Arduino的字符串连接Serial.println（）不工作

Question

我想首先发送整个文本到认定其长度和使用AT + CIPSEND = 长度的函数读取一些文本服务器的通数据来这里稍后打开TCP端口。在我的响应数据中添加一些额外的信息之前，一切正常。 我怀疑的字符限制，但无法找到一个理由，即使调试几个小时。

Serial.println（）不显示任何输出，因为它似乎字符串连接是不健康的。问题是文本没有被传递，因此CIPSEND不起作用。相应的代码部分及其输出如下所示。

void sendHTTPResponse(int connectionId, String content) { 
    Serial.println("SENDHTTPRESPONSE1: " + content); 

    // build HTTP response 
    String httpResponse; 
    String httpHeader; 
    // HTTP Header 
    httpHeader = "HTTP/1.1 200 OK\r\nContent-Type: text/html; charset=UTF-8\r\n"; 
    httpHeader += "Content-Length: "; 
    httpHeader += content.length(); 
    httpHeader += "\r\n"; 
    httpHeader += "Connection: close\r\n\r\n"; 
    Serial.println("SENDHTTPRESPONSE2: " + httpHeader); 
    httpResponse = httpHeader + content + " "; // There is a bug in this code: the last character of "content" is not sent, I cheated by adding this extra space 
    Serial.println("HTTPRESPONSE3: " + httpResponse); 
    sendCIPData(connectionId, httpResponse); 
} 

和串行监视器输出。 HTTPRESPONSE3似乎在某种程度上是空的？

SENDHTTPRESPONSE1: {"data":[{"id":"100"}]}{"data":[{"id":"100"}]}{"data":[{"id":"100"}]}{"data":[{"id":"100"}]} 
SENDHTTPRESPONSE2: HTTP/1.1 200 OK 
Content-Type: text/html; charset=UTF-8 
Content-Length: 92 
Connection: close 



DATA LENGTH: 



====================================================== 
Executing command: AT+CIPSEND=0,0 


HTTP/1.1 
CoAT+CIPSEND=0,0 

在此先感谢。

Answer 1

这个答案并不真正解决您的问题。 为了我的借口，我没有Arduino的和我在一起，所以我无法重现您的问题。 :)

不过，既然你都成“字符串连接”的风格，我想你可能使用这里发布的源代码中获益（前提是你的项目有空间的话）。

这是一个小C++ - 风格包装围绕打印库，我两年前写的。它可以让你写这样的东西：

io::cout << "This is a beautiful message!\n" 
     << io::setprecision(3) << some_float << "\n" 
     << io::setbase(BIN) << some_int << io::endl; 

默认情况下，库提供io::cout它通过平常Serial打印。您可以将该库与任何实现打印界面的对象挂钩，例如串行和软件序列。

与您现在正在做的不同之处在于，通过使用“< <”，您将获得与“+”相同的干净的代码样式，但不需要创建临时String。所有东西都会立即下达到输出缓冲区以打印出来。因此，您不应该遇到与您现在正在经历的相同问题。换句话说，这就是@Olaf在评论中提出的建议，但以一种奇特的方式。 ;）

注意：你可能需要修复包括在测试iocout.ino文件，以适应您的项目。

---

• cout.h

  #ifndef __COUT_H__ 
  #define __COUT_H__ 
  
  #include <Arduino.h> 
  
  namespace io { 
  
  /** 
  * marker to end a message 
  * (prints newline) 
  */ 
  struct Endl {}; 
  const Endl endl = Endl(); 
  
  /** 
  * marker to modify way in which numbers are 
  * printed on output stream 
  */ 
  struct setbase { 
      uint8_t base; 
      setbase(uint8_t v = DEC): base(v) {} 
  }; 
  
  /** 
  * marker to modify number of digits of doubles 
  * printed on output stream 
  */ 
  struct setprecision { 
      uint8_t precision; 
      setprecision(uint8_t v = 2): precision(v) {} 
  }; 
  
  
  /** 
  * class out 
  * 
  * Provides a C++-like interface for printing stuff on 
  * an output Stream, e.g. Serial, SoftwareSerial objects 
  * Assumes a separated Stream initialization handling 
  */ 
  class out { 
  public: 
  
      out(Print& print = Serial, uint8_t fmt = DEC, uint8_t dgt = 2); 
      out(const out& other); 
      out& operator =(const out& other); 
      virtual ~out(); 
  
      inline out& operator<<(const String& msg) 
      { 
       __print.print(msg); 
       return *this; 
      }; 
  
      inline out& operator<<(const char msg[]) 
      { 
       __print.print(msg); 
       return *this; 
      }; 
  
      inline out& operator<<(char c) 
      { 
       __print.print(c); 
       return *this; 
      }; 
  
      inline out& operator<<(unsigned char uc) 
      { 
       __print.print(uc, __base); 
       return *this; 
      }; 
  
      inline out& operator<<(int n) 
      { 
       __print.print(n, __base); 
       return *this; 
      }; 
  
      inline out& operator<<(unsigned int un) 
      { 
       __print.print(un, __base); 
       return *this; 
      }; 
  
      inline out& operator<<(long l) 
      { 
       __print.print(l, __base); 
       return *this; 
      }; 
  
      inline out& operator<<(unsigned long ul) 
      { 
       __print.print(ul, __base); 
       return *this; 
      }; 
  
      inline out& operator<<(double d) 
      { 
       __print.print(d, __precision); 
       return *this; 
      }; 
  
      inline out& operator<<(const __FlashStringHelper *fsh) 
      { 
       __print.print(fsh); 
       return *this; 
      }; 
  
      inline out& operator<<(const Printable& pr) 
      { 
       __print.print(pr); 
       return *this; 
      }; 
  
      inline out& operator<<(const Endl& el) 
      { 
       __print.println(""); 
       __base = DEC; 
       __precision = 2; 
       return *this; 
      }; 
  
      inline out& operator<<(const setbase& p) 
      { 
       __base = p.base; 
       return *this; 
      }; 
  
      inline out& operator<<(const setprecision& p) 
      { 
       __precision = p.precision; 
       return *this; 
      }; 
  
      inline int getWriteError() 
      { 
       return __print.getWriteError(); 
      }; 
  
      inline void clearWriteError() 
      { 
       __print.clearWriteError(); 
      }; 
  
  private: 
      Print& __print; 
      ///< output stream, must be separately initalized 
      uint8_t __base; 
      ///< base with which print numerical data 
      uint8_t __precision; 
      ///< number of fractional digits of float/double values 
  }; 
  
  /** 
  * Global io::cout object 
  */ 
  extern out cout; 
  
  } /* namespace io */ 
  
  #endif 
  

• COUT。CPP

  #include "cout.h" 
  
  namespace io { 
  
  out cout; 
  
  out::out(Print& print, uint8_t fmt, uint8_t dgt): 
      __print(print), __base(fmt), 
      __precision(dgt) 
  { 
      // nothing to do 
  }; 
  
  out::out(const out& other): 
      __print(other.__print), 
      __base(other.__base), 
      __precision(other.__precision) 
  { 
      // nothing to do 
  }; 
  
  out& out::operator =(const out& other) 
  { 
      if (this != &other) { 
       __print = other.__print; 
       __base = other.__base; 
       __precision = other.__precision; 
      } 
      return *this; 
  }; 
  
  out::~out() 
  { 
      // nothing to do 
  }; 
  
  } /* namespace io */ 
  

• 测试iocout.ino

  #include <Arduino.h> 
  #include "src/cout.h" 
  
  /******************************************************************************/ 
  /*** PINS & GLOBALS               ***/ 
  /******************************************************************************/ 
  
  const uint32_t SERIAL_BAUDRATE = 4800; 
  
  /******************************************************************************/ 
  /*** RESOURCES                ***/ 
  /******************************************************************************/ 
  
  /******************************************************************************/ 
  /*** MAIN                 ***/ 
  /******************************************************************************/ 
  
  /** 
  * setup: 
  * sets up the resources used within the arduino 
  */ 
  void setup() 
  { 
      /* Initialize serial */ 
      Serial.begin(SERIAL_BAUDRATE); 
      while (!Serial) 
      { 
       /* Needed by Arduino Leonardo */ 
      } 
  
      /* new c++-like access to serial! */ 
      io::cout << "##### Arduino Station #####\n\n" 
        << "- io::cout test 1.0" << io::endl; 
  } 
  
  /** 
  * loop: 
  * 
  */ 
  void loop() 
  { 
      /* compute deltaTime */ 
      uint32_t curr_time = millis(); 
      static uint32_t start_time = curr_time; // note: initialized once! 
      uint32_t deltaTime = curr_time - start_time; 
      start_time = curr_time; 
  
      io::cout << "\n> Last loop duration was: "; 
  
      io::cout << io::setprecision(3) 
        << deltaTime/1000.0f 
        << " s." << io::endl; 
  
      io::cout << "> 1025 in binary is: " 
        << io::setbase(BIN) 
        << 1025 << io::endl; 
  
      delay(10000); 
  }