[英]How to connect Arduino to C++ using sockets?
我的C ++客戶端套接字代碼僅收集Arduino套接字服務器提供的輸出的第一行（我想我可以這樣稱呼）。 您能告訴我我的C ++代碼在哪里出問題以及如何解決嗎？ 如果問題太冗長，請跳至底部的C ++代碼。
硬件設置 ：帶有以太網卡（屏蔽）的Arduino Mega和帶Ubuntu 16.04的英特爾NUC。 使用電纜和非管理型交換機連接兩個設備。
Arduino Side ：我從Arduino以太網庫中的Web服務器示例開始，然后修改了代碼，直到能夠收集所有I / O的狀態，處理I / O數據並將結果提供給Web客戶端。 下圖顯示了我的Arduino提供的HTML的快照。
處理事物的套接字服務器端的Arduino代碼如下（一切正常，但認為包括在內可以顯示所有內容）：
#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");
}
}
英特爾NUC與Ubuntu 16.04和C ++ 11 ：我一直在關注一個教程（ https://www.binarytides.com/socket-programming-c-linux-tutorial/ ）來找出套接字客戶端，並學習C ++來自https://www.learncpp.com 。 到目前為止，我已經能夠向Google服務器發送請求，並使用套接字收集HTML頁面，然后將HTML打印到終端：
這是我的C ++代碼：
#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;
}
問題 ：當我在C ++程序中將IP地址從Google更改為Arduino時，cpp客戶端套接字程序僅收集Arduino套接字服務器輸出的第一行。 我知道這是第一行，因為我通過添加“ ..但沒關系”修改了Arduino服務器的第一行，並且更改顯示在c ++程序的標准輸出窗口中。 我需要C ++程序來收集整個輸出，而不僅僅是第一行。 對於我的一生，我不知道怎么做。
您能幫我解決以下問題：
我為“ fix-my-codez”問題事先表示歉意，但是我讀過的所有問題對我來說都太高級了，因為它們解決了緩沖區溢出，安全性，字節序問題，錯誤處理，格式錯誤的消息等。遠遠超出了我的需求（能力可能更准確）。 非常感謝您的時間和幫助。
非常感謝Jonathan Potter和Remy Lebeau在評論中提供了有效的答案。 我執行了您的建議/答案，一切正常。 我沒有觸摸Arduino代碼，而是在CPP代碼中進行了以下更改：
在問題中的CPP代碼中，從char buffer [20000] = {};刪除所有內容（包括其中） char buffer [20000] = {}; 並替換為：
//***********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;
這些變化（我確信可以從這里到月球和從月球來回批評）使我能夠獲取arduino發送的數據而不會丟失單個ASCII字符。 謝謝！
另外，感謝David Schwartz和Remy Lebeau指出我使用的HTTP協議非常糟糕。 我使用HTTP，因為我知道這是Arduino代碼中的一個有效示例。 現在的目標是刪除HTML，並找到一種更有效的方法（僅使用套接字）將值傳遞給cpp代碼。 非常感謝您的評論！
****編輯****
好的，因此，如果您仍在閱讀本文，則必須使用以太網將一些信息從Arduino傳遞到cpp程序。 如果是這樣，請繼續閱讀。 在指導我如何接收完整的Arduino響應之后，我刪除了所有HTML和HTTP，並通過字母填充（例如：Aint1B，Cint2D，Efloat1F等）從Arduino發送了我需要的值。 我用~~~字符標記了Arduino的傳輸結束。 涼。 但是，由於某種原因，有時我會得到整個Arduino響應，有時它會丟失一些消息尾部。 這是我學到的：
\\n字符全部都是recv提取的！ 考慮到此行為，我修改了cpp代碼。 該代碼接收到整個消息，並且當它收到時，將停止recv方法的其他不必要的循環。 希望你覺得它有用：
//***********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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