[英]How to connect Arduino to C++ using sockets?
我的C ++客户端套接字代码仅收集Arduino套接字服务器提供的输出的第一行（我想我可以这样称呼）。 您能告诉我我的C ++代码在哪里出问题以及如何解决吗？ 如果问题太冗长，请跳至底部的C ++代码。
硬件设置 ：带有以太网卡（屏蔽）的Arduino Mega和带Ubuntu 16.04的英特尔NUC。 使用电缆和非管理型交换机连接两个设备。
Arduino Side ：我从Arduino以太网库中的Web服务器示例开始，然后修改了代码，直到能够收集所有I / O的状态，处理I / O数据并将结果提供给Web客户端。 下图显示了我的Arduino提供的HTML的快照。
处理事物的套接字服务器端的Arduino代码如下（一切正常，但认为包括在内可以显示所有内容）：
#include <SPI.h>
#include <Ethernet.h>
byte mac[] = {0xBA, 0xDA, 0x55, 0x12, 0x34, 0x56};
IPAddress ip(192, 168, 0, 21);
EthernetServer server(80);
void setup()
{
Ethernet.begin(mac, ip);
// Check for Ethernet hardware present
if (Ethernet.hardwareStatus() == EthernetNoHardware)
{
Serial.println("Ethernet shield was not found. Sorry, can't run without hardware.");
while (true)
{
delay(1); // do nothing, no point running without Ethernet hardware
}
}
if (Ethernet.linkStatus() == LinkOFF)
{
Serial.println("Ethernet cable is not connected.");
}
server.begin();
}
void loop()
{
//true when there is an incoming connection
if (client)
{
Serial.println("new client");
// an http request ends with a blank line
boolean currentLineIsBlank = true;
while (client.connected())
{
if (client.available())
{
//the next two lines print the client HTTP GET request to serial.
char c = client.read();
Serial.write(c);
// if you've gotten to the end of the line (received a newline
// character) and the line is blank, the http request has ended,
// so you can send a reply
if (c == '\n' && currentLineIsBlank)
{
// send a standard http response header
client.println("HTTP/1.1 200 OK");
client.println("Content-Type: text/html");
client.println("Connection: close");
client.println("Refresh: 1");
client.println();
client.println("<!DOCTYPE HTML>");
client.println("<html>");
//whole bunch of client.println("...."); to dish out a web page.
client.println("</html>");
break;
}
if (c == '\n')
{
// you're starting a new line
currentLineIsBlank = true;
} else if (c != '\r')
{
// you've gotten a character on the current line
currentLineIsBlank = false;
}
}
}
// give the web browser time to receive the data
//delay(1);
// close the connection:
client.stop();
Serial.println("client disconnected");
}
}
英特尔NUC与Ubuntu 16.04和C ++ 11 ：我一直在关注一个教程（ https://www.binarytides.com/socket-programming-c-linux-tutorial/ ）来找出套接字客户端，并学习C ++来自https://www.learncpp.com 。 到目前为止，我已经能够向Google服务器发送请求，并使用套接字收集HTML页面，然后将HTML打印到终端：
这是我的C ++代码：
#include <iostream> //for std::cout & std::endl
#include<arpa/inet.h> //inet_addr
#include<string.h> // for strlen
int main()
{
int my_socket = socket(AF_INET , SOCK_STREAM , 0);
//make sure the socket we got is OK
if (my_socket == -1)
{
std::cout << "problem creating a socket." << std::endl;
}
struct sockaddr_in connectionToServer;
connectionToServer.sin_addr.s_addr = inet_addr("172.217.2.99");//google IP
connectionToServer.sin_family = AF_INET; //type of IP addres. where AF_INET is IPv4
connectionToServer.sin_port = htons(80); //port is set via a method
if (connect(my_socket , (struct sockaddr *)&connectionToServer , sizeof(connectionToServer)) < 0)
{
std::cout << "connect error" << std::endl;
return 1;
}
std::cout << "Connected" << std::endl;
//send a request to get a page
char *message = "GET / HTTP/1.1\r\n\r\n";
if( send(my_socket , message , strlen(message) , 0) < 0)
{
std::cout << "Send failed" << std::endl;
return 1;
}
std::cout << "Data Sent\n" << std::endl;
char buffer [20000] = {};
if( recv(my_socket, buffer , sizeof(buffer) , 0) < 0)
{
std::cout << "recv failed" << std::endl;
}
for(int i=0; i<20000 ; i++)
{
std::cout<< buffer[i];
}
return 0;
}
问题 ：当我在C ++程序中将IP地址从Google更改为Arduino时，cpp客户端套接字程序仅收集Arduino套接字服务器输出的第一行。 我知道这是第一行，因为我通过添加“ ..但没关系”修改了Arduino服务器的第一行，并且更改显示在c ++程序的标准输出窗口中。 我需要C ++程序来收集整个输出，而不仅仅是第一行。 对于我的一生，我不知道怎么做。
您能帮我解决以下问题：
我为“ fix-my-codez”问题事先表示歉意，但是我读过的所有问题对我来说都太高级了，因为它们解决了缓冲区溢出，安全性，字节序问题，错误处理，格式错误的消息等。远远超出了我的需求（能力可能更准确）。 非常感谢您的时间和帮助。
非常感谢Jonathan Potter和Remy Lebeau在评论中提供了有效的答案。 我执行了您的建议/答案，一切正常。 我没有触摸Arduino代码，而是在CPP代码中进行了以下更改：
在问题中的CPP代码中，从char buffer [20000] = {};删除所有内容（包括其中） char buffer [20000] = {}; 并替换为：
//***********receive the results**************************
//initialize a string
std::string totalResults;
//create a temp array. This will hold a single line recieved from
//the arduino.
char tempBuffer [300] = {};
//the number of lines I want to recieve from the arduino
int magicNumber = 100;
//recieve the arduino response
for(int i = 0; i < magicNumber ; i++)
{
//call the recv method over and over as it gets a single arduino line with
//every iteration.
if( recv(my_socket, tempBuffer , sizeof(tempBuffer) , 0) < 0)
{
std::cout << "recv failed" << std::endl;
}
//write out the single line we recieved to a string (which grows on the fly)
for(int i = 0; i < 300; i++ )
{
totalResults = totalResults+tempBuffer[i];
//kill the loop the moment there is a null character. When i created the
//array i initialized it with NULL characters. so if I am seeing a null
//character it means that the data I recieved from the arduino has all been
//given to the string.
if(tempBuffer[i] == NULL)
{
break;
}
}
//empty array - see: https://stackoverflow.com/questions/632846/clearing-a-char-array-c
std::fill(&tempBuffer[0], &tempBuffer[300], 0);
}
//print the results to the standard output.
std::cout << totalResults << std::endl;
这些变化（我确信可以从这里到月球和从月球来回批评）使我能够获取arduino发送的数据而不会丢失单个ASCII字符。 谢谢！
另外，感谢David Schwartz和Remy Lebeau指出我使用的HTTP协议非常糟糕。 我使用HTTP，因为我知道这是Arduino代码中的一个有效示例。 现在的目标是删除HTML，并找到一种更有效的方法（仅使用套接字）将值传递给cpp代码。 非常感谢您的评论！
****编辑****
好的，因此，如果您仍在阅读本文，则必须使用以太网将一些信息从Arduino传递到cpp程序。 如果是这样，请继续阅读。 在指导我如何接收完整的Arduino响应之后，我删除了所有HTML和HTTP，并通过字母填充（例如：Aint1B，Cint2D，Efloat1F等）从Arduino发送了我需要的值。 我用~~~字符标记了Arduino的传输结束。 凉。 但是，由于某种原因，有时我会得到整个Arduino响应，有时它会丢失一些消息尾部。 这是我学到的：
\\n字符全部都是recv提取的！ 考虑到此行为，我修改了cpp代码。 该代码接收到整个消息，并且当它收到时，将停止recv方法的其他不必要的循环。 希望你觉得它有用：
//***********receive the results**************************
//initialize a string
std::string totalResults = "";
//create a temp array. This will hold a single line recieved from
//the arduino.
char tempBuffer [300] = {};
//the number of lines I want to receive from the Arduino. This is an unusual
//value for the following reasons (figured out via println):
//(1) sometimes the buffer where the recv method reads from has only one value.
// ex: letter A only (as per my,*ahem", "protocol".
//(2) sometimes the \n is all a recv fetches!
//(3) sometimes the buffer where the recv method reads has multiple values, so
// the recv fetches many items that get unpacked in the second loop. This is
// why sometimes we increase the value by only 1, but get WAY more values. I
// observed this behaviour to be non repeating. Sometimes it reads 5 values,
// and sometimes it reads only 3 values.
// At a value of 60 I am always getting the message, and run the recv command
// unnecesserily. For this reason I have implemented the "end transmission"
// characters (~~~), which allow me to kill the for loop once the full message is
// retrieved.
int numberOfTimesRecvRuns = 60;
//number of characters per line. do not reduce as it is needed to be this size to
// get the full insult if the protocol is not followed.
int arduinoNumberOfCharsPerLine = 50;
bool fullResponseRecieved = false;
//recieve the entire arduino response. The magic number is the number of times
// we call the recv method (which reads a line from the socket).
for(int i = 0; i < numberOfTimesRecvRuns; i++)
{
//call the recv method over and over as it gets a single arduino line with
//every iteration.
if( recv(my_socket, tempBuffer , sizeof(tempBuffer) , 0) < 0)
{
std::cout << "recv failed" << std::endl;
}
//write out the single line we recieved to a string (which grows on the fly). 300 because
//i dont believe I will have more than 300 characters per line.
for(int j = 0; j < arduinoNumberOfCharsPerLine; j++ )
{
totalResults = totalResults+tempBuffer[j];
std::cout << "i: " << j << " value recv read: " << tempBuffer[j]<< std::endl;
//kill the loop the moment there is a null character. When i created the
//array i initialized it with NULL characters. so if I am seeing a null
//character it means that the data I recieved from the arduino has all been
//given to the string.
if(tempBuffer[j] == NULL )
{
std::cout << "I ran... See ya" << std::endl;
break;
}
//end of transmission detected
if(tempBuffer[j] == '~')
{
fullResponseRecieved = true;
}
}
//empty array - see: https://stackoverflow.com/questions/632846/clearing-a-char-array-c
std::fill(&tempBuffer[0], &tempBuffer[300], 0);
// A '~' character means the full message has been recieved and there is no
// need to keep looping for the purpose of running the recv method.
if(fullResponseRecieved == true)
{
//reset the value
fullResponseRecieved = false;
std::cout << "killing recv loop" << std::endl;
break;
}
}
//print the results to the standard output.
std::cout << totalResults << std::endl;
return 0;
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