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Shiftbit registers can be a little tricky to setup so I designed this simple Hello World code for doing just that. This example uses a 74HC595 Shift Register in conjunction with a common anode seven segment display. This code is designed to shift the "HIGH" value on the Shift Bit Register from Q0-Q7. This is achieved by sending the values 1,2,4,…
/*
********************************************************************
Name : shiftOutDisplay, Test code
Author : Benjo Charlie
Date : 13 Sept, 2013
Version : 1.0
Notes : Shiftbit registers can be a little tricky to setup so I
: designed this simple Hello World code for doing just that.
: This example uses a 74HC595 Shift Bit Register in conjunction
: with a common anode seven segment display.
: This code sends the following values to a Shift Bit Register:
: 1, 2, 4, 8, 16, 32, 64, 128.
: Each of the 74HC595 outputs will "switch on" in turn.
********************************************************************
7 Segment (Common Anode) Display Map: (This can be altered to reflect your HW)
D E 5V F G
___|___|___|___|___|____
| |
| F |
| E G |
| D |
| A C |
| B H(Dot) |
|________________________|
| | | | |
A B 5V C H
74HC595 Map:
_______
OUT Q1-|1 * 16|-5V
OUT Q2-|2 15|-OUT Q0
OUT Q3-|3 14|-ARD PIN 11
OUT Q4-|4 13|-GND
OUT Q5-|5 12|-ARD PIN 8 ; 1uF TO GND
OUT Q6-|6 11|-ARD PIN 12
OUT Q7-|7 10|-5V
GND-|8_____9|-
********************************************************************
*/
//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;
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() {
// integer to represent the "Q" pin on the Shift Bit Register.
int shiftBitRegPin=0;
// The following for loop will Shift the "HIGH" value on the Shift Bit Register from Q0-Q7.
// This is achieved by sending the values 1,2,4,8,16,32,64,128
// The Binary equivalent is as follows (Notice the bit movement):
// 0000 0001, 0000 0010, 0000 0100, 0000 1000, 0001 0000, 0010 0000, 0100 0000, 1000 0000
// NB. The operator << could be replaced with *2 if that helps with understanding.
for (int shiftBitRegOut = 1; shiftBitRegOut < 256; shiftBitRegOut = shiftBitRegOut << 1) {
// take the latchPin low so the output
// doesn't change while you're sending in bits:
digitalWrite(latchPin, LOW);
// shift out the bits:
shiftOut(dataPin, clockPin, MSBFIRST, shiftBitRegOut);
//take the latch pin high so the LEDs will light up:
digitalWrite(latchPin, HIGH);
// Print out the Shift Bit Register pin with it's corresponding value.
Serial.print("Q");
Serial.print(shiftBitRegPin);
Serial.print(" = ");
Serial.println(shiftBitRegOut);
Serial.print("Binary = ");
Serial.println(shiftBitRegOut, BIN);
Serial.println("****************");
// Increment the pin number by 1 but do not exceed 7
if (shiftBitRegPin>=7) {
shiftBitRegPin=0;
} else {
shiftBitRegPin++;
}
delay(4000);
}
}
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