Arduino 字节转 HEX (12Bit)

Question

I am learning Arduino. Now I want to change the color of the background.

I am using the Uno Board, and the Sparkfun Color LCD Shield. I am also using the SparkFunColorLCDShield Library.

The easiest way the change the color is to do lcd.clean(HEXCODE); Example for white background: lcd.clean(0xFFF); (12Bit of 0xFFFFFF) It's also working with lcd.clean(16777215);

The 16777215 is the decimal number of 0xFFFFFF. Now I need a method, that gives me the decimal number of any HEX Number.

More examples:

• 00FFFFF -> 1048575
• 000FFFF -> 65535

Answer 1

After much guessing and reading here :

Maybe you want this:

#include <stdlib.h>
#include <stdio.h>


int Convert24bitColorStringTo12BitColor(const char *colorcode24)
{
  long color24 = strtol(colorcode24, NULL, 16);
  long color12 = ((color24 & 0xf0) >> 4) | ((color24 & 0xf000) >> 8) | ((color24 & 0xf00000) >> 12);
  return color12;
}

int main()
{
  printf("%x\n", Convert24bitColorStringTo12BitColor("abcdef"));
  printf("%x\n", Convert24bitColorStringTo12BitColor("ffff"));
}

This prints:

ace
ff