Multi-cat households often suffer from food theft when one pet requires a specialized prescription diet. We built and bench-tested an automated feeder driven by an ESP32 microcontroller and an RC522 RFID reader that opens a motorized acrylic hatch only when the authorized microchip badge approaches within three centimeters. During testing on our workbench, we burnt out three breadboard regulators to refine the power delivery network, ensuring high-torque servo spikes never brown out the microcontroller logic.
Wiring the Microcontroller and RFID Module
The primary pinout connects the SPI interface of the RC522 tag reader directly to the designated hardware SPI pins on the ESP32 dev board. Keep cable runs under ten centimeters to prevent signal degradation on the MISO and MOSI lines during high-frequency reads. We placed a 100-microfarad electrolytic capacitor across the logic rail to smooth out sudden current draws during tag handshakes.
Calibrating the PWM Servo Drive
Standard continuous rotation servos require precise pulse-width modulation signals to prevent mechanical binding when driving the acrylic door linkage. Use an external 5V 2A switching supply rather than drawing current directly from the onboard regulator of your development board. Our logic analyzer captures showed significant voltage drop when powering the motor directly from USB supply rails.
Bench-Testing Power Draw and Deep Sleep
To run this system cleanly on battery backup, configure the ESP32 to enter deep sleep between proximity scans. The active circuit consumes roughly 160mA during badge scanning, but drops to under 15 microamps when suspended with interrupt triggers active on the SPI IRQ line. A simple bench multimeter test confirms continuous operation exceeding three weeks on a standard dual 18650 lithium array.