Improved Matilda

For this project you will build and assemble a 3D car that will have light sensitive headlights, siren sound in response to being shaken, and rotate 120 degrees when button A is pressed.

1) 3D Printer and Filament (any printer and filament that works for you will work)

2) Circuit Playground Express

3) Servo Motor

4) Alligator Clips

5) 4 Wheels 3D Printed

6) Body of Car

7) Hood/Roof of Car

8) Hot Glue Gun

Using these files, download them and import them into MakerBot as separate projects to print. Ensure that the body and roof of car are printed upside down (wheel inserts facing up for the body and the arms of the roof facing up) The wheels also should be printed on their sides. Printing like this will avoid using supports.

The following codes should be copied and pasted into Mu Editor to upload the functions of the CPX. For the following there are more instructions on Adafruits Instructions on Circuit Python.

import time

from adafruit_circuitplayground import cp

# Set the brightness of the NeoPixels

cp.pixels.brightness = 0.5

while True:

# Read light sensor value (0 is dark, 100 is bright roughly)

light_level = cp.light

# Adjust this threshold for what you consider "dark"

if light_level < 10:

# Turn all pixels white

cp.pixels.fill((255, 255, 255))

else:

# Turn all pixels off when it's not dark

cp.pixels.fill((0, 0, 0))

import time

from math import sqrt

from adafruit_circuitplayground import cp

# Siren settings

siren_frequencies = [440, 880] # Low and high tones

siren_delay = 0.1 # Delay between frequency changes

shake_threshold = 20 # Adjust for sensitivity

while True:

# Get x, y, z acceleration

x, y, z = cp.acceleration

total_accel = sqrt(x**2 + y**2 + z**2)

# Play siren while shaken

if total_accel > shake_threshold:

while total_accel > shake_threshold:

for freq in siren_frequencies:

cp.start_tone(freq)

time.sleep(siren_delay)

# Update acceleration to check if still shaking

x, y, z = cp.acceleration

total_accel = sqrt(x**2 + y**2 + z**2)

cp.stop_tone() # Stop when shaking stops

else:

time.sleep(0.05)

import time

import board

import pwmio

from adafruit_motor import servo

from adafruit_circuitplayground import cp

# Setup PWM for servo on pin A1

pwm = pwmio.PWMOut(board.A1, frequency=50)

my_servo = servo.Servo(pwm)

# Start at 0 degrees

my_servo.angle = 0

while True:

if cp.button_a:

my_servo.angle = 180 # Move servo to 180° when button A is pressed

time.sleep(0.3) # Small delay to debounce

elif cp.button_b:

my_servo.angle = 0 # Move servo back to 0° when button B is pressed

time.sleep(0.3) # Small delay to debounce

time.sleep(0.01) # Short delay to avoid excessive CPU usage

Using these codes, copy and past them into one page on the Mu Editor (make sure the page is labeled code.py). Once these codes are in a code.py page and your CPX is plugged into your computer, you can click the save button and then the load button to upload the functions to the CPX.

To set up the servo motor, you should grab 3 alligator clips, your CPX, and a servo motor. Use the 3 alligator clips and put the coordinated color wires as so: Ground wire --> GND, Power wire --> VOUT, and the Signal wire --> A2

You can also plug the black cord into the CPX and your computer instead of using a battery.

For the final assembly, glue the 4 wheels into their specified part of the body of the car. Then glue to hood of the car according to the attached photo. The CPX can be glued under the hood of the car, and the servo motor should be attached to the car by the arm to the underside of the car. The servo motor (the side thats not attached to the car) can also be attached to a platform to provide stability for the car.