• HC-SR04 ultrasonic sensor
• 2 x LED (1 green, 1 red)
• Button
• TowerPro SG90 servo motor

#include <ESP32Servo.h> - Easy control of the servo motor, a fork of Arduino's Servo.h that is compatible with ESP32

#include <MFRC522.h> - Library for reading from the RFID reader

#include <SPI.h> - Another library used for the RFID reader

#include <NewPing.h> - A library to simplify the usage of the ultrasonic sensor

The core functionality of the feeder can be simplified in this pseudocode:

loop() {
    if (register mode) {
        turn on red led
    } else {
        turn off red led
    }

    if (button pressed) {
        toggle register mode
    }

    if (reading a card) {
        if (register mode) {
            add card uid to vector
        } else {
            if (card uid is in vector) {
                open door
                wait 5 seconds
                close door if no obstacle
            } else {
                do nothing
            }
        }
    }
}

The full code can be viewed on my github

RC522 example

Servo example

Ultrasonic sensor example