Fab Academy 2025

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Week 10 - Output Devices ​

Assignments of the Week ​

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

Individual Assignment ​

The assignment for this week plans to use Fusion 360 to design a simple PCB that can test output devices such as servos and WS2812, and process it using the Roland EGX-300.

1. Fusion 360 Design ​

  1. Schematic:
  2. PCB Document:
  3. 3D PCB:

2. Manufacturing ​

  1. Import .stl file

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

  3. Choose the type of process finishing

  4. Select cutting surface

  5. Use a 0.5mm milling cutter

  6. Use the default processing area.

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

  8. Set the XY speed to 3mm/sec

  9. Generate toolpath

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

  11. Start machining

  1. Picture after machining completion
  • The machined PCB has some issues where the holes and traces are not connected. However, simulations show that these parts are connected. It is speculated that this may be due to an oversized milling cutter diameter or improper parameter settings. We plan to attempt machining with a 0.2mm milling cutter to verify and resolve this issue.
  1. Picture after soldering completion

3. Functional Testing： ​

  1. Use XIAO ESP32 C3 to control WS2812 color change.

  • PIN configuration

  • PIN function

  • Add the Adafruit_NeoPixel.h library.

  • The effect after the code is uploaded and executed.

  • 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

  • Schematic Diagram

  • 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°.

  • The servo motor swings back and forth between 0° and 180°, with the following operation 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
}

Group Assignment ​

The group assignment for this week is to measure the power consumption of an output device.

  1. First, you need to know the formula for calculating power:

    𝑃 = 𝑈 × 𝐼

    P is power, measured in watts (W)

    U is voltage, measured in volts (V)

    I is current, measured in amperes (A)

  2. Calculate the actual power consumption: I used an adjustable power supply to independently power the WS2812, while the XIAO ESP32-C3 is only responsible for signal control. Both share a common ground to ensure the signal is transmitted correctly.

Based on the adjustable power supply information, the voltage is 5V and the current is 0.236A. Using the formula, the power consumption is calculated as:

𝑃=5𝑉×0.236𝐴=1.18𝑊

Thus, it is concluded that the power required to illuminate 18 WS2812 LEDs is 1.18W.

All related files and resources can be found in my Google Drive:

https://drive.google.com/drive/folders/10W-X8q_psMy1sCo13kEEVrAP6ympdVLi?usp=drive_link