While we had been using dispensers from the Making and Tinkering lab until now, when our purchased water pumps had been delivered, we had to reconfigure the set up of our circuitry with the new water pumps. First, we had to reassemble the water pumps, removing the capacitor and wires attached. We then soldered (for the first time ever!) wires to our pump to connect it to the Arduino Mega board.
We also sketched out a rough boba dispenser as we knew that making a bubble tea machine would be incomplete without the boba pearls. However, we found it difficult to find a machine or even a container that met our specifications to dispense the boba. For our initial plan, we intended to use a cereal dispenser with a servo or stepper motor.
Working on the user interface, we programmed the LCD display to display different drink options when the matrix keypad is pressed. We also decided to try out the Arduino IoT Cloud, which is using virtual buttons to connect to the microcontroller and LCD display to control our liquid pumps. This is done through the use of the Internet, so we realised that we would need to buy the Arduino Giga board instead as Arduino Mega is unable to connect to the Internet.
(Credits: Arduino)
We also found out through experimenting that the different water pumps dispense liquids at a slightly different rate, so calculating the amount of liquid dispensed in a time-based manner will lead to us having an extremely inaccurate final volume of the drink. Hence, we decided that we will calculate the volume of each liquid dispensed using the weight of each liquid. To do so, we decided to purchase a load cell.
When the load cell arrived, we 3D printed a base and the top cell for the load cell such that the cup could be placed on the load cell for it to be weighed. However, we needed to connect the load cell to a HX711 amplifier as the signal produced by the load cell was weak and needed to be amplified to connect to the microcontroller. Our next challenge? Coding for the load cell such that it can weigh the drinks and start and stop dispensing based on the specified weight.