<h3>Components Used</h3>Arduino UNO Development Board: The central processing unit that controls the LED matrix.LEDs (64): Arranged in an 8x8 grid to form the matrix display.10Ω Resistors (8): Used to limit the current flowing through each LED, preventing damage and ensuring consistent brightness. <h3>Code Analysis</h3>The code is structured into several key sections: defining pin connections, setting up the Arduino board, the main loop for the heartbeat effect, and functions to control the LED matrix.1. Pin Definitions:led_row and led_col arrays define the pins connected to the rows and columns of the LED matrix, respectively.2. LED Coordinates:coords_1 array contains the coordinates for the first heart shape.coords_2 array contains the coordinates for the second heart shape, which is used to create the new effect of lighting up all LEDs within the heart contour.3. Setup Function:Initializes all the row and column pins as outputs, setting the stage for controlling the LED matrix.4. Loop Function:The loop() function now includes an additional loop to handle the new effect. It iterates through the coords_1 array for the first heart shape, then reverses the direction for the second part of the heartbeat, and finally iterates through the coords_2 array to light up all LEDs within the heart contour.5. Reset Function:reset_all() turns off the entire LED matrix by setting all row pins low and all column pins high.6. Display Function:display() lights up a single LED at the specified coordinates.display_all() lights up all LEDs within a specified row (y) from column x1 to column x2, effectively lighting up the area enclosed by the heart contour.7. Speed Adjustment:The delay() in the display() and display_all() functions adjust the speed of the heartbeat effect. This can be modified to make the effect faster or slower. <h3>How It Works</h3>When the Arduino board is powered and the code is executed, the loop() function continuously iterates through the code[] array, lighting up LEDs in a sequence that forms a heart shape. The forward and backward iteration through the array creates the effect of the heart "beating." The reset_all() function ensures that the matrix is cleared before each new heartbeat cycle, and the display() and display_all() functions manage the individual lighting of LEDs based on their coordinates.

8x8 LED Matrix

<h3>Components Required</h3>	Arduino UNO Development Board: The brain of the project that will read inputs from the keypad and control the LEDs.	LEDs (9): To form a 3x3 LED matrix for visual feedback.	Push Buttons (9): To form a 3x3 keypad matrix for user input.	Resistors: To limit the current and prevent damage for LEDs. <h3>Code Analysis</h3>The code provided is a straightforward implementation of the project requirements. Let's break down the key parts of the code:	1.Pins Definition:		led_row &nbsp;and led_col arrays define the pins connected to the rows and columns of the LED matrix.		btn_row and btn_col arrays define the pins connected to the rows and columns of the keypad matrix.	2.Setup Function:		Initializes all the keypad row pins as outputs and column pins as inputs.		Initializes all the LED row pins as outputs and column pins as outputs.	3. Loop Function:		The loop() function contains the main logic of the project.		It performs row scanning by setting the current row's keypad buttons to high.		It then performs column scanning within each row. If a button is pressed (detected as high), the corresponding LED is lit up for 500 milliseconds.		After the delay, the LED is turned off, and the row is reset for the next scan. <h3>How It Works</h3>When the circuit is powered and the code is uploaded to the Arduino UNO, the device will continuously scan each row of the keypad matrix. When a button is pressed, the corresponding LED in the LED matrix will light up for a brief period, providing immediate visual feedback to the user. <h3>Additional Notes</h3>	Debounce Handling: The current implementation does not include debounce logic, which might be necessary in a real-world application to handle the mechanical bounce of buttons.	Enhancements: Additional features like multiple LED lighting patterns or interactive effects could be added to enhance user experience.	Scalability: The code structure allows for easy scaling up to larger matrices by adjusting the pin arrays and loop logic accordingly.

Key-controlled 3x3 LED Matrix

The Arduino code initializes the pin modes and continuously reads the potentiometer's value to adjust the LED's brightness. It also checks the push button's state to toggle between two blinking modes. The analogWrite() function is used to set the LED's brightness. The potentiometer's middle terminal voltage can be observed on an oscilloscope, showing a linear change as the knob is turned. The push button's signal can be monitored to see the transition between LOW and HIGH states when pressed and released.

LED Control

<h3>Pin Definitions</h3>The code begins by defining the pins connected to the shift registers:	dataPin&nbsp;(Pin A5): This is the serial data input pin for the shift register.	clockPin&nbsp;(Pin A4): This is the clock input pin for the shift register.	resetPin&nbsp;(Pin A3): This is the reset pin for the shift register, used to clear the register before sending new data. <h3>Display Characters</h3>The numbers array defines the hexadecimal codes for the digits 0 through 9 for a common cathode 7-segment display. These codes indicate which segments should be lit to display each digit. <h3>Setup Function</h3>In the setup function, all defined pins are set to output mode. <h3>Loop Function</h3>The loop function contains an infinite loop that calls the <code style="background-color: var(--color-brand-8); color: var(--brand-main);">displayNumber</code> function to display two digits on the 7-segment displays, with each digit being displayed for 1 second (1000 milliseconds). <h3>DisplayNumber Function</h3>The displayNumber function takes two parameters, num1 and num2, which are the digits to be displayed on the two 7-segment displays. The function first resets the shift register by pulling the reset pin low and then high. It then sends the data for each digit to the corresponding shift register and locks it in with the latch pin. <h3>ShiftOut Function</h3>The shiftOut function is used to send a byte of data to the shift register. It loops through 8 times, sending each bit of the data byte to the data pin and toggling the clock pin to shift the data.

Arduino-Controlled Dual 7-Segment LED Counters

In the circuit, the base of transistor BJT1 is stabilized at 13V by a voltage regulator diode. When the input voltage exceeds 13V, the output voltage remains almost unchanged regardless of how the input voltage is adjusted.

Series Voltage Regulator

Rc=(5V-2V)/10mA=300Ωβ=100 ----&gt; Ib=10mA/100=100uAVbe=0.7V ----&gt; Rb&lt;(3.3V-0.7V)/100uA=26kΩ

NPN LED driver

The project replicates the "Open Source Small TV Stand Project" from Yunmengze Entrepreneurial Space.Joining the official group can provide access to the full set of design reference documents.

 Desktop Weather Station

Materials Required:<ul><li>Arduino UNO board</li><li>LCD1602 display or HD44780</li><li>Push button</li><li>2、10kΩ resistor</li><li>Breadboard and jumper wires</li><li>USB cable to connect Arduino to a computer</li></ul>Circuit Connection:<ul data-checked="false"><li>Connect the LCD1602 or HD44780 Display:</li></ul><ul><li class="ql-indent-1">Connect the VSS pin to Arduino GND.</li><li class="ql-indent-1">Connect the VDD pin to Arduino 5V.</li><li class="ql-indent-1">Connect the VO pin to the A0 pin through a 2kΩ potentiometer to adjust contrast.</li><li class="ql-indent-1">Connect the RS pin to Arduino pin 12.</li><li class="ql-indent-1">Connect the RW pin to Arduino GND.</li><li class="ql-indent-1">Connect the EN pin to Arduino pin 11.</li><li class="ql-indent-1">Connect the D4 to D7 pins to Arduino pins 5, 4, 3, and 2 respectively.</li><li class="ql-indent-1">Connect the A pin to Arduino 5V and the K pin to Arduino GND to light the backlight.</li></ul><ul data-checked="false"><li>Connect the Push Button:</li></ul><ul><li class="ql-indent-1">Connect one end of the button to Arduino pin 7.</li><li class="ql-indent-1">Connect the other end to Arduino 5V through a 10kΩ resistor.</li><li class="ql-indent-1">Connect the middle terminal of the button to Arduino GND.</li></ul>rogramming the Arduino:The provided code handles the game logic, player movement, and obstacle generation. To upload the code to your Arduino board, follow these steps:<ol><li>Open the Arduino IDE on your computer.</li><li>Copy the provided code and paste it into a new sketch.</li><li>Select the correct Arduino board and port in the IDE.</li><li>Click the "Upload" button to compile and upload the code to the Arduino board.</li></ol>Operation Flow:<ul data-checked="false"><li>Power On:</li></ul><ul><li class="ql-indent-1">Connect the Arduino board to your computer via the USB cable and power it on.</li></ul><ul data-checked="false"><li>Game Initialization:</li></ul><ul><li class="ql-indent-1">The LCD will display "Avoid Obstacles!" for 2 seconds before clearing the screen.</li></ul><ul data-checked="false"><li>Playing the Game:</li></ul><ul><li class="ql-indent-1">Press and hold the button to make the player jump to the opposite row.</li><li class="ql-indent-1">Release the button to return the player to the original row.</li><li class="ql-indent-1">Obstacles will appear randomly in the rightmost columns of the first and second rows and will move leftward.</li><li class="ql-indent-1">The game ends if the player and an obstacle occupy the same column.</li></ul><ul data-checked="false"><li>Game Over:</li></ul><ul><li class="ql-indent-1">If a collision occurs, the LCD will display "Game Over!" for 2 seconds before resetting the game.</li></ul><ul data-checked="false"><li>Restarting the Game:</li></ul><ul><li class="ql-indent-1">After the game over screen, the game will automatically reset, and you can start playing again.</li></ul>

Arduino Obstacle Avoidance Game Circuit 

This project simulates a frequency meter using an Arduino UNO board. The circuit includes an LCD display and a switch. The LCD display's RS, EN, D4, D5, D6, and D7 pins are connected to Arduino UNO digital pins 12, 11, 7, 6, 5, and 4, respectively. A switch is connected to analog pin A0 of the Arduino UNO. When the switch detects a high signal, it triggers the Arduino UNO to start counting the pulses. The frequency is calculated by dividing 1000 by the average duration of the pulses. The result is displayed on the LCD, allowing users to read the frequency of the external signal source. This frequency meter can be used in various applications where pulse frequency measurement is required, such as in electronics testing, signal analysis, or educational demonstrations.

Frequency Meter Based on Arduino UNO

The circuit&nbsp;uses an inductor (L) and a capacitor (C) connected in parallel to generate oscillations. It operates on the principle of energy exchange between the electric field in the capacitor and the magnetic field in the inductor, producing a sinusoidal waveform at a frequency determined by the values of L and C.&nbsp;

Parallel LC Oscillator Circuit

In a circuit, when a reverse-biased diode is subjected to a reverse voltage that exceeds the breakdown voltage value, the diode will experience breakdown.

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