字节的位操作

#define lowByte(word) ((uint8_t)(word))
#define highByte(word) ((uint8_t)((word) >> 8))
#define bitRead(val, bit) (((val) >> (bit)) & 0x01)
#define bitSet(val, bit) ((val) |= (1 << (bit)))
#define bitClear(val, bit) ((val) &= ~(1 << (bit)))
#define bitFlip(val, bit) ((val) ^= (1 << (bit)))