LED Bar Graph Display using Arduino Uno

 

Circuit Diagram

Program Logic:

The sketch sets the pins connected to the LEDs as outputs, and then defines a function to turn all the LEDs off at the same time. This function is called in the loop cycle to turn the LEDs off, and then the LEDs are turned on one at a time with a 200-millisecond delay between each one to create a sweeping effect. Another loop sends the sequence back the other way

Program Code

void setup() {

for (int i = 2; i < 10; i++) { // Choose pins 2-9

pinMode(i, OUTPUT); // Set the pins as outputs

}

}

// Define function to turn off all LEDs at the same time

void allLEDsOff(void) {

for (int i = 2; i < 10; i++) {

digitalWrite(i, LOW);

}

}

// Switch on LEDs in sequence from left to right

void loop() {

for (int i = 2; i < 9; i++) { // Run loop once for each LED

allLEDsOff(); // Turn off all LEDs

digitalWrite(i, HIGH); // Turn on current LED

delay(200); // Delay of 200 ms,

// then repeat loop to move on to next LED

}

for (int i = 9; i > 2; i--) { // Light LEDs from right to left

allLEDsOff();

digitalWrite(i, HIGH);

delay(200);

}

}