Electrical

Electrical Schematics

The electrical system of the salad mixer contains 7 subsystem modules that are responsible for different inputs and interactions from the user. All modules are controlled by the PIC32 microcontroller.

PIC32 Microcontroller

PIC32 is the "brain" of the salad mixer. It is responsible for all input and output signal processing and interactions with capacitive switches, servo motor, DC motor, IR sensor, potentiometer, sound board, LED, and display matrix.

Servo Module DC Module

The servo module controls the position of the servo arm, which governs the opening and closing state of the gate. A PWM signal will be sent to servo to rotate it 90 degrees clockwise when capacitor switch is pressed. Similarly, a PWM singal will be sent to servo to rotate 90 degrees counter clockwise when both momentary switches are pressed.

The DC motor controls the ratotation of blade in the mixer. Since the mixer only needs to rotate in one direction, we decided to use a MOSFET to control the motor speed instead of using L298 Motor Drive. By adjusting the gate-source threshold voltage Vgs applied on MOSFET, we can adjust the resistance between drain and source and thus affect the voltage applied on DC motor. A schottky diode is connected in parallel to DC motor to protect MOSFET from high inductance current when motor is suddenly turned off.

IR Sensor & LED Module Soundboard Module

IR sensor is deployed to detect the presense of bowl. As a safety feature, the gate can only be opened when bowl is present. And 4 LED will be turned on when bowl is present.

The Adafruit FX soundboard controls the audio outputs of the salad mixer. We used three different soundtracks for different user user interactions. A phone jack is connected to the soundboard to connect to the headphone.

Display Module

Two MAX7219 LED Matrices are cascaded to create a display for the salad mixer. The display module is connected to PIC32 through a Octal buffer to raise the voltage input to 5V.

Electronics