automatic cat flap

a cheap arduino cat flap with hot glue.

- arduino nano
- servo motor(the size from RC car steering)
- 2/4x 6mm M3 screws
- SR04 ultrasonic sensor
- 6x 15mm wall mouting screws (not too thick, around 2mm is good)
- thick paperclip (1mm thick)
- whatever method of mounting the hook to the flap

servo to D3
ultrasonic: trig to D8, echo to D9
power the servo with the same power source of the nano (not 5v pin)

boom boom