Get a number wich its binary form is the number of a char array

Projects Programming
1

To use some shift register, I need to give them a number in wich every bit means on/off in that output pin of the ICs. To do that, I wrote a program that should turn on the selected pins adding a 1 or a 0 to a char, and then convert int to the number I want:

void send(int column, int layer) {
  
  // Creates the binary number to send from the given column and layer values
  static char data[sizeof(columns) + sizeof(layers];

  for (int i = 0; i < sizeof(data); i++) {

    if (i == columns[column] or i == layers[layer]) {

      strcat(data, "1");

    } else {

      strcat(data, "0");

    }

  }  
  
  /**** HELP ****/
  
  // Sends the data
  digitalWrite(LATCH_PIN, LOW); // Starts the transmission
  shiftOut(DATA_PIN, CLOCK_PIN, LSBFIRST, data); // Sends the data of the fourth IC
  shiftOut(DATA_PIN, CLOCK_PIN, LSBFIRST, data >> 8); 
  shiftOut(DATA_PIN, CLOCK_PIN, LSBFIRST, data >> 16);
  shiftOut(DATA_PIN, CLOCK_PIN, LSBFIRST, data >> 24); // Sends the data of the first IC
  digitalWrite(LATCH_PIN, HIGH); // Ends the transmission

}

In the part where is written HELP is the problem, because I don't know how to convert this char array to a number that can be read by the IC. I think I could someway convert the data array to a number, but would be a 30 digit number, and then I should rewrite it as another int in winch its binary form is the same than the decimal of the very large number before.

Can I have some help?

2

You certainly don't want to use character arrays and ASCII representations of the digits "1" or "0" for this.

Just set the bits you need directly in the integer array element.

Tell us more about the shift register (post a link to the data sheet) for more detailed advice.

3

If I understand your question correctly, you want binary bit manipulation. For instance

unsigned int myBits = 0;

To set bit 0 use bitwise OR (single | operator)

myBits = myBits | 0x1;

To set any other bit, just use a bit (0x1) and shift it to the left before using OR to set the specific bit

myBits = myBits | ( 0x1 << 5 );

You can do this with multiple bits. You can delete bits with bitwise AND (& operator). All bits you do not want to delete need to be 0x1. Check out boolean logic.

4

To set bit N in an integer variable, I use

x = x | (1<<N); //or more compactly
x |= (1<<N);

To clear bit N of an integer variable, I use

x = x & (~(1<<N)); //or more compactly
x &= ~(1<<N);

This works correctly for N=0;

5

Or you can use the ready made macros

bit() 
bitClear() 
bitRead() 
bitSet() 
bitWrite() 
highByte() 
lowByte()

Have a look at the documentation for Bits and Bytes functions

6

Thank you! I'll search boolean logic and bit and byte functions, didn't know anything about that.

To everyone who want more information about my shift register, is a 74HC595n, an 8 bit shift register. The function shiftOut() sends a number. Each bit of the number represents a high (1) or low (0) voltage output of one of its pins, so I wanted a way to control this on/off in the number I send to animate the LED cube
I've built.

Greetings from Argentina!

7

You might want to read this as well