Need someones help shorten the code i wrote.

Projects Programming
1

hi, im new to programming with the arduino and i wrote this code to do a simple knight rider led circuit with 2 shift registers and a led in between them, and i had to write out all the coding for it. I was wondering if there was any way to shorten the code i wrote, if you do know how to shorten it, could you also describe how you did it. thanks :smiley:

#define data 2
#define clock 3
#define data1 4
#define clock1 5

int time = 5;

byte a = B10000000;
byte b = B01000000;
byte c = B00100000;
byte d = B00010000;
byte e = B00001000;
byte f = B00000100;
byte g = B00000010;
byte h = B00000001;
byte i = B00000000;
byte j = B00000010;
byte k = B00000100;
byte l = B00001000;
byte m = B00010000;
byte n = B00100000;
byte o = B01000000;
byte p = B10000000;
byte q = B00000000;

void setup()
{
  pinMode(clock, OUTPUT); // make the clock pin an output
  pinMode(data , OUTPUT); // make the data pin an output3
  pinMode(data1, OUTPUT);
  pinMode(clock1, OUTPUT);
  pinMode(7, OUTPUT);
}

void loop()
{
  shift(a);
  shift(b);
  shift(c);
  shift(d);
  shift(e);
  shift(f);
  shift(g);
  shift(h);
  shift(i);
  flash(time);
  shift1(a);
  shift1(b);
  shift1(c);
  shift1(d);
  shift1(e);
  shift1(f);
  shift1(g);
  shift1(h);
  shift1(j);
  shift1(k);
  shift1(l);
  shift1(m);
  shift1(n);
  shift1(o);
  shift1(p);
  shift1(q);
  flash(time);
  shift(h);
  shift(j);
  shift(k);
  shift(l);
  shift(m);
  shift(n);
  shift(o);
}

void shift(int letter)
{
  shiftOut(data, clock, LSBFIRST, letter);
  delay (time);
}

void shift1(int letter)
{
  shiftOut(data1, clock1, LSBFIRST, letter);
  delay(time);
}

void flash(int duration)
{
  digitalWrite(7, HIGH);
  delay(duration);
  digitalWrite(7, LOW);
}
2

This won't reproduce your bit pattern exactly and I haven't got time to analyse why you have two clock pins, but it should give you an idea.

#define data 2
#define clock 3
#define data1 4
#define clock1 5

int time = 5;

void setup()
{
  pinMode(clock, OUTPUT); // make the clock pin an output
  pinMode(data , OUTPUT); // make the data pin an output3
  pinMode(data1, OUTPUT);
  pinMode(clock1, OUTPUT);
  pinMode(7, OUTPUT);
}

void loop()
{
   shift_to_the_right (clock);
   flash(time);
   shift_to_the_right (clock1);
   shift_to_the_left (clock1);
   flash(time);
   shift_to_the_left (clock);
}

void shift_to_the_right (int clockPin) {

   int x = B10000000;
	for (int i = 0; i < 8; i++) {
	    shift (x, clockPin);
	    x >>= 1;  // moved bit to next right position 
	}
}

void shift_to_the_left (int clockPin) {

   int x = B00000001;
	for (int i = 0; i < 8; i++) {
	    shift (x, clockPin);
	    x <<= 1;  // moved bit to next left position 
	}
}

void shift(int pattern, int clockPin)
{
  shiftOut(data, clockPin, LSBFIRST, pattern);
  delay (time);
}

void flash(int duration)
{
  digitalWrite(7, HIGH);
  delay(duration);
  digitalWrite(7, LOW);
}

Rob

3

thank you very much for your help with this but i was wondering how this line of code works,

for (int i = 0; i < 8; i++)

ive seen this line of code in alot of different projects but i don't know how it works, if you could explain or point me to a website of video that explains this, it would help alot.

also i have 2 data and clocks because i used 2 different 74HC164 shift registers to control the 16 leds that i have setup

thanks,
pdkkid

4

It just counts to 7

5

in plain English, what it says is "for variable i (which is an integer) start by making it equal to 0, then increment it by 1 until it gets to one integer less than 8 then stop doing whatever it is supposed to do.

Ain't C++ wonderful !!!

6

RPCoyle:
in plain English, what it says is "for variable i (which is an integer) start by making it equal to 0, then increment it by 1 until it gets to one integer less than 8 then stop doing whatever it is supposed to do.

Ain't C++ wonderful !!!

thank you very much, if you could tho help with with the rest of this code where i found it

void shift_to_the_right (int clockPin) {

   int x = B10000000;
	for (int i = 0; i < 8; i++) {
	    shift (x, clockPin);
	    x >>= 1;  // moved bit to next right position 
	}
}

again im wondering how this code outputs 1st B10000000 then it does B01000000. How does it move the 1 through it?.

7

How does it move the 1 through it?.

The

x >>= 1;  // moved bit to next right position

operation uses the >> shift to the right , hint read the comment.

8

The refence section of arduino.cc explains quite a lot of comon programming constructs.

furthermore a good book is about programming is - http://zanasi.chem.unisa.it/download/C.pdf - a must buy book BTW

9

Lookup table driven version.

Shorter code using data lookup table which could be placed in PROGMEM.

/* =====================================================================================================================
 * File - KnightRider.pde
 * ---------------------------------------------------------------------------------------------------------------------
 * <http://arduino.cc/forum/index.php/topic,107403.0.html>
 */

const uint8_t           pinDATA0    = 2;
const uint8_t           pinCLOCK0   = 3;
const uint8_t           pinDATA1    = 4;
const uint8_t           pinCLOCK1   = 5;

const uint8_t           pinFLASH    = 7;

const uint8_t           FLASH_OFF   = LOW;
const uint8_t           FLASH_ON    = HIGH;

const unsigned long     dmsLIT      = 5UL;      // delta, in milliseconds, LIGHT ON

const uint8_t           lookup[] =
{
      0b10000000    //  0
    , 0b01000000    //  1
    , 0b00100000    //  2
    , 0b00010000    //  3
    , 0b00001000    //  4
    , 0b00000100    //  5
    , 0b00000010    //  6
    , 0b00000001    //  7

    , 0b00000000    //  8       flash and change register set
    
    , 0b10000000    //  9
    , 0b01000000    // 10
    , 0b00100000    // 11
    , 0b00010000    // 12
    , 0b00001000    // 13
    , 0b00000100    // 14
    , 0b00000010    // 15
    , 0b00000001    // 16
    , 0b00000010    // 17
    , 0b00000100    // 18
    , 0b00001000    // 19
    , 0b00010000    // 20
    , 0b00100000    // 21
    , 0b01000000    // 22
    , 0b10000000    // 23

    , 0b00000000    // 24       flash and change register set
    
    , 0b00000001    // 25
    , 0b00000010    // 26
    , 0b00000100    // 27
    , 0b00001000    // 28
    , 0b00010000    // 29
    , 0b00100000    // 30
    , 0b01000000    // 31
};

void flash(int dms)
{
    digitalWrite(pinFLASH, FLASH_ON);
    delay(dms);
    digitalWrite(pinFLASH, FLASH_OFF);
}

void shift(uint8_t const data, uint8_t const rindex)
{
    // shiftOut(uint8_t dataPin, uint8_t clockPin, uint8_t bitOrder, byte value)

    const uint8_t   pinDATA[]   = { pinDATA0 , pinDATA1  };
    const uint8_t   pinCLOCK[]  = { pinCLOCK0, pinCLOCK1 };

    shiftOut(pinDATA[rindex], pinCLOCK[rindex], LSBFIRST, data);
    delay(dmsLIT);
    
    if ( 0 == data )
    {
        flash(dmsLIT);
    }
}

void loop()
{
    uint8_t rindex = 0;
    
    for ( size_t i = 0; i < sizeof(lookup); i++ )
    {
        uint8_t     data = lookup[i];
        shift(data, rindex);

        if ( 0 == data )
        {
            rindex = ((++rindex) & 1);
        }
    }
}

void setup()
{
    pinMode(pinCLOCK0, OUTPUT);
    pinMode(pinDATA0 , OUTPUT);
    pinMode(pinCLOCK1, OUTPUT);
    pinMode(pinDATA1, OUTPUT);
    pinMode(pinFLASH, OUTPUT);
}
10

a must buy book BTW

Ah the "KnR" book, an oldy but a goody. My Bible a long time ago.

Rob