eMix Smart Bar: Ask Alexa for a Drink

As a Christmas present for my dad, I built a bar robot using old 3D printer parts I had around the house. After completing it, I had the idea for upgrading it by connecting it to WiFi and controlling it using our amazon Alexa devices. After long research into the IoT world and WiFi connected microcontrollers, I was able to successfully build a prototype that has all of the intended functionality, including Alexa-Integrated voice controls.

Challenges Faced:

• Figuring out how to interface the NodeMCU microcontroller with Alexa reliably took a lot of research. I did not understand yet how to make an Alexa skill, so I worked around this by using one microcontroller to simulate smart lights. Then Alexa would turn on and off these lights using voice commands, and the controller would execute different blocks of code depending on which light was being turned on. These blocks of code were strings containing gcode commands, which would be sent over a serial connection to another board flashed with 3D printer firmware which would execute the gcode to properly move the motors.

• Properly driving the different components with enough voltage was difficult. The NEMA 17 stepper motors require a much higher voltage than any of the microcontrollers could supply, so I had to power the motors from an external power supply and ensure the power on timing of the circuit was correct for powering the boards and motors in the proper order with the proper voltage and power.