Offers wireless connectivity, a plethora of pins, and reliability for a low cost.
A low cost was crucial in creating a product that would be comparable to a regular trash can.
GARB requires WiFi in order to send texts to the owner. Additionally, if we were to create an app, we would require Bluetooth connectivity for faster communication.
With the plethora of pins on the ESP32, we could continuously run all the sensors at the same time and add more actuators.
Sensors
Ultrasonic Sensor:
Sensor to determine if the trashcan was full. I did testing to ensure that it would be able to detect different types of trash inside. With an accuracy of 3mm, the HC-SR04 is sufficient for this application.
Push Button (Lid):
Users can depress the button for one second to manually seal up the trash, regardless of fullness. Additionally, it would serve as the reset button after a new bag is loaded.
This is the only physical button that is accessible to the user, ensuring an intuitive interface.
Push Button (Hinge):
If depressed, the ultrasonic sensor would be temporarily deactivated. This is necessary to prevent readings when the lid is open.
Actuators
Continuous Servo:
Create a tight gooseneck at the top of the trash bag to prepare for the sealing.
Servo was chosen because of considerations for DFA: driver motor built-in to save on wiring and be easier to mount. Furthermore, we did not require the higher precision on speed control from a DC Motor.
Power
USB Micro-B Breakout Board:
Provides power to the microcontroller, ultrasonic sensor, and servo. The user would only plug in a USB Micro-B cable.
All of these applications require reliable 5V power. The 5V bus on the ESP32 only can output so much current so it is better to have everything draw power from a breakout board. It was a consideration to use USB-C to power GARB, but it would be an additional cost and we do not require the extra pins that we are afforded by using USB-C.
