arduino串口是什么_arduino串口_arduino串口连接不上(2)

}

else

{

*_ucsra = 0;

baud_setting = (F_CPU / 8 / baud - 1) / 2;

}

// assign the baud_setting, a.k.a. ubbr (USART Baud Rate Register)

*_ubrrh = baud_setting >> 8;

*_ubrrl = baud_setting;

sbi(*_ucsrb, _rxen);

sbi(*_ucsrb, _txen);

sbi(*_ucsrb, _rxcie);

}

2. if (Serial.available())

该语句用来判断Arduino串口是否收到数据，函数Serial.available( )返回值为int型，不带参数。函数原型如下：

int HardwareSerial::available(void)

{

return (RX_BUFFER_SIZE + _rx_buffer->head - _rx_buffer->tail) % RX_BUFFER_SIZE;

}

3. brightness = Serial.read();

该语句的功能是将串口数据读入到变量brightness中，函数Serial.read( )也不带参数，返回值为串口数据，int型。arduino串口函数原型如下：

int HardwareSerial::read(void)

{

// if the head isnt ahead of the tail, we dont have any characters

if (_rx_buffer->head == _rx_buffer->tail)

{

return -1;

}

else

{

unsigned char c = _rx_buffer->buffer[_rx_buffer->tail];

_rx_buffer->tail=(_rx_buffer->tail + 1) % RX_BUFFER_SIZE;

return c;

}

}

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