# 2. 串口

BiBoard有2个串口，分别位于2个2个扩展插座（P16，P17）上。 

P16上的串口1同时连接着USB下载器，请勿同时使用下载器和外接串口设备，会因为串口电压分压而导致通讯错误。 

在Arduino例程中，串口0为Serial，串口1为Serial1。将Serial和Serial1的数据互相转发。

```
/* In this demo, we use Serial and Serial1 
*  Serial and Serial1 send to each other 
*/

void setup() {
  // initialize both serial ports:
  Serial.begin(115200);
  Serial1.begin(115200);
}

void loop() {
  // read from port 1, send to port 0:
  if (Serial1.available()) {
    int inByte = Serial1.read();
    Serial.write(inByte);
  }

  // read from port 0, send to port 1:
  if (Serial.available()) {
    int inByte = Serial.read();
    Serial1.write(inByte);
  }
}
```


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