I tried SIM808_TCPConnection example. But "Hello World!" did not return.

[burakkorman]

The code I wrote:

`#include <DFRobot_sim808.h>
#include <SoftwareSerial.h>

#define PIN_TX 10
#define PIN_RX 11
SoftwareSerial mySerial(PIN_TX,PIN_RX);
DFRobot_SIM808 sim808(&mySerial);//Connect RX,TX,PWR,

char http_cmd[] = "GET /media/uploads/mbed_official/hello.txt HTTP/1.0\r\n\r\n";
char buffer[512];

void setup(){
mySerial.begin(9600);
Serial.begin(9600);

//******** Initialize sim808 module *************
while(!sim808.init()) {
delay(1000);
Serial.print("Sim808 init error\r\n");
}
delay(3000);

//*********** Attempt DHCP *******************
while(!sim808.join(F("cmnet"))) {
Serial.println("Sim808 join network error");
delay(2000);
}

//************ Successful DHCP ****************
Serial.print("IP Address is ");
Serial.println(sim808.getIPAddress());

//*********** Establish a TCP connection ************
if(!sim808.connect(TCP,"mbed.org", 80)) {
Serial.println("Connect error");
}else{
Serial.println("Connect mbed.org success");
}

//*********** Send a GET request *****************
Serial.println("waiting to fetch...");
sim808.send(http_cmd, sizeof(http_cmd)-1);
while (true) {
int ret = sim808.recv(buffer, sizeof(buffer)-1);
if (ret <= 0){
Serial.println("fetch over...");
break;
}
buffer[ret] = '\0';
Serial.print("Recv: ");
Serial.print(ret);
Serial.print(" bytes: ");
Serial.println(buffer);
break;
}

//************* Close TCP or UDP connections **********
sim808.close();

//*** Disconnect wireless connection, Close Moving Scene *******
sim808.disconnect();
}

void loop(){

}`

But I get such a result :
`

[hoerup]

It doesn't seems that mbed.org likes HTTP 1.0 (which really shouldn't come as a surprise)
Try sending it as a http 1.1 request, and remember to send the host header

[burakkorman]

@hoerup I tried, but I get a 400 (Bad Request) error.

[hoerup]

Could you paste your updated code

[burakkorman]

` #include <DFRobot_sim808.h>
#include <SoftwareSerial.h>

#define PIN_TX 10
#define PIN_RX 11
SoftwareSerial mySerial(PIN_TX,PIN_RX);
DFRobot_SIM808 sim808(&mySerial);//Connect RX,TX,PWR,

char http_cmd[] = "GET /media/uploads/mbed_official/hello.txt HTTP/1.1\r\n\r\n";
char buffer2[512];

void setup(){
mySerial.begin(9600);
Serial.begin(9600);

//******** Initialize sim808 module *************
while(!sim808.init()) {
    delay(1000);
    Serial.print("Sim808 init error\r\n");
}
delay(3000);

//*********** Attempt DHCP *******************
while(!sim808.join(F("cmnet"))) {
    Serial.println("Sim808 join network error");
    delay(2000);
}

//************ Successful DHCP ****************
Serial.print("IP Address is ");
Serial.println(sim808.getIPAddress());

//*********** Establish a TCP connection ************
if(!sim808.connect(TCP,"mbed.org", 80)) {
    Serial.println("Connect error");
}else{
    Serial.println("Connect mbed.org success");
}

//*********** Send a GET request *****************
Serial.println("waiting to fetch...");
sim808.send(http_cmd, sizeof(http_cmd)-1);
while (true) {
    int ret = sim808.recv(buffer2, sizeof(buffer2)-1);
    if (ret <= 0){
        Serial.println("fetch over...");
        break;
    }
    buffer2[ret] = '\0';
    Serial.print("Recv: ");
    Serial.print(ret);
    Serial.println(" bytes: ");
    Serial.println(buffer2);
    break;
}

//************* Close TCP or UDP connections **********
sim808.close();

//*** Disconnect wireless connection, Close Moving Scene *******
sim808.disconnect();

}

void loop(){

}`

[hoerup]

in my previous comment i did write "remember to send the host header" which is a mandatory header in http 1.1

[burakkorman]

Can you share sample code with me?

[hoerup]

char http_cmd[] = "GET /media/uploads/mbed_official/hello.txt HTTP/1.1\r\nHost:mbed.org\r\n\r\n";

[Fonfon60]

I tried with the last comment and the result was:
AT
AT+CFUN=1
AT+CPIN?
AT+CSTT="sl2sfr","",""
AT+CIICR
AT+CIFSR
IP Address is 100.75.179.118
AT+CIPSTART="TCP","mbed.org",80
Connect mbed.org success
waiting to fetch...
AT+CIPSEND=70
GET /media/uploads/mbed_official/hello.txt HTTP/1.1
Host:mbed.org

�Recv: 442 bytes: HTTP/1.1 301 Moved Permanently
Date: Tue, 21 Dec 2021 12:16:41 GMT
Content-Type: text/html
Content-Length: 162
Connection: keep-alive
Location: https://mbed.org/media/uploads/mbed_official/hello.txt
Strict-Transport-Security: max-age=31536000; includeSubDomains; preload

<title>301 Moved Permanently</title>

301 Moved Permanently

---

nginx

AT+CIPSTATUS
AT+CIPSHUT

So do you have a solution, please?