与arduino的字符串连接

Question

我在 Arduino Fio 设备上有一个非常短的示例程序运行。该程序正在发送串行数据。连接的 Xbee 路由器设备正在接收此数据并将其发送到连接到我的笔记本电脑的 Xbee 协调器设备。该程序还从串口读取数据。我可以发送 1 或 0 来打开或关闭 Fio 设备的 LED。

通过从我笔记本上的终端发送 1 或 0 来打开或关闭 LED 效果很好。

但是当我尝试读取 Fio 设备发送的数据时，我得到了这个：

his direction works 
is direction works 
s direction works 
 direction works 
direction works 
irection works 
rection works 
ection works 
ction works

...等等。

但我需要一个字符串 ("This direction works " + counter++;)，如您在以下代码示例中所见。

这是简短的 Arduino 草图：

int incomingByte = 0;   // for incoming serial data
 int counter = 0;

void setup()
{
    Serial.begin(57600);
    pinMode(13,OUTPUT);

    // blink twice at startup
    digitalWrite(13, LOW);
    delay(1000);

    digitalWrite(13, HIGH); // first blink
    delay(50);
    digitalWrite(13, LOW);
    delay(200);
    digitalWrite(13, HIGH); // second blink
    delay(50);
    digitalWrite(13, LOW);
}

void loop()
{   
    // send data only when you receive data:
    if (Serial.available() > 0) 
    {
        // read the incoming byte:
        incomingByte = Serial.read();

        if(incomingByte == '0')
        {
            digitalWrite(13, LOW);
        }
        else if(incomingByte == '1')
        {
            digitalWrite(13, HIGH);
        }

        // say what you got:
        Serial.print("Fio received: ");
        Serial.write(incomingByte);  // Arduino 1.0 compatibility
        Serial.write(10);    // send a line feed/new line, ascii 10
    }
    else
    {
        String sendData = "This direction works " + counter++;
        Serial.println(sendData);       
        delay(1500);
    }   
}

我做错了什么？为什么我没有得到：

This direction works 0
This direction works 1
This direction works 2
This direction works 3

...等等？

Answer 1

正如@Elric 和@Olaf 在评论中提到的那样，不可能像我发布的代码那样做到这一点。

再次阅读文档后，我发现了一个 "explanation":

Caution: You should be careful about concatenating multiple variable types on the same line, as you may get unexpected results. For example:

int sensorValue = analogRead(A0); String stringOne = "Sensor value: "; String stringThree = stringOne + sensorValue;
Serial.println(stringThree);

results in "Sensor Value: 402" or whatever the analogRead() result is, but

int sensorValue = analogRead(A0); String stringThree = "Sensor value: " + sensorValue; Serial.println(stringThree);

gives unpredictable results because stringThree never got an initial value before you started concatenating different data types.

首先，您必须初始化 String 变量以将两个连接的字符串分配给它。

与arduino的字符串连接

String concatenation with arduino

arduino

serial-port

processing

xbee