Build Instructions

Collapse

• 1

  CIRCUIT ASSEMBLY

  • The assembly process begins with applying solder paste to the pads of each SMD component using a solder paste dispenser syringe. I'm using SnPb 63/37 solder paste for this build.
  • Next, using ESD tweezers, I carefully pick and place each SMD component in its designated position. This includes passive components such as resistors and capacitors, the IP5306 power management IC, and the Waveshare RP2040 Tiny board.
  • Once all the SMD components are in place, the PCB goes onto a reflow hotplate, which heats the board from below until the solder paste reaches its melting temperature. The solder paste melts and forms electrical and mechanical connections, securing the components to the PCB.

  TESTING THE BOARD

  Before moving on to the through-hole components, I wanted to make sure the board was working correctly.

  I connected a bench power supply set to 5V to the board's charging input. The LED on the IP5306 power management IC started blinking, indicating that the power management circuit was responding. The RP2040 also booted up and ran its default demo code, which cycles through different RGB LED colours.

  With the initial testing complete, it was time to move on to the through-hole assembly.

  • The next step was to place all the through-hole components, including the DFPlayer Mini, USB Type-C port, rocker switch, and MPU6050 module.
  • After positioning all the components, I flipped the PCB over and soldered their leads using a soldering iron.
  • Finally, I trimmed the excess leads from all the through-hole components. This is particularly important for this project because the PCB needs to fit inside the 3D-printed sword, where space is limited.
• 2

  CIRCUIT TEST—DF MINI PLAYER

  #include "Arduino.h"
  #include "DFRobotDFPlayerMini.h"
  
  // Create the DFPlayer object
  DFRobotDFPlayerMini myDFPlayer;
  
  void setup() {
    // Initialize hardware serial for RP2040 on GP0 (TX) and GP1 (RX)
    Serial1.begin(9600);
    Serial.begin(115200);
    
    // Give the DFPlayer 2 seconds to boot and mount the SD card
    delay(2000); 
  
    Serial.println("Starting DFPlayer Mini...");
  
    // Initialize the DFPlayer and bind it to Serial1
    if (!myDFPlayer.begin(Serial1)) {
      Serial.println("DFPlayer error! Check RX/TX wiring.");
      while(true); // Stop here if it fails
    }
  
    Serial.println("DFPlayer Online.");
  
    // 1. Set volume (0 to 30) - Set to 20 for testing
    myDFPlayer.volume(20); 
    delay(500);
  
    // 2. Play Track 1 (The Slash - 0001.mp3)
    Serial.println("Playing Track 1...");
    myDFPlayer.play(1); 
    
    // 3. Wait exactly 2 seconds
    delay(2000); 
  
    // 4. Play Track 2 (Aragorn Theme - 0002.mp3)
    Serial.println("Playing Track 2...");
    myDFPlayer.play(2); 
    delay(500); // Give the chip a moment to load the new track
  
    // 5. Turn on looping for the theme
    Serial.println("Looping Track 2...");
    myDFPlayer.enableLoop(); 
  }
  
  void loop() {
    // Empty! The DFPlayer handles the audio looping completely on its own.
  }

  For this test, I used two MP3 files stored on the microSD card: 0001.mp3, which contains the metallic sword-clash sound effect, and 0002.mp3, which plays the Aragorn theme.

  The demo sketch initializes the DFPlayer Mini over UART using the RP2040 Tiny's Serial1 interface, sets the playback volume to 20 out of 30, and starts playing the first track. After two seconds, it switches to the second track and enables looping so the Aragorn theme continues playing.

  To test the setup, I connected power to the Waveshare RP2040 Tiny board. Once the DFPlayer Mini initialized and the SD card was ready, playback started automatically. This confirmed that the audio module, speaker, and serial communication were working correctly.

• 3

  CIRCUIT TEST—MPU6050

  #include <Wire.h>
  #include <Adafruit_MPU6050.h>
  #include <Adafruit_Sensor.h>
  
  Adafruit_MPU6050 mpu;
  
  void setup() {
    Serial.begin(115200);
    
    // Initialize I2C on the RP2040-Tiny specific pins
    Wire.setSDA(4);
    Wire.setSCL(5);
    Wire.begin();
  
    Serial.println("Searching for MPU6050...");
  
    // Try to initialize the sensor
    if (!mpu.begin()) {
      Serial.println("Failed to find MPU6050 chip! Check GP4/GP5 wiring.");
      while (1) {
        delay(10); // Halt here if sensor isn't found
      }
    }
    
    Serial.println("MPU6050 Found!");
  
    // Set the accelerometer range to 8G (perfect for detecting sword swings)
    mpu.setAccelerometerRange(MPU6050_RANGE_8_G);
    
    // Print the legend for the Serial Plotter
    Serial.println("Accel_X,Accel_Y,Accel_Z,Total_Force");
  }
  
  void loop() {
    // Get fresh data from the sensor
    sensors_event_t a, g, temp;
    mpu.getEvent(&a, &g, &temp);
  
    // Read the individual axes (in m/s^2)
    float x = a.acceleration.x;
    float y = a.acceleration.y;
    float z = a.acceleration.z;
  
    // Calculate the total force magnitude (this is what we will use to trigger the woosh)
    float total_force = sqrt((x * x) + (y * y) + (z * z));
  
    // Print the data separated by commas for the Serial Plotter
    Serial.print(x);
    Serial.print(",");
    Serial.print(y);
    Serial.print(",");
    Serial.print(z);
    Serial.print(",");
    Serial.println(total_force);
  
    // A 20ms delay gives a smooth 50Hz graph on the plotter
    delay(20); 
  }

  We use the above demo sketch to test the MPU6050 accelerometer and gyroscope using the Waveshare RP2040 Tiny board.

  The code initializes the sensor over I²C using GPIO 4 (SDA) and GPIO 5 (SCL), then continuously reads acceleration data across the X, Y, and Z axes. It also calculates the total acceleration magnitude and sends all four values to the Arduino Serial Plotter at a sampling rate of approximately 50 Hz.

  By moving and swinging the circuit like a sword, I could observe how the acceleration values change in real time. This helped verify that the sensor was working correctly and gave me a better idea of how to detect sword swings for triggering the metallic sound effects.

  Once the sensor was verified, the next step was to use these readings to trigger different audio tracks through the DFPlayer Mini, depending on the intensity of the swing.

View all 20 instructions