Learn how to build Arduino Uno with an IC (74HC595)

I made a Running LED Bar Graph using Arduino:

Here is the video:

Here is the code:

int latchPin = 12; // Pin connected to ST_CP of 74HC595（Pin12）
int clockPin = 13; // Pin connected to SH_CP of 74HC595（Pin11）
int dataPin = 11; // Pin connected to DS of 74HC595（Pin14）
void setup() {
 // set pins to output
 pinMode(latchPin, OUTPUT);
 pinMode(clockPin, OUTPUT);
 pinMode(dataPin, OUTPUT);
}
void loop() {
 // Define a one-byte variable to use the 8 bits to represent the state of 8 LEDs of LED bar graph.
 // This variable is assigned to 0x01, that is binary 00000001, which indicates only one LED light on.
 byte x = 0x01;
 for (int j = 0; j < 8; j++) {
 // Output low level to latchPin
 digitalWrite(latchPin, LOW);
 // Send serial data to 74HC595
 shiftOut(dataPin, clockPin, LSBFIRST, x);
 // Output high level to latchPin, and 74HC595 will update the data to the parallel output port.
 digitalWrite(latchPin, HIGH);
 // make the variable move one bit to left once, then the bright LED move one step to the left once.
 x <<= 1;
 delay(100);
 }
}

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