Build Instructions

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• 1

  TEST SKETCH 01

  We added a basic blink sketch to the XIAO SAMD21 MCU in order to test this configuration. By passing the sketch via the microcontroller, LED Load turns ON and OFF, indicating that we are ready to continue on to the next stage, which is to add the main sketch to the board.
  

  void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(2, OUTPUT);
  }
  // the loop function runs over and over again forever
  void loop() {
  digitalWrite(2, HIGH);  // turn the LED on (HIGH is the voltage level)
  delay(1000);                      // wait for a second
  digitalWrite(2, LOW);   // turn the LED off by making the voltage LOW
  delay(1000);                      // wait for a second
  }

• 2

  TEST SKETCH 02

  The main sketch was then uploaded into the XIAO SAMD21 configuration.

  By pushing the switch, this code enables the user to toggle between various light brightness levels. An OLED screen, rotated to be viewed in portrait orientation, shows the brightness level currently in use.

  #include <Wire.h>
  #include <Adafruit_SSD1306.h>
  #include <Adafruit_GFX.h>
  #define OLED_WIDTH 128
  #define OLED_HEIGHT 64
  #define OLED_ADDR   0x3C
  const int switchPin = 1;
  const int lightPin = 2;
  int lightMode = 1;
  Adafruit_SSD1306 display(OLED_WIDTH, OLED_HEIGHT);
  void setup()
  {
  pinMode(lightPin, OUTPUT);
  pinMode(switchPin, INPUT_PULLUP);
  digitalWrite(lightPin, LOW);
  display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDR);
  display.clearDisplay();
  }
  void loop()
  {
  if (digitalRead(switchPin) ==LOW)
  {
  lightMode = lightMode + 1;
  if (lightMode == 6)
  {
  lightMode = 1;
  }
  }
  if (lightMode == 1)
  {
  digitalWrite(lightPin, LOW);
  display.clearDisplay();
  display.setRotation(3);
  display.setTextSize(3);
  display.setTextColor(WHITE);
  display.setCursor(5, 55);
  display.println("OFF");
  display.display();
  delay(500);
  }
  else if (lightMode == 2)
  {
  analogWrite(lightPin, 50);
  display.clearDisplay();
  display.setRotation(3);
  display.setTextSize(3);
  display.setTextColor(WHITE);
  display.setCursor(5, 55);
  display.println("20%");
  display.display();
  delay(500);
  }
  else if (lightMode == 3)
  {
  analogWrite(lightPin, 100);
  display.clearDisplay();
  display.setRotation(3);
  display.setTextSize(3);
  display.setTextColor(WHITE);
  display.setCursor(5, 55);
  display.println("40%");
  display.display();
  delay(500);
  }
  else if (lightMode == 4)
  {
  analogWrite(lightPin, 255);
  display.clearDisplay();
  display.setRotation(3);
  display.setTextSize(2);
  display.setTextColor(WHITE);
  display.setCursor(5, 55);
  display.println("100%");
  display.display();
  delay(500);
  }
  else if (lightMode == 5)
  {
  analogWrite(lightPin, LOW);
  display.clearDisplay();
  display.setRotation(3);
  display.setTextSize(3);
  display.setTextColor(WHITE);
  display.setCursor(5, 55);
  display.println("OFF");
  display.display();
  delay(500);
  }
  //delay(200); // see text
  }

  After making sure that the main sketch was working, we started the assembly process.

• 3

  ASSEMBLY PROCESS

  • Using a soldering iron, remove all of the parts from the XIAO expansion board, including the battery, switch, and LED load, to start the assembly process.
  • Next, using a window provided on the expansion board mounting location, we select and position the expansion board on the main body before running all the cables inside.
  • To permanently fasten the expansion board in its position, we utilize four M2 screws.
  • The lithium cell was then installed in the main body.
  • Next, we linked the expansion board to the positive and negative wires of the lithium cell.
  • We turn the ON/OFF switch on the expansion board to confirm that the battery is connected to the board. When we do this, the XIAO SAMD21's status LED illuminates, indicating that the board is receiving power.

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