INTREFACING SHIFT REGISTER WITH ARDUINO

This document gives some detail about how to interface shift register with Arduino, and connecting 7 segment display with it.

SCHEMATIC:

The schematic above shows shift register IC74HC595.It has 16pins. Vcc=5V.1 Micro Farad Capacitor is used. In this one shift register is used, we have to use at least two shift register and two 7 segment display.

                            
 

PINS 1-7, 15	Q0 " Q7	Output Pins
PIN 8	GND	Ground, Vss
PIN 9	Q7"	Serial Out
PIN 10	MR	Master Reclear, active low
PIN 11	SH_CP	Shift register clock pin
PIN 12	ST_CP	Storage register clock pin (latch pin)
PIN 13	OE	Output enable, active low
PIN 14	DS	Serial data input
PIN 16	Vcc	Positive supply voltage

 

 

 

 

 

 

 

 

 

 

The schematic above shows 7 segment display either common Anode or common Cathode (here it is common Anode).

Program:

 

//Pin connected to ST_CP of 74HC595

 

int latchPin = 8;

 

//Pin connected to SH_CP of 74HC595

 

int clockPin = 12;

 

////Pin connected to DS of 74HC595

 

int dataPin = 11;

 

//Initializing the output pins

 

int k=B11111111;

 

int a;

 

 

void setup()

{

 

//set pins to output so you can control the shift register

 

pinMode(latchPin, OUTPUT);

 

 

pinMode(clockPin, OUTPUT);

 

 

pinMode(dataPin, OUTPUT);

 

 

Serial.begin(9600);

 

 

}

 

 

void loop()

 

{

 

// setting the output pins to show 1

 

k=B11111010;

\

// making latch pin low to shift

 

digitalWrite(latchPin, LOW);

 

// shift out the bits:

 

shiftOut(dataPin, clockPin, MSBFIRST, k);

 

// making latch pin high to store

 

digitalWrite(latchPin, HIGH);

 

 

delay(1000);

 

// print the value

 

Serial.print(k);

 

// setting the output pins to show 2

 

k=B10100100;

 

// making latch pin low to shift

 

 

digitalWrite(latchPin, LOW);

 

// shift out the bits: 

 

shiftOut(dataPin, clockPin, MSBFIRST, k);

 

// making latch pin high to store

 

 

digitalWrite(latchPin, HIGH);

 

delay(1000);

 

// print the value

 

Serial.print(k);

 

// setting the output pins to show 3

 

 

k=B10110000;

 

// making latch pin low to shift

 

 

digitalWrite(latchPin, LOW);

 

// shift out the bits:

 

 

shiftOut(dataPin, clockPin, MSBFIRST, k);

 

// making latch pin high to store

 

digitalWrite(latchPin, HIGH);

 

delay(1000);

 

// print the value

 

 

Serial.print(k);

 

// setting the output pins to show 4

 

 

 

k=B10011010;

 

// making latch pin low to shift

 

 

digitalWrite(latchPin, LOW);

 

// shift out the bits:

 

 

shiftOut(dataPin, clockPin, MSBFIRST, k);

 

// making latch pin high to store

 

 

digitalWrite(latchPin, HIGH);

 

 

delay(1000);

 

 

// print the value

 

 

Serial.print(k);

 

 

 

// setting the output pins to show 5

 

 

k=B10010001;

 

 

// making latch pin low to shift

 

digitalWrite(latchPin, LOW);

 

// shift out the bits:

 

 

shiftOut(dataPin, clockPin, MSBFIRST, k);

 

// making latch pin high to store

 

 

digitalWrite(latchPin, HIGH);

 

 

delay(1000);

 

// print the value

 

 

Serial.print(k);

 

// setting the output pins to show 6

 

k=B10000001;

 

// making latch pin low to shift

 

 

digitalWrite(latchPin, LOW);

 

// shift out the bits:

 

 

shiftOut(dataPin, clockPin, MSBFIRST, k);

 

 

// making latch pin high to store

 

 

digitalWrite(latchPin, HIGH);

 

 

delay(1000);

 

 

// print the value

 

 

Serial.print(k);

 

// setting the output pins to show 7

 

k=B11111000;

 

// making latch pin low to shift

 

digitalWrite(latchPin, LOW);

 

 

// shift out the bits:

 

 

shiftOut(dataPin, clockPin, MSBFIRST, k);

 

 

// making latch pin high to store

 

 

digitalWrite(latchPin, HIGH);

 

 

delay(1000);

 

// print the value

 

 

Serial.print(k);

 

// setting the output pins to show 8

 

k=B10000000;

 

// making latch pin low to shift

 

digitalWrite(latchPin, LOW);

 

// shift out the bits:

 

 

shiftOut(dataPin, clockPin, MSBFIRST, k);

 

// making latch pin high to store

 

digitalWrite(latchPin, HIGH);

 

 

delay(1000);

 

// print the value

 

 

Serial.print(k);

 

// setting the output pins to show 9

 

k=B10010000;

 

// making latch pin low to shift

 

digitalWrite(latchPin, LOW);

 

 

// shift out the bits:

 

 

shiftOut(dataPin, clockPin, MSBFIRST, k);

 

// making latch pin high to store

 

 

digitalWrite(latchPin, HIGH);

 

 

delay(1000);

 

 

// print the value

 

 

Serial.print(k);

 

 

// setting the output pins to show 0

 

 

k=B11000000;

 

 

// making latch pin low to shift

 

 

digitalWrite(latchPin, LOW);

 

 

// shift out the bits:

 

 

 

shiftOut(dataPin, clockPin, MSBFIRST, k);

 

 

// making latch pin high to store

 

 

digitalWrite(latchPin, HIGH);

 

 

delay(1000);

 

 

// print the value

 

 

Serial.print(k);

 

 

 

 

 

}

 

 

 

 

 

CONNECTING SHIFT REGISTER WITH ARDUINO:

 

 

 

 

 

If we want to use more than one shift register, we have to connect the Q7" (PIN 9) of the first shift register to the serial input pin (PIN 14) of the next shift register. If we want to connect more shift register the same (i.e. connecting the PIN 14 of the shift register with the PIN 9 of the previous shift register) procedure must be followed. connecting two shift register is shown below