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Week 10 - Output Devices ​

Assignments ​

Group Assignment ​

  • Measure the power consumption of an output device

Individual Assignment ​

  • Add an output device to a microcontroller board you've designed, and program it to do something

Group Working ​

My group work is attached here: https://fabacademy.org/2025/labs/unnc/assignments/week9/week09.html

Individual Working ​

This week's assignment involves designing a simple PCB using Fusion 360 to test output devices such as servos and WS2812 LEDs. The PCB will then be processed using the Roland EGX-300

Fusion 360 Design ​

  1. Schematic:

alt text 2. PCB Document:

alt text 3. 3D PCB:

alt text

Manufacturing ​

  1. Import .stl file

alt text 2. Use the model function to rotate the angle by 90° to facilitate subsequent processing.

alt text 3. Choose the type of process finishing

alt text 4. Select cutting surface

alt text 5. Use a 0.5mm milling cutter

alt text 6. Use the default processing area.

alt text 7. Select and create the machining path type contour pitch.

alt text 8. Set the XY speed to 3mm/sec

alt text 9. Generate toolpath

alt text

alt text 10. Connect the computer to the Roland device and start uploading.

alt text 11. Start machining

  1. The picture after completing the machining.

alt text

  • The machined PCB has some issues where the holes and traces are not properly connected, although simulations indicate that these parts should be connected. It is speculated that this may be due to the use of an oversized milling cutter diameter or incorrect parameter settings. To verify and resolve this issue, we plan to attempt machining with a 0.2mm milling cutter.

alt text 13. Picture after soldering completion

alt text

Functional Testing： ​

  1. Use XIAO ESP32 C3 to control WS2812 color change.
  • PIN configuration

alt text

  • PIN function

alt text

  • Add the Adafruit_NeoPixel.h library.

alt text

  • The control code for the WS2812 LEDs is as follows:
cpp
#include <Adafruit_NeoPixel.h>

#define PIN D9            // ESP32-C3 GPIO 0 connected to WS2812 data pin
#define NUM_LEDS 18      // Control 18 WS2812 LEDs

Adafruit_NeoPixel strip(NUM_LEDS, PIN, NEO_GRB + NEO_KHZ800);

void setup() {
  strip.begin();      // Initialize the NeoPixel strip
  strip.show();       // Ensure all LEDs are off at startup
}

void loop() {
  // Set all LEDs to red
  for(int i=0; i<NUM_LEDS; i++) {
    strip.setPixelColor(i, strip.Color(255, 0, 0));  // Red
  }
  strip.show();  // Update LED strip display
  
  delay(1000);  // Delay for 1 second
  
  // Set all LEDs to green
  for(int i=0; i<NUM_LEDS; i++) {
    strip.setPixelColor(i, strip.Color(0, 255, 0));  // Green
  }
  strip.show();  // Update LED strip display
  
  delay(1000);  // Delay for 1 second
  
  // Set all LEDs to blue
  for(int i=0; i<NUM_LEDS; i++) {
    strip.setPixelColor(i, strip.Color(0, 0, 255));  // Blue
  }
  strip.show();  // Update LED strip display
  
  delay(1000);  // Delay for 1 second
}
  1. Use XIAO ESP32 C3 to control servo motor movement.
  • Servo model: SG90

alt text

  • Schematic Diagram

alt text

  • The rotation angle of the servo is achieved by adjusting the duty cycle of the PWM signal. The standard PWM signal has a fixed period of 20ms, with pulse widths typically ranging from 0.5ms to 2.5ms, corresponding to a rotation angle range of 0° to 180°.

alt text

  • When the servo motor moves back and forth between 0° and 180°, the following demonstrates the operational effect.

  • Test Code
cpp
#include <ESP32Servo.h>  // Use the ESP32Servo library

Servo myservo;  // Create a Servo object to control a servo motor

#define SERVO_PIN D10  // Set the pin to control the servo, connected to D10

void setup() {
  myservo.attach(SERVO_PIN);  // Attach the servo to the specified pin
  Serial.begin(115200);  // Initialize serial communication for debugging
}

void loop() {
  // Move the servo from 0 degrees to 180 degrees
  for (int pos = 0; pos <= 180; pos++) {
    myservo.write(pos);  // Move the servo to the specified angle
    delay(15);           // Delay 15 milliseconds to ensure smooth motion
  }

  delay(1000);  // Pause for 1 second

  // Move the servo back from 180 degrees to 0 degrees
  for (int pos = 180; pos >= 0; pos--) {
    myservo.write(pos);  // Move the servo to the specified angle
    delay(15);           // Delay 15 milliseconds to ensure smooth motion
  }

  delay(1000);  // Pause for 1 second
}

Reference: ​

The reference and design files are listed below: