strcpy( str_buffer, dec2ascii( read_hour() ) ); //read_hour() returns 12 in dec (tested)
strcat( str_buffer, ":"                      ); 
strcat( str_buffer, dec2ascii( read_min()  ) ); //dec2ascii() returns ptr to "34"
strcat( str_buffer, ":"                      );
strcat( str_buffer, dec2ascii( read_sec()  ) );

LCD_sendstring( str_buffer );