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Sun Shift LED Bar

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The 74HC595 shift register controls a 10 LED Bar Graph.

Let there be LEDs! The Sun Shift Bar controls 10 LEDs with a 74HC595 shift register. The shift register needs just 3 wires to control 8 different outputs. Annoyingly, the LED bar has 10 different LEDs while the shift register has only 8 output pins. We solve this issue by doubling up the last 4 LEDs in the LED Bar. This way, the first 6 outputs of the shift register each control a single LED, while the last two outputs of the register control 2 LEDs each. Watch the video for a visual explanation . We give Arduino code below to light up the LED Bar graph in a bunch of different lighting patterns, like chasers, blinkers, counters, etc. This PCB is ready to daisy chain so for the same 3 wires on your micro-controller you can control tons of LED bars. We silkscreened a sun and moon on this board to remind you this little PCB makes light-- a small example of onomatopoetic electronics . Want to learn more about shift registers? Check out our shift register tutorial .

Images

Sun Shift Bars play well with Arduinos

Sun Shift Bars play well with Arduinos

Easy to connect with Arduino!
Sun Shift Bar

Colorful wires! The 5 wires are Ground in blue and 5V in red, then DATA in orange, LATCH in yellow and CLOCK in green.
Red and Green

Comes with red or Green LED bars
Another View of Arduino Hookup

Show the score in your Arduino game with this LED Bar graph!
Sun Shift Bar

LEDs for miles!
Depth of field

LED Bars in the hazy distance.

Easy to connect with Arduino!

Video

Sun Shift Bar Video

Showing off the lighting modes from the code below as well as the ease with which these modules can be daisy chained!

LED Bar Graph Video

See all the lighting modes in action! Chaser, counter, blinker and more! Check the code below to make your own.

Code

Arduino Code for LED Bar Graph controlled by 74HC595 Shift Register

Below is code to cycle through several different lighting modes on an LED Bar graph controlled by a 74HC595 shift register. The code to do a chaser goes like this:

for (int i = 0; i < 8; i++) {    // latchPin low so LEDs don't change     // while you are sending in bits:    byte curb = 1 << i;    digitalWrite(latchPin, LOW);     shiftOut(dataPin, clockPin,  curb);     digitalWrite(latchPin, HIGH);    delay(i*50);  }

We write consecutive powers of two out to the LED Bar Graph. Every power of two in binary is a single one and all the rest 0s. So if we write 1,2,4,8,16 we will see a single LED illuminated and it will seem to walk up or down The LED's as if its chasing itself. We get the consecutive powers of two with this line:

byte curb = 1 << i;

the left shift operator (<< ) gives efficient access to exponentiation by 2. Shifting the number 1 i places to the left gives a binary number equal to 2 to the power i.Here is code to display what we call the filler lighting mode:

for (int i = 1; i <= 8; i++) {    // latchPin low so LEDs don't change     // while you are sending in bits:    byte curb = (1 << i)-1;    digitalWrite(latchPin, LOW);     shiftOut(dataPin, clockPin,  curb);     digitalWrite(latchPin, HIGH);    delay(200);  }

Just as any power of 2 represented in binary is a single 1 followed by 0s, any number exactly 1 less than a power of 2 is represented by all 1s up to the next order of magnitude bit. So we get those numbers: 1,3,7,15,31,63 in the line:

byte curb = (1 << i)-1;

If you just want all the LEDs to go on and off blinky style try this:

for (int i = 0; i <= 8; i++) {    digitalWrite(latchPin, LOW);     shiftOut(dataPin, clockPin,  255);     digitalWrite(latchPin, HIGH);    delay(150);    digitalWrite(latchPin, LOW);     shiftOut(dataPin, clockPin,  0);     digitalWrite(latchPin, HIGH);    delay(150);  }

You can change the for loop condition from 8 to however times you the the bar to blink.In this code we use a home-cooked shiftOut function, but you can just as well use the Arduino library's shiftOut . Enjoy! Let us know in the comments if you build anything cool with the code below!

Download File

/* LucidTronix Shift Register * LED chaser w/ 74HC595  * Tutorial at: * http://www.lucidtronix.com/tutorials/43 */int dataPin = 2; //Pin connected to DS of 74HC595 int latchPin = 3; //Pin connected to ST_CP of 74HC595int clockPin = 4; //Pin connected to SH_CP of 74HC595void setup() {  //set pins to output so you can control the shift register  pinMode(latchPin, OUTPUT);  pinMode(clockPin, OUTPUT);  pinMode(dataPin, OUTPUT);}void loop() {  for (int i = 0; i < 8; i++) {    // latchPin low so LEDs don't change     // while you are sending in bits:    byte curb = 1 << i;    digitalWrite(latchPin, LOW);     shiftOut(dataPin, clockPin,  curb);     digitalWrite(latchPin, HIGH);    delay(i*50);  }  for (int i = 1; i <= 8; i++) {    digitalWrite(latchPin, LOW);     shiftOut(dataPin, clockPin,  255);     digitalWrite(latchPin, HIGH);    delay(150);    digitalWrite(latchPin, LOW);     shiftOut(dataPin, clockPin,  0);     digitalWrite(latchPin, HIGH);    delay(150);  }  for (int i = 1; i <= 8; i++) {    // latchPin low so LEDs don't change     // while you are sending in bits:    byte curb = (1 << i)-1;    digitalWrite(latchPin, LOW);     shiftOut(dataPin, clockPin,  curb);     digitalWrite(latchPin, HIGH);    delay(200);  }  for (int i = 0; i < 8; i++) {    // latchPin low so LEDs don't change     // while you are sending in bits:    digitalWrite(latchPin, LOW);     shiftOut(dataPin, clockPin,  random(0,255));     digitalWrite(latchPin, HIGH);    delay(150);  }  for (int i = 0; i < 256; i++) {    // latchPin low so LEDs don't change     // while you are sending in bits:    digitalWrite(latchPin, LOW);     shiftOut(dataPin, clockPin, i);     digitalWrite(latchPin, HIGH);    delay(30);  }}// Shifts 8 bits out MSB first, on rising clock edgevoid shiftOut(int myDataPin, int myClockPin, byte myDataOut) {  int i=0;  int pinState;  pinMode(myClockPin, OUTPUT);  pinMode(myDataPin, OUTPUT);  digitalWrite(myDataPin, 0);  digitalWrite(myClockPin, 0);   for (i=7; i>=0; i--)  {    digitalWrite(myClockPin, 0);    if ( myDataOut & (1<

Parts

parts

Parts

Title	Description	#	Cost	Link	Picture
74HC595 PCB	This PCB maps the 74HC595 shift register chip to an LED bar.	1	$1.5	Link
LED Bar Graph	10 Red LEDs in a line.Value:Red	1	$1.26	Link
Shift Register	IC SHIFT REGISTER 8BIT 16-SOP Tri-State Serial to ParallelValue:74HC	1	$0.65	Link
Resistors	RES 300 OHM 1/8W 5% 0805 SMDValue:300	2	$0.1	Link
Resistor Array	RES ARRAY 300 OHM 4 RES 1206Value:300	2	$0.02	Link

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