Arduino + ESP8266, How can i send Continous Get Request? - tcp

Question

I have a code that was available on this website https://hackaday.io/project/3072/instructions . I made the code work by modifying it a little but the main problem is that it serves the GET request only once. What i want is continuous page fetch and there should be no TCP connection closing.
I have tried different methods but the connection always breaks after 1 GET request.
Moreover, if i do not send any GET request then it serves the domain's index page continuously without breaking TCP connection.
This is the original code http://dunarbin.com/esp8266/retroBrowser.ino.
And this is mine.
#define SSID "vivek"
#define PASS "bustedparamour21"
#define DEST_HOST "www.electronics2work.com"
#define DEST_IP "31.170.161.234"
#define TIMEOUT 10000 // mS
#define CONTINUE false
#define HALT true
#define ECHO_COMMANDS // Un-comment to echo AT+ commands to serial monitor
// Print error message and loop stop.
void errorHalt(String msg)
{
Serial.println(msg);
Serial.println("HALT");
while(true){};
}
// Read characters from WiFi module and echo to serial until keyword occurs or timeout.
boolean echoFind(String keyword)
{
byte current_char = 0;
byte keyword_length = keyword.length();
// Fail if the target string has not been sent by deadline.
long deadline = millis() + TIMEOUT;
while(millis() < deadline)
{
if (Serial1.available())
{
char ch = Serial1.read();
Serial.write(ch);
if (ch == keyword[current_char])
if (++current_char == keyword_length)
{
Serial.println();
return true;
}
}
}
return false; // Timed out
}
// Read and echo all available module output.
// (Used when we're indifferent to "OK" vs. "no change" responses or to get around firmware bugs.)
void echoFlush()
{while(Serial1.available()) Serial.write(Serial1.read());}
// Echo module output until 3 newlines encountered.
// (Used when we're indifferent to "OK" vs. "no change" responses.)
void echoSkip()
{
echoFind("\n"); // Search for nl at end of command echo
echoFind("\n"); // Search for 2nd nl at end of response.
echoFind("\n"); // Search for 3rd nl at end of blank line.
}
// Send a command to the module and wait for acknowledgement string
// (or flush module output if no ack specified).
// Echoes all data received to the serial monitor.
boolean echoCommand(String cmd, String ack, boolean halt_on_fail)
{
Serial1.println(cmd);
#ifdef ECHO_COMMANDS
Serial.print("--"); Serial.println(cmd);
#endif
// If no ack response specified, skip all available module output.
if (ack == "")
echoSkip();
else
// Otherwise wait for ack.
if (!echoFind(ack)) // timed out waiting for ack string
if (halt_on_fail)
errorHalt(cmd+" failed");// Critical failure halt.
else
return false; // Let the caller handle it.
return true; // ack blank or ack found
}
// Connect to the specified wireless network.
boolean connectWiFi()
{
String cmd = "AT+CWJAP=\""; cmd += SSID; cmd += "\",\""; cmd += PASS; cmd += "\"";
if (echoCommand(cmd, "OK", CONTINUE)) // Join Access Point
{
Serial.println("Connected to WiFi.");
return true;
}
else
{
Serial.println("Connection to WiFi failed.");
return false;
}
}
// ******** SETUP ********
void setup()
{
Serial.begin(9600); // Communication with PC monitor via USB
Serial1.begin(9600); // Communication with ESP8266 via 5V/3.3V level shifter
Serial1.setTimeout(TIMEOUT);
Serial.println("ESP8266 Demo");
delay(2000);
Serial.println("Module is ready.");
echoCommand("AT+GMR", "OK", CONTINUE); // Retrieves the firmware ID (version number) of the module.
echoCommand("AT+CWMODE?","OK", CONTINUE);// Get module access mode.
// echoCommand("AT+CWLAP", "OK", CONTINUE); // List available access points - DOESN't WORK FOR ME
echoCommand("AT+CWMODE=1", "", HALT); // Station mode
echoCommand("AT+CIPMUX=1", "", HALT); // Allow multiple connections (we'll only use the first).
//connect to the wifi
boolean connection_established = false;
for(int i=0;i<5;i++)
{
if(connectWiFi())
{
connection_established = true;
break;
}
}
if (!connection_established) errorHalt("Connection failed");
delay(5000);
//echoCommand("AT+CWSAP=?", "OK", CONTINUE); // Test connection
echoCommand("AT+CIFSR", "", HALT); // Echo IP address. (Firmware bug - should return "OK".)
//echoCommand("AT+CIPMUX=0", "", HALT); // Set single connection mode
}
// ******** LOOP ********
void loop()
{
// Establish TCP connection
String cmd = "AT+CIPSTART=0,\"TCP\",\""; cmd += DEST_IP; cmd += "\",80";
if (!echoCommand(cmd, "OK", CONTINUE)) return;
delay(2000);
// Get connection status
if (!echoCommand("AT+CIPSTATUS", "OK", CONTINUE))
return;
// Build HTTP request.
cmd = "GET /";
cmd +="iot/graphing.php?a=1&b=ldr&c=41 ";
cmd += "HTTP/1.1\r\nHost: ";
cmd += DEST_HOST;
cmd += ":80\r\n\r\n";
// Ready the module to receive raw data
if (!echoCommand("AT+CIPSEND=0,"+String(cmd.length()), ">", CONTINUE))
{
echoCommand("AT+CIPCLOSE", "", CONTINUE);
Serial.println("Connection timeout.");
return;
}
// Send the raw HTTP request
echoCommand(cmd, "OK",CONTINUE ); // GET
// Loop forever echoing data received from destination server.
while(true)
while (Serial1.available())
Serial.write(Serial1.read());
errorHalt("ONCE ONLY");
}
This code makes get request only once. How can i make it serve GET request Continously without closing TCP connection?
THANKS in Advance!!

Answer 1

You need to close your connection using AT+CIPCLOSE and then start a new connection again.
For example, if you need to make two connections everytime(like making connection with 2 websites) , you can make 1 connection, then close this connection. Now make another connection and close it.
I made 2 connections in my loop() function using above logic and it is working fine.