The Product

The sections below outline the four subsystems used for the MixMasters KitchenAid.

            Power                           Remote          

Communications    Motor Control

Demonstration

Power

On the mixer side, we used a transformerless power supply to power the microcontroller. Transformerless AC power supplies accept wall-outlet AC voltages (here ~120VAC ) input and produce a low voltage DC output (such as 5 volt here for the micro controller). As for the remote control side, the microcontroller was powered using a 9V alkaline rechargeable battery. We used analog-to-digital conversion to check on the battery level and alert the user via a LED when the voltage drops below a certain threshold value.




Power Supply Schematic

Power Supply Schematic


Remote Schematic

Button (left) and Light Schematics

Remote Interface

The remote consists of 6 arcade buttons used to control the speed of the mixer. Additionally, a power switch for saving power and a restart button for syncing are present. The buttons utilize simple pull-up resistor circuits to pull the relevant microcontroller pin high. This turns the associated LED light on as well as sending the appropriate speed signal through the RF system.

Communications

Communication between microcontrollers is performed wirelessly via Radio Frequency devices. These devices (shown left) use basic Amplitude Shift Keying to transmit data from one microcontroller's Universal Synchronous/Asynchronous Receiver/Transmitter (USART) to another microcontroller. Since only seven commands are necessary for communication, the receiver screens received values against that table of values in order to determine which state to set the mixer to for speed control.




RF Devices

RF Devices


Motor Control Prototype

Motor Control Prototype Circuit

Motor Control

Control of the motor is achieved by using the microcontroller to activate an optoisolator, which in turn, drives a TRIAC, causing the motor to receive power. The motor rotates at a set speed determined by the portion of the 120V sine wave it receives from the TRIAC. A separate optoisolator is used with the microcontroller to detect the zero-crossing of the 120V mains source, in order to ensure the TRIAC is used at the appropriate times.

Motor Control
The manufacturer's circuit inside the KitchenAid Mixer
Remote Control
The original prototype for the button functionality
Remote Control
The prototype for layout of the remote control using cardboard
Motor Control
Pressing the green button produces a dim light (or slower speed on a motor)
Motor Control
Pressing the blue button produces a bright light (or faster speed on a motor)