Move code example to the examples repo

docs/tutorials/using_apis/connectivity/cellular_tcp.md

@@ -1,144 +1,20 @@
 ## Cellular TCP sockets
 
-This example opens a TCP socket with an echo server and performs a TCP transaction.
+Establishing a cellular connection to the network with Mbed OS only requires the following operations:
 
-```cpp TODO
-#include "mbed.h"
-#include "UDPSocket.h"
-#include "OnboardCellularInterface.h"
-
-// SIM pin code goes here
-#define PIN_CODE    "1234"
-
-// Network credentials like APN go here, e.g.,
-// "apn, username, password"
-#define CREDENTIALS "internet"
-
-// Number of retries /
-#define RETRY_COUNT 3
-
-// Cellular network interface object
+```
 OnboardCellularInterface iface;
 
-// Echo server hostname
-const char *host_name = "echo.u-blox.com";
-
-// Echo server TCP port
-const int port = 7;
-
-/**
- * Connects to the Cellular Network
- */
-nsapi_error_t do_connect()
-{
-    nsapi_error_t retcode;
-    uint8_t retry_counter = 0;
-
-    while (!iface.is_connected()) {
-
-        retcode = iface.connect();
-        if (retcode == NSAPI_ERROR_AUTH_FAILURE) {
-            printf("\n\nAuthentication Failure. Exiting application\n");
-            return retcode;
-        } else if (retcode != NSAPI_ERROR_OK) {
-            printf("\n\nCouldn't connect: %d, will retry\n", retcode);
-            retry_counter++;
-            continue;
-        } else if (retcode != NSAPI_ERROR_OK && retry_counter > RETRY_COUNT) {
-            printf("\n\nFatal connection failure: %d\n", retcode);
-            return retcode;
-        }
-
-        break;
-    }
-
-    printf("\n\nConnection Established.\n");
-
-    return NSAPI_ERROR_OK;
-}
-
-/**
- * Opens a TCP socket with the given echo server and undegoes an echo
- * transaction.
- */
-nsapi_error_t test_send_recv()
-{
-    nsapi_size_or_error_t retcode;
-
-    TCPSocket sock;
+/* Set Pin code for SIM card */
+iface.set_sim_pin(PIN_CODE);
 
-    retcode = sock.open(&iface);
-    if (retcode != NSAPI_ERROR_OK) {
-        printf("TCPSocket.open() fails, code: %d\n", retcode);
-        return -1;
-    }
+/* Set network credentials here, for example the APN */
+iface.set_credentials(CREDENTIALS);
 
-    SocketAddress sock_addr;
-    retcode = iface.gethostbyname(host_name, &sock_addr);
-    if (retcode != NSAPI_ERROR_OK) {
-        printf("Couldn't resolve remote host: %s, code: %d\n", host_name,
-               retcode);
-        return -1;
-    }
-
-    sock_addr.set_port(port);
-
-    sock.set_timeout(15000);
-    int n = 0;
-    char *echo_string = "TEST";
-    char recv_buf[4];
-
-    retcode = sock.connect(sock_addr);
-    if (retcode < 0) {
-        printf("TCPSocket.connect() fails, code: %d\n", retcode);
-        return -1;
-    } else {
-        printf("TCP: connected with %s server\n", host_name);
-    }
-    retcode = sock.send((void*) echo_string, sizeof(echo_string));
-    if (retcode < 0) {
-        printf("TCPSocket.send() fails, code: %d\n", retcode);
-        return -1;
-    } else {
-        printf("TCP: Sent %d Bytes to %s\n", retcode, host_name);
-    }
-
-    n = sock.recv((void*) recv_buf, sizeof(recv_buf));
-
-    sock.close();
-
-    if (n > 0) {
-        printf("Received from echo server %d Bytes\n", n);
-        return 0;
-    }
-
-    return -1;
-
-    return retcode;
-}
-
-int main()
-{
-    iface.modem_debug_on(MBED_CONF_APP_MODEM_TRACE);
-    /* Set Pin code for SIM card */
-    iface.set_sim_pin(PIN_CODE);
-
-    /* Set network credentials here, e.g., APN*/
-    iface.set_credentials(CREDENTIALS);
-
-    printf("\n\nmbed-os-example-cellular, Connecting...\n");
+/* Connect */
+iface.connect()
+```
 
-    /* Attempt to connect to a cellular network */
-    if (do_connect() == NSAPI_ERROR_OK) {
-        nsapi_error_t retcode = test_send_recv();
-        if (retcode == NSAPI_ERROR_OK) {
-            printf("\n\nSuccess. Exiting \n\n");
-            return 0;
-        }
-    }
+This example demonstrates how to establish a connection and proceed to a simple TCP echo test:
 
-    printf("\n\nFailure. Exiting \n\n");
-    return -1;
-}
-// EOF
-```
+[![View code](https://www.mbed.com/embed/?url=https://github.com/ARMmbed/mbed-os-examples-docs_only/blob/master/CellularTCP/)](https://github.com/ARMmbed/mbed-os-examples-docs_only/blob/master/CellularTCP/main.cpp)