Tak už to vím:

Unfortunately, most C++ compilers do not have any means of expressing binary numbers directly in source code. A few allow the prefix 0b followed by a series of 0 and 1 digits, e.g. 0b11 == 3. The C++ compiler used by Arduino does not support this syntax. However, starting in Arduino 0007, the constants B0 through B11111111 are defined for your convenience.