How to parse string like "FF33BB" to 3 bytes ? ..for LEDStripe

[StefanWxx 2]

Hi,

 

in my code i want so set the color for a rgb led stripe. I use the WS2811Driver library.

 

I tried this but it doesn't work:

// blink_strip - ws2811 led strip blink example
// 11-15-2012 Initial Version 0.1

#include <WS2811Driver.h>
byte leds0[30];
byte leds1[30];


// 24 bits of color data stored GGRRBB
//const uint8_t leds0[] = { 0x00,0xff,0x00, 0xff,0x00,0x00, 0x00,0x00,0xff, 0xff,0xff,0xff }; // R,G,B,W
//const uint8_t leds1[] = { 0x00,0x00,0x00, 0x00,0x00,0x00, 0x00,0x00,0x00, 0x00,0x00,0x00 }; // 0,0,0,0,

WS2811Driver ledStrip; // uses P1_7 as datapin connect to DIN on strip

void setup(void)
{
    ledStrip.setLEDCount(10); // setup for 4 leds on a strip
    ledStrip.begin();        // configure P1.7 for output
}

void loop() {
    //ledStrip.write(leds0);               // set leds to red,green,blue,white
    //delay(500);
    //ledStrip.write(leds1,sizeof(leds1)); // turn off all 4 leds
    //delay(500);
    String color = "0000FF";
    
    for(byte x = 0; x < 30 ; x++){
      leds0[x] = byte('F');
      //leds0[x+1] = byte(color.substring(2,3));
      //leds0[x+2] = byte(color.substring(4,5));
      }  
    ledStrip.write(leds0); 
    delay(5000);
    for(byte x = 0; x < 30 ; x++){
      leds1[x] = 0x00;
      //leds0[x+1] = byte(color.substring(2,3));
      //leds0[x+2] = byte(color.substring(4,5));
      }  
     ledStrip.write(leds1); 
     delay(5000);
}

How can I convert the string to 3 bytes?

 

 

[roadrunner84 466]

#include <cstdlib>

 

const char* s = "ff33bb";

unsigned long a = strtoul (s, NULL, 16);

// a is equal to 0xff33bb is equal to 996283

 

// to break the 32-bit integer into three separate 8-bit integers

unsigned char b[3];

b[0] = (a >> 16) & 0xFF;

b[1] = (a >> 8) & 0xFF;

b[2] = a & 0xFF;

// b[0] is equal to 0xff is equal to 255

// b[1] is equal to 0x33 is equal to 51

// b[2] is equal to 0xbb is equal to 187

 

[StefanWxx 2]

Okay,

just another Question about this..

 

How can ich make this with a loop:

void loop() {
    
    const char* color = "34acef";  //GGRRBB
    unsigned long a = strtoul (color, NULL, 16);
    
    

    // want to do this in a loop:   
    leds0[0] = (a >> 16) & 0xFF;
    leds0[1] = (a >> 8) & 0xFF;
    leds0[2] = a & 0xFF;
    
    leds0[3] = (a >> 16) & 0xFF;
    leds0[4] = (a >> 8) & 0xFF;
    leds0[5] = a & 0xFF;
    
    leds0[6] = (a >> 16) & 0xFF;
    leds0[7] = (a >> 8) & 0xFF;
    leds0[8] = a & 0xFF;
    
    leds0[9] = (a >> 16) & 0xFF;
    leds0[10] = (a >> 8) & 0xFF;
    leds0[11] = a & 0xFF;
    
    leds0[12] = (a >> 16) & 0xFF;
    leds0[13] = (a >> 8) & 0xFF;
    leds0[14] = a & 0xFF;
    
    leds0[15] = (a >> 16) & 0xFF;
    leds0[16] = (a >> 8) & 0xFF;
    leds0[17] = a & 0xFF;
    
   
   
      
      
    ledStrip.write(leds0); 
    
    delay(5000);
      
    
    
}

[yosh 121]

@@StefanWxx Something like:

for(int i=0;i<6;i++)
{
    leds0[i*3 + 0] = (a >> 16) & 0xFF;
    leds0[i*3 + 1] = (a >> 8) & 0xFF;
    leds0[i*3 + 2] = a & 0xFF;
}

[StefanWxx 2]

Thank you, it works beautifully :-)

[jpnorair 340]

Why don't you just use binary arrays instead?

 

Maybe something like this:

 

uint8_t array[3] = { 0x00, 0x11, 0x22 };