controlling the speed/rate with a shift register outs(kinda Larson scanner)

Using Arduino LEDs and Multiplexing
1

Picking your brains and experience so i can apply to something i need.
I need to control a VCO using a shift register( lets say a 595).
On the outputs i can control the voltage with a resistive ladder(R2R),DAC style, so in that sense no doubts.
My doubt is this: Would the code below be the best way to have a control of its speed/rate ?! Is there a better, with better response way to do that ?! If so, can you lead me onto the right path, please ?!
Im developing a sound effects box, and despite already having achieved what id set myself to, id love to add more extras, and having a better control over it would be just brilliant to what i need .

  //Pin connected to ST_CP of stop
int latchPin = 8;
//Pin connected to SH_CP of stop
int clockPin = 12;
//Pin connected to DS of stop
int dataPin = 11;
int delayInput = 0;
int outDelay =0;

// Out to 74HC595 (Serial TO Parallel OUT)

void stopout(int numberToDisplay)
{
  // take the latchPin low so
  // the LEDs don't change while you're sending in bits:
  // digitalWrite(latchPin, LOW);
  // shift out the bits:
  shiftOut(dataPin, clockPin, MSBFIRST, numberToDisplay);

  //take the latch pin high so the LEDs will light up:
  digitalWrite(latchPin, LOW);
  digitalWrite(latchPin, HIGH);
}

void setup() {
  //set pins to output so you can control the shift register
  pinMode(latchPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(dataPin, OUTPUT);
  pinMode(delayInput, INPUT);
  //Lets Clear the LEDs - just incase the 74HC595 'remembers' its last state after restart.
  stopout(B00000000);
  delay(500);
}

void loop() {
  outDelay = analogRead (delayInput);
  stopout(B10000000);
  delay(outDelay);
  stopout(B01000000);
  delay(outDelay);
  stopout(B00100000);
  delay(outDelay);
  stopout(B00010000);
  delay(outDelay);
  stopout(B00001000);
  delay(outDelay);
  stopout(B00000100);
  delay(outDelay);
  stopout(B00000010);
  delay(outDelay);
  stopout(B00000001);
  delay(outDelay);
  stopout(B00000010);
  delay(outDelay);
  stopout(B00000100);
  delay(outDelay);
  stopout(B00001000);
  delay(outDelay);
  stopout(B00010000);
  delay(outDelay);
  stopout(B00100000);
  delay(outDelay);
  stopout(B01000000);
}
2

Njay was kind enough to note a nice way of doing it !

/*este e um caso basico para que possa perceber facilmente qualquer implementacao.
*Pino conectado ao ST_CP do stop*/
int latchPin = 8;
//Pino conectado ao SH_CP of stop
int clockPin = 12;
//Pino conectado ao DS do stop
int dataPin = 11;
int delayInput = 0;//pin para entrada analogica, neste caso um potenciometro
int outDelay =0;//O valor que vamos usar para converter  a leitura do pin analogico 
                //do pot para usar como valor de delay entre accoes

// Saida para 74HC595 (Serial TO Parallel OUT)

void stopout(int numberToDisplay)
{
  // baixar o latchPin para low para que
  // os LEDs nao mudem enquanto os bits sao enviados:
  // digitalWrite(latchPin, LOW);
  // passar os bits:
  shiftOut(dataPin, clockPin, MSBFIRST, numberToDisplay);

  //mudar o latch pin para HIGH para que os leds acendam:
  digitalWrite(latchPin, LOW);
  digitalWrite(latchPin, HIGH);
}

void setup() {
  //Configurar os pins para saida, para poder controlar o shift register 
  pinMode(latchPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(dataPin, OUTPUT);
  pinMode(delayInput, INPUT);//Atribuir o pin a entrada analogicado potenciometro
  //Apagar qualquer memoria que o 74HC595 possa ter da ultima configuracao dos pins 
  stopout(B00000000);
  delay(500);
}


void loop ()
{
    outDelay = analogRead (delayInput);
    for (unsigned char ctr = 0, mask = 0x80; ctr < 14; ctr++)
    {
        stopout(mask);
        delay(outDelay);
        mask = (ctr < 7? mask >> 1: mask << 1);
    }
}
3

Hello all,

I love the simplicity of this code. However being a noob I have to ask:

 mask = (ctr < 7? mask >> 1: mask << 1);

can some one break this down for me?

Is it a short code for if...then...else?

thank you

4

chengmania:
Is it a short code for if...then...else?

Yes, but it's not something you should try to emulate/use...

(it causes code readability problems like the one you're experiencing right now)

5

Is it a short code for if...then...else?

Yes. It controls the direction of flow for the leds based on the value of ctr.