unsigned char getLowbits(unsigned char){
  return x & 0x0F;
}

unsigned char getHighbits(unsigned char x){
  return (x & 0xF0)>>4;
}

unsigned char getBits(unsigned char x, unsigned char n){
  return (x >> n) & 0x01;
}
unsigned char clearBits(unsigned char x, unsigned char n){
  unsigned char clear = ~(1>>n);
  return clear & x;
}