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8. Wearables

Research

My expectations were quite high as this week's assignment was a new topic for me and I had not been able to experiment and delve into this interesting world of electronics until now. Where to start? Liza Stark's lesson was a good and great summary, quite precise with the details that had to be taken into account for the development of the different applications that could be developed. In addition, I reviewed past tutorials that were quite instructive as well to clarify certain terms and important points. At the ESAN fablab, Jorge gave me a general introduction to the language of electronics and an approach to the ARDUINO software, we also practiced with TINKERCAD developing a basic circuit.

References & Inspiration

In the state of the art, the applications are endless... From E-textiles to more advanced wearables, there are several projects where a more functional and practical approach is evident, while others are oriented to a more artistic practice where the intersection between technology and nature is explored, or non-traditional materials creating aesthetic, modern and contemplative pieces that invite reflection and raise scenarios and possible futures. Undoubtedly, everything depends on how the development of the design is conceptualized and the purpose it is given. Here are some examples focused mainly on visual and motion actuators.

Going deeper into the subject, and based on the presentation seen in class, actuators can be classified into three main groups: visual, sound and motion.

Process and workflow

For the first actuators, we started by making a simple circuit to test the operation of a LED by the action of a pushbutton. For this purpose, the following process was followed:

* Microcontroller: XIAO RP2040.
  • Push button: Momentary type (push button).
  • LED light
  • Resistors:
  • A 330Ω resistor to limit the current of the LED.
  • A 10kΩ resistor for the push button pull-down circuit.
  • Cables: For connections.
  • Protoboard: To temporarily assemble the circuit. *Power supply: The microcontroller can be powered via USB.

Circuit design

  1. Connecting the LED

  2. Connect the cathode (short leg) of the LED to GND.

  3. Connect the anode (long leg) to a 330Ω resistor.

  4. Connect the other end of the resistor to a GPIO pin of the XIAO RP2040.

Pushbutton connection

  1. Connect one of the pushbutton terminals to GND.

  2. Connect the other terminal to a 10kΩ resistor and then to 3.3V to implement a pull-down circuit.

  3. Also connect that terminal to the GPIO pin of the microcontroller where the status of the pushbutton will be read

Programming the microcontroller

  1. Install the Arduino IDE: Download and install the software from the official site.

  2. Set up support for XIAO RP2040:

o Tools > Board Manager, install the tools for RP2040 compatible boards.

o Select Seeed XIAO RP2040 as the board in use.

Code Example

#define led D0
#define button D1
void setup() {
  // put your setup code here, to run once:
  pinMode(led, OUTPUT);
  pinMode(button, INPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  int status = digitalRead(button);
  if(status){
    digitalWrite(led, HIGH);
  }
  else{
    digitalWrite(led, LOW);
  }
}

Preparing the LED lights

In order to connect the LED light to the fiber optic it was necessary to adapt it for that purpose. We started by sanding the head of the LED to get a flat and easier to drill it. To do this we used a 1/6” thin milling cutter and with a vise, we adjusted the LED. The first ones didn't come out well as the milling cutter cracked them at some point and they broke. Another important consideration is that the drilling should not touch the internal connection, otherwise the LED would no longer work. Finally, it was possible to obtain an acceptable result where the optical fiber could be inserted.

It was necessary to consider a reinforcement, such as a heat shrinkable, to hold and at the same time cover the area that would be connected to the LED, so that the light could move in a better way along the entire path of the optical fiber. To reinforce the junction, hot silicone is used to join the entrance of the LED light. It is also possible to design and print a case to place, for example, neopixels.

Tests and adjustments

  1. Check physical connections: Make sure that there are no short circuits and that all components are properly connected.

  2. Load the program: Connect the XIAO RP2040 to the computer via USB and load the code.

  3. Test the system: Press the push button and verify that the blue LED lights up.

Final assembly

  • If the circuit works properly, it can be soldered to a board to make it permanent.

  • You could also design and print a protective box to cover the components when you use them in a real project.