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What Actually Broke

A project log for BudKoin: ESP32-Powered Smart Vending Machine

We built a vending machine that doesn't take coins. No quarters, no dollar bills, no jammed change dispensers.

himanshu-dadaHimanshu Dada • 07/14/2026 at 07:18•0 Comments

Week 1: Servo jittered. Ground loop from separate power supplies. Fixed by tying all grounds together.

Week 2: PN532 stopped reading NFC tags. Dead. Replaced with a new one. Added TVS diode on the I2C lines for protection.

Week 3: Product jammed in chute. A bag of chips got stuck. Redesigned chute angle from 30° to 45°. Added a Teflon strip on the slide surface.

Week 4: ESP32 crashed during MQTT publish. Stack overflow in WiFi task. Increased `CONFIG_MAIN_TASK_STACK_SIZE` to 8192 bytes. Stable since.

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