Wii Balance Board Scale

wii-scale.py

import os
import struct
import time
import numpy as np
import pyfiglet  # For ASCII art text

# Path to the joystick device
JOYSTICK_DEVICE = "/dev/input/js0"

# Joystick event format
EVENT_FORMAT = "IhBB"
EVENT_SIZE = struct.calcsize(EVENT_FORMAT)

# Polynomial coefficients from np.polyfit
POLY_COEFF = [1.89584106e-08, 9.73656453e-03, 5.30274624]  # Replace with your coefficients
poly_func = np.poly1d(POLY_COEFF)

def open_joystick(device_path):
    """Open the joystick device."""
    try:
        return open(device_path, "rb")
    except FileNotFoundError:
        print(f"Joystick device not found at {device_path}.")
        return None

def process_joystick_event(event):
    """Process a single joystick event."""
    timestamp, value, event_type, axis_number = struct.unpack(EVENT_FORMAT, event)

    # Only process axis events (event type 2)
    if event_type == 2:  # 2 is for axis events
        return axis_number, value
    return None, None

def estimate_weight(total_load):
    """Estimate weight using the polynomial calibration model."""
    return poly_func(total_load)

def main():
    # Open the joystick device
    js_device = open_joystick(JOYSTICK_DEVICE)
    if not js_device:
        return

    print("Reading data from the Wii Balance Board...")
    try:
        # Baseline values for each axis
        baselines = [-32767] * 4  # Assuming 4 axes
        relative_loads = [0] * 4

        # Variables for averaging
        total_loads = []  # Accumulates total loads for averaging
        start_time = time.time()

        while True:
            event = js_device.read(EVENT_SIZE)
            if event:
                axis_number, value = process_joystick_event(event)
                if axis_number is not None and axis_number < 4:
                    # Calculate relative load
                    relative_load = value - baselines[axis_number]
                    relative_loads[axis_number] = relative_load

                    # Calculate total load
                    total_load = sum(relative_loads)
                    total_loads.append(total_load)

            # Every 5 seconds, calculate and print the average
            if time.time() - start_time >= 5:
                if total_loads:
                    avg_total_load = sum(total_loads) / len(total_loads)
                    avg_weight_kg = estimate_weight(avg_total_load)
                    avg_weight_lbs = avg_weight_kg * 2.20462

                    # Clear the screen for a clean display
                    os.system('clear')

                    # Print large ASCII text for weight
                    ascii_weight = pyfiglet.figlet_format(f"{avg_weight_lbs:.2f} lbs")
                    print(ascii_weight)

                    # Print regular details
                    print(f"Average Total Load (5s): {avg_total_load:.2f}")
                    print(f"Estimated Average Weight (5s): {avg_weight_kg:.2f} kg ({avg_weight_lbs:.2f} lbs)")

                # Reset for the next interval
                total_loads = []
                start_time = time.time()

            time.sleep(0.01)
    except KeyboardInterrupt:
        print("\nExiting...")
    finally:
        js_device.close()

if __name__ == "__main__":
    main()