/* Define shift register pins used for seven segment display */
#define LATCH_DIO 4
#define CLK_DIO 7
#define DATA_DIO 8

#define Pot1 0

/* Segment byte maps for numbers 0 to 9 */
const byte SEGMENT_MAP[] = {0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0X80,0X90};
/* Byte maps to select digit 1 to 4 */
const byte SEGMENT_SELECT[] = {0xF1,0xF2,0xF4,0xF8};

void setup ()
{
Serial.begin(9600);
/* Set DIO pins to outputs */
pinMode(LATCH_DIO,OUTPUT);
pinMode(CLK_DIO,OUTPUT);
pinMode(DATA_DIO,OUTPUT);
}

/* Main program */
void loop()
{
int PotValue;
PotValue = analogRead(Pot1);
Serial.print("Potentiometer: ");
Serial.println(PotValue);
/* Update the display with the current counter value */
for (int i = 10;i >0; i--)
{
WriteNumberToSegment(0 , PotValue / 1000);
WriteNumberToSegment(1 , (PotValue / 100) % 10);
WriteNumberToSegment(2 , (PotValue / 10) % 10);
WriteNumberToSegment(3 , PotValue % 10);
}

}

/* Write a decimal number between 0 and 9 to one of the 4 digits of the display */
void WriteNumberToSegment(byte Segment, byte Value)
{
digitalWrite(LATCH_DIO,LOW);
shiftOut(DATA_DIO, CLK_DIO, MSBFIRST, SEGMENT_MAP[Value]);
shiftOut(DATA_DIO, CLK_DIO, MSBFIRST, SEGMENT_SELECT[Segment] );
digitalWrite(LATCH_DIO,HIGH);
}