This example use mbed-os default network interface through Cellular PDP context class . It use UDP or TCP socket with the given echo server and performs an echo transaction. This program can be used on the C027, C030-U201 and C030-R412M boards.

Revision:
0:b0d61d94aba5
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Fri Sep 20 11:53:43 2019 +0500
@@ -0,0 +1,289 @@
+/*
+ * Copyright (c) 2017 ARM Limited. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ * Licensed under the Apache License, Version 2.0 (the License); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an AS IS BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "mbed.h"
+#include "common_functions.h"
+#include "CellularNonIPSocket.h"
+#include "CellularDevice.h"
+#include "UDPSocket.h"
+#include "CellularLog.h"
+
+#define UDP 0
+#define TCP 1
+#define NONIP 2
+
+// Number of retries /
+#define RETRY_COUNT 3
+
+NetworkInterface *iface;
+
+// Echo server hostname
+const char *host_name = MBED_CONF_APP_ECHO_SERVER_HOSTNAME;
+
+// Echo server port (same for TCP and UDP)
+const int port = MBED_CONF_APP_ECHO_SERVER_PORT;
+
+static rtos::Mutex trace_mutex;
+
+#if MBED_CONF_MBED_TRACE_ENABLE
+static void trace_wait()
+{
+    trace_mutex.lock();
+}
+
+static void trace_release()
+{
+    trace_mutex.unlock();
+}
+
+static char time_st[50];
+
+static char* trace_time(size_t ss)
+{
+    snprintf(time_st, 49, "[%08llums]", Kernel::get_ms_count());
+    return time_st;
+}
+
+static void trace_open()
+{
+    mbed_trace_init();
+    mbed_trace_prefix_function_set( &trace_time );
+
+    mbed_trace_mutex_wait_function_set(trace_wait);
+    mbed_trace_mutex_release_function_set(trace_release);
+
+    mbed_cellular_trace::mutex_wait_function_set(trace_wait);
+    mbed_cellular_trace::mutex_release_function_set(trace_release);
+}
+
+static void trace_close()
+{
+    mbed_cellular_trace::mutex_wait_function_set(NULL);
+    mbed_cellular_trace::mutex_release_function_set(NULL);
+
+    mbed_trace_free();
+}
+#endif // #if MBED_CONF_MBED_TRACE_ENABLE
+
+Thread dot_thread(osPriorityNormal, 512);
+
+void print_function(const char *format, ...)
+{
+    trace_mutex.lock();
+    va_list arglist;
+    va_start( arglist, format );
+    vprintf(format, arglist);
+    va_end( arglist );
+    trace_mutex.unlock();
+}
+
+void dot_event()
+{
+    while (true) {
+        ThisThread::sleep_for(4000);
+        if (iface && iface->get_connection_status() == NSAPI_STATUS_GLOBAL_UP) {
+            break;
+        } else {
+            trace_mutex.lock();
+            printf(".");
+            fflush(stdout);
+            trace_mutex.unlock();
+        }
+    }
+}
+
+/**
+ * Connects to the Cellular Network
+ */
+nsapi_error_t do_connect()
+{
+    nsapi_error_t retcode = NSAPI_ERROR_OK;
+    uint8_t retry_counter = 0;
+
+    while (iface->get_connection_status() != NSAPI_STATUS_GLOBAL_UP) {
+        retcode = iface->connect();
+        if (retcode == NSAPI_ERROR_AUTH_FAILURE) {
+            print_function("\n\nAuthentication Failure. Exiting application\n");
+        } else if (retcode == NSAPI_ERROR_OK) {
+            print_function("\n\nConnection Established.\n");
+        } else if (retry_counter > RETRY_COUNT) {
+            print_function("\n\nFatal connection failure: %d\n", retcode);
+        } else {
+            print_function("\n\nCouldn't connect: %d, will retry\n", retcode);
+            retry_counter++;
+            continue;
+        }
+        break;
+    }
+    return retcode;
+}
+
+/**
+ * Opens:
+ * - UDP or TCP socket with the given echo server and performs an echo
+ *   transaction retrieving current.
+ * - Cellular Non-IP socket for which the data delivery path is decided
+ *   by network's control plane CIoT optimisation setup, for the given APN.
+ */
+nsapi_error_t test_send_recv()
+{
+    nsapi_size_or_error_t retcode;
+#if MBED_CONF_APP_SOCK_TYPE == TCP
+    TCPSocket sock;
+#elif MBED_CONF_APP_SOCK_TYPE == UDP
+    UDPSocket sock;
+#elif MBED_CONF_APP_SOCK_TYPE == NONIP
+    CellularNonIPSocket sock;
+#endif
+
+#if MBED_CONF_APP_SOCK_TYPE == NONIP
+    retcode = sock.open((CellularContext*)iface);
+#else
+    retcode = sock.open(iface);
+#endif
+
+    if (retcode != NSAPI_ERROR_OK) {
+#if MBED_CONF_APP_SOCK_TYPE == TCP
+        print_function("TCPSocket.open() fails, code: %d\n", retcode);
+#elif MBED_CONF_APP_SOCK_TYPE == UDP
+        print_function("UDPSocket.open() fails, code: %d\n", retcode);
+#elif MBED_CONF_APP_SOCK_TYPE == NONIP
+        print_function("CellularNonIPSocket.open() fails, code: %d\n", retcode);
+#endif
+        return -1;
+    }
+
+    int n = 0;
+    const char *echo_string = "TEST";
+    char recv_buf[4];
+
+    sock.set_timeout(15000);
+
+#if MBED_CONF_APP_SOCK_TYPE == NONIP
+    retcode = sock.send((void*) echo_string, strlen(echo_string));
+    if (retcode < 0) {
+        print_function("CellularNonIPSocket.send() fails, code: %d\n", retcode);
+        return -1;
+    } else {
+        print_function("CellularNonIPSocket: Sent %d Bytes\n", retcode);
+    }
+
+    n = sock.recv((void*) recv_buf, sizeof(recv_buf));
+
+#else
+
+    SocketAddress sock_addr;
+    retcode = iface->gethostbyname(host_name, &sock_addr);
+    if (retcode != NSAPI_ERROR_OK) {
+        print_function("Couldn't resolve remote host: %s, code: %d\n", host_name, retcode);
+        return -1;
+    }
+
+    sock_addr.set_port(port);
+
+#if MBED_CONF_APP_SOCK_TYPE == TCP
+    retcode = sock.connect(sock_addr);
+    if (retcode < 0) {
+        print_function("TCPSocket.connect() fails, code: %d\n", retcode);
+        return -1;
+    } else {
+        print_function("TCP: connected with %s server\n", host_name);
+    }
+    retcode = sock.send((void*) echo_string, strlen(echo_string));
+    if (retcode < 0) {
+        print_function("TCPSocket.send() fails, code: %d\n", retcode);
+        return -1;
+    } else {
+        print_function("TCP: Sent %d Bytes to %s\n", retcode, host_name);
+    }
+
+    n = sock.recv((void*) recv_buf, sizeof(recv_buf));
+#else
+
+    retcode = sock.sendto(sock_addr, (void*) echo_string, strlen(echo_string));
+    if (retcode < 0) {
+        print_function("UDPSocket.sendto() fails, code: %d\n", retcode);
+        return -1;
+    } else {
+        print_function("UDP: Sent %d Bytes to %s\n", retcode, host_name);
+    }
+
+    n = sock.recvfrom(&sock_addr, (void*) recv_buf, sizeof(recv_buf));
+#endif
+#endif
+
+    sock.close();
+
+    if (n > 0) {
+        print_function("Received from echo server %d Bytes\n", n);
+        return 0;
+    }
+
+    return -1;
+}
+
+int main()
+{
+    print_function("\n\nmbed-os-example-cellular\n");
+    print_function("\n\nBuilt: %s, %s\n", __DATE__, __TIME__);
+#ifdef MBED_CONF_NSAPI_DEFAULT_CELLULAR_PLMN
+    print_function("\n\n[MAIN], plmn: %s\n", (MBED_CONF_NSAPI_DEFAULT_CELLULAR_PLMN ? MBED_CONF_NSAPI_DEFAULT_CELLULAR_PLMN : "NULL"));
+#endif
+
+    print_function("Establishing connection\n");
+#if MBED_CONF_MBED_TRACE_ENABLE
+    trace_open();
+#else
+    dot_thread.start(dot_event);
+#endif // #if MBED_CONF_MBED_TRACE_ENABLE
+
+#if MBED_CONF_APP_SOCK_TYPE == NONIP
+    iface = CellularContext::get_default_nonip_instance();
+#else
+    iface = CellularContext::get_default_instance();
+#endif
+
+    MBED_ASSERT(iface);
+
+    // sim pin, apn, credentials and possible plmn are taken automatically from json when using NetworkInterface::set_default_parameters()
+    iface->set_default_parameters();
+
+    nsapi_error_t retcode = NSAPI_ERROR_NO_CONNECTION;
+
+    /* Attempt to connect to a cellular network */
+    if (do_connect() == NSAPI_ERROR_OK) {
+        retcode = test_send_recv();
+    }
+
+    if (iface->disconnect() != NSAPI_ERROR_OK) {
+        print_function("\n\n disconnect failed.\n\n");
+    }
+
+    if (retcode == NSAPI_ERROR_OK) {
+        print_function("\n\nSuccess. Exiting \n\n");
+    } else {
+        print_function("\n\nFailure. Exiting \n\n");
+    }
+
+#if MBED_CONF_MBED_TRACE_ENABLE
+    trace_close();
+#else
+    dot_thread.terminate();
+#endif // #if MBED_CONF_MBED_TRACE_ENABLE
+
+    return 0;
+}
+// EOF