Smart Doorbell
The Smart Doorbell project allows the user to interact with environment with both input and output modules. The Ultrasonic Distance Sensor Module is used to detect if there is a person or a hand in front of the doorbell. If anything is near it, it detects and sends a feedback to script, allowing the user to play a sound with a buzzer.
About Tools and Materials:
SMD USB Gateway (Purchase Here)
Arduino Gateway Module (Purchase Here)
Ultrasonic Distance Sensor Module (Purchase Here)
Step 1: Hardware & Software Overview
Project Key Components
The SMD acts as a bridge between the script and the modules. It is responsible for interpreting the commands sent by the script and translating them into actions that read input from the Ultrasonic Distance Sensor Module and play an alert sound with the Buzzer Module.
The Buzzer Module is connected to the system for the most crucial role for the application, that is alerting the user when something is nearby.
Ultrasonic Distance Sensor Module
The Ultrasonic Distance Sensor Module is used to detect if anything is nearby and if there is, how many centimeters away.
The SMD library is at the heart of the application. It communicates with the SMD using a specific communication protocol, sending commands to read the Ultrasonic Distance Sensor Module and play an alert sound with the Buzzer Module.
Project Key Features
Proximity-Based Activation
The project uses the module with the HC-SR04 to detect the surroundings via ultrasonic sound waves. It makes a great way to understand how physics of sound works and also see that it is a way of interacting with environment with such an input sensor.
Adjustable Sensitivity
The user can change the sensivity of the distance check, customizing it to be more sensitive or unresponsive to near surroundings.
Real-time Monitoring
The script can easily provide the real-time distance monitoring if the user add a simple line. It enhances the code and gives more opportunity to monitor the surroundings.
Step 2: Assemble
Getting Started
Hardware Setup
Connect the SMD to the PC or Arduino board using USB Gateway Module or Arduino Gateway Module.
Connect the Ultrasonic Distance Sensor Module and the Buzzer Module to the SMD using an RJ-45 cable.
Make sure that the SMD is powered and all connections are correct.
Project Wiring Diagram

Step 3: Run & Test
Run the Script
Run the script on your computer. This will establish communication with the SMD and initiate control of the Ultrasonic Distance Sensor Module and the Buzzer Module.
Observe Buzzer Activation
Use an object or a hand to trigger the Ultrasonic Distance Sensor Module, if it will detect an obstacle in the specified range, the script will send a signal to the Buzzer Module to alert the user.
Codes
from serial.tools.list_ports import comports
from platform import system
from smd.red import *
baudrate = 115200 # Baud rate of communication
ID = 0 # ID of the SMD
buzzer_module_id = 5 # ID of the buzzer module
distance_module_id = 1 # ID of the ultrasonic distance sensor module
def USB_Port():
"""
Scans and identifies a compatible USB port for the current operating system.
Returns:
str: The detected USB port or None if no suitable port is found.
"""
# Get a list of available ports
ports = list(comports())
# Known USB port names for different operating systems
usb_names = {
"Windows": ["USB Serial Port"], # Names specific to Windows
"Linux": ["/dev/ttyUSB"], # Names specific to Linux
"Darwin": [ # Names specific to macOS
"/dev/tty.usbserial",
"/dev/tty.usbmodem",
"/dev/tty.SLAB_USBtoUART",
"/dev/tty.wchusbserial",
"/dev/cu.usbserial",
]
}
# Detect the operating system
os_name = system()
print(f"Operating System: {os_name}")
if ports:
for port in ports:
# Check if the port matches any known USB names
if any(name in port.device or name in port.description for name in usb_names.get(os_name, [])):
print(f"USB device detected on port: {port.device}")
return port.device # Return the first matching port
# If no suitable port is found, print the list of available ports
print("No suitable USB device found. Available ports:")
for port in ports:
print(f"Port: {port.device}, Description: {port.description}, HWID: {port.hwid}")
else:
print("No ports detected!")
return None
try:
# Find a valid serial port
SerialPort = USB_Port()
if not SerialPort:
raise Exception("No compatible USB port found. Please check your connection.")
print(f"Using serial port: {SerialPort}")
# Initialize the SMD module
master = Master(SerialPort, baudrate) # Defines the USB gateway module
master.attach(Red(ID)) # Gives access to the SMD of specified ID
master.scan_modules(ID) # Scans and identifies the modules connected to the SMD
# Main loop
while True:
# Get distance data from the ultrasonic sensor
distance = master.get_distance(ID, distance_module_id) # Variable to store the distance data
print(f"Distance: {distance} cm") # Print the value to observe
if distance < 15:
# Set the buzzer frequency to 600 Hz
master.set_buzzer(ID, buzzer_module_id, 600) # Number corresponds to the frequency of the buzzer
else:
# Turn off the buzzer
master.set_buzzer(ID, buzzer_module_id, 0) # Sets the buzzer frequency to 0
except Exception as e:
print(f"Error: {e}")
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