This is an example based on mbed-os cellular APIs that demonstrates a TCP or UDP echo transaction with a public echo server. Especially, BG96 operation check based Mbed OS 5.11, tested via SK Telecom in Korea

This code could be access via Cat.M1(BG96 module) of SK telecom network in Korea. Need a WIZnet BG96 board and development board. Before using this code, must be checking your modem is authorized or not from SK telecom. This code is based on Mbed OS 5.11.5.

/media/uploads/Daniel_Lee/img_8560.jpg

Tested with

  • DISCOVERY_L485VG_IOT01A
  • K66F
  • K64F

1. Import the application into your desktop

 mbed import https://os.mbed.com/users/Daniel_Lee/code/mbed-os-example-cellular-BG96_os511/

 cd mbed-os-example-cellular-BG96_os511

2. Compile and program

mbed compile -t <toolchain> -m <TARGET_BOARD>

(supported toolchains : GCC_ARM / ARM / IAR)

3. Download binary to a target board

4. Result

mbed-os-example-cellular


Built: Jun  4 2019, 13:45:53


[MAIN], plmn: (null)
Modem power on
Establishing connection
..

Connection Established.
TCP: connected with echo.mbedcloudtesting.com server
TCP: Sent 4 Bytes to echo.mbedcloudtesting.com
...Received from echo server 4 Bytes
...

Success. Exiting

5. Patched code

If need more information such as how to test, please look at https://os.mbed.com/teams/mbed-os-examples/code/mbed-os-example-cellular/.

Revision:
6:5678c0b6f74e
Parent:
2:0f644d6045cf
Child:
11:23ea0907186e
--- a/main.cpp	Wed Apr 11 06:30:27 2018 +0100
+++ b/main.cpp	Thu May 10 05:17:02 2018 +0100
@@ -18,6 +18,7 @@
 #include "common_functions.h"
 #include "UDPSocket.h"
 #include "OnboardCellularInterface.h"
+#include "CellularLog.h"
 
 #define UDP 0
 #define TCP 1
@@ -51,65 +52,93 @@
 // Echo server port (same for TCP and UDP)
 const int port = 7;
 
-Mutex PrintMutex;
+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);
+}
+
+static void trace_close()
+{
+    mbed_trace_free();
+}
+#endif // #if MBED_CONF_MBED_TRACE_ENABLE
+
 Thread dot_thread(osPriorityNormal, 512);
 
-#define PRINT_TEXT_LENGTH 128
-char print_text[PRINT_TEXT_LENGTH];
-void print_function(const char *input_string)
+void print_function(const char *format, ...)
 {
-    PrintMutex.lock();
-    printf("%s", input_string);
-    fflush(NULL);
-    PrintMutex.unlock();
+    trace_mutex.lock();
+    va_list arglist;
+    va_start( arglist, format );
+    vprintf(format, arglist);
+    va_end( arglist );
+    trace_mutex.unlock();
 }
 
 void dot_event()
 {
-
     while (true) {
-        wait(4);
+        Thread::wait(4000);
         if (!iface.is_connected()) {
-            print_function(".");
+            trace_mutex.lock();
+            printf(".");
+            fflush(stdout);
+            trace_mutex.unlock();
         } else {
             break;
         }
     }
-
 }
 
-
 /**
  * Connects to the Cellular Network
  */
 nsapi_error_t do_connect()
 {
-    nsapi_error_t retcode;
+    nsapi_error_t retcode = NSAPI_ERROR_OK;
     uint8_t retry_counter = 0;
 
     while (!iface.is_connected()) {
-
         retcode = iface.connect();
         if (retcode == NSAPI_ERROR_AUTH_FAILURE) {
             print_function("\n\nAuthentication Failure. Exiting application\n");
-            return retcode;
-        } else if (retcode != NSAPI_ERROR_OK) {
-            snprintf(print_text, PRINT_TEXT_LENGTH, "\n\nCouldn't connect: %d, will retry\n", retcode);
-            print_function(print_text);
+        } 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;
-        } else if (retcode != NSAPI_ERROR_OK && retry_counter > RETRY_COUNT) {
-            snprintf(print_text, PRINT_TEXT_LENGTH, "\n\nFatal connection failure: %d\n", retcode);
-            print_function(print_text);
-            return retcode;
         }
-
         break;
     }
-
-    print_function("\n\nConnection Established.\n");
-
-    return NSAPI_ERROR_OK;
+    return retcode;
 }
 
 /**
@@ -127,17 +156,14 @@
 
     retcode = sock.open(&iface);
     if (retcode != NSAPI_ERROR_OK) {
-        snprintf(print_text, PRINT_TEXT_LENGTH, "UDPSocket.open() fails, code: %d\n", retcode);
-        print_function(print_text);
+        print_function("UDPSocket.open() fails, code: %d\n", retcode);
         return -1;
     }
 
     SocketAddress sock_addr;
     retcode = iface.gethostbyname(host_name, &sock_addr);
     if (retcode != NSAPI_ERROR_OK) {
-        snprintf(print_text, PRINT_TEXT_LENGTH, "Couldn't resolve remote host: %s, code: %d\n", host_name,
-               retcode);
-        print_function(print_text);
+        print_function("Couldn't resolve remote host: %s, code: %d\n", host_name, retcode);
         return -1;
     }
 
@@ -150,21 +176,17 @@
 #if MBED_CONF_APP_SOCK_TYPE == TCP
     retcode = sock.connect(sock_addr);
     if (retcode < 0) {
-        snprintf(print_text, PRINT_TEXT_LENGTH, "TCPSocket.connect() fails, code: %d\n", retcode);
-        print_function(print_text);
+        print_function("TCPSocket.connect() fails, code: %d\n", retcode);
         return -1;
     } else {
-        snprintf(print_text, PRINT_TEXT_LENGTH, "TCP: connected with %s server\n", host_name);
-        print_function(print_text);
+        print_function("TCP: connected with %s server\n", host_name);
     }
     retcode = sock.send((void*) echo_string, sizeof(echo_string));
     if (retcode < 0) {
-        snprintf(print_text, PRINT_TEXT_LENGTH, "TCPSocket.send() fails, code: %d\n", retcode);
-        print_function(print_text);
+        print_function("TCPSocket.send() fails, code: %d\n", retcode);
         return -1;
     } else {
-        snprintf(print_text, PRINT_TEXT_LENGTH, "TCP: Sent %d Bytes to %s\n", retcode, host_name);
-        print_function(print_text);
+        print_function("TCP: Sent %d Bytes to %s\n", retcode, host_name);
     }
 
     n = sock.recv((void*) recv_buf, sizeof(recv_buf));
@@ -172,12 +194,10 @@
 
     retcode = sock.sendto(sock_addr, (void*) echo_string, sizeof(echo_string));
     if (retcode < 0) {
-        snprintf(print_text, PRINT_TEXT_LENGTH, "UDPSocket.sendto() fails, code: %d\n", retcode);
-        print_function(print_text);
+        print_function("UDPSocket.sendto() fails, code: %d\n", retcode);
         return -1;
     } else {
-        snprintf(print_text, PRINT_TEXT_LENGTH, "UDP: Sent %d Bytes to %s\n", retcode, host_name);
-        print_function(print_text);
+        print_function("UDP: Sent %d Bytes to %s\n", retcode, host_name);
     }
 
     n = sock.recvfrom(&sock_addr, (void*) recv_buf, sizeof(recv_buf));
@@ -186,8 +206,7 @@
     sock.close();
 
     if (n > 0) {
-        snprintf(print_text, PRINT_TEXT_LENGTH, "Received from echo server %d Bytes\n", n);
-        print_function(print_text);
+        print_function("Received from echo server %d Bytes\n", n);
         return 0;
     }
 
@@ -196,28 +215,38 @@
 
 int main()
 {
-
-    iface.modem_debug_on(MBED_CONF_APP_MODEM_TRACE);
+    print_function("\n\nmbed-os-example-cellular\n");
+    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
     /* Set Pin code for SIM card */
     iface.set_sim_pin(MBED_CONF_APP_SIM_PIN_CODE);
 
-    /* Set network credentials here, e.g., APN*/
+    /* Set network credentials here, e.g., APN */
     iface.set_credentials(MBED_CONF_APP_APN, MBED_CONF_APP_USERNAME, MBED_CONF_APP_PASSWORD);
 
-    print_function("\n\nmbed-os-example-cellular\n");
-    print_function("Establishing connection ");
-    dot_thread.start(dot_event);
+    /* Set the modem debug on/off */
+    iface.modem_debug_on(MBED_CONF_APP_MODEM_TRACE);
+
+    nsapi_error_t retcode = NSAPI_ERROR_NO_CONNECTION;
 
     /* 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) {
-            print_function("\n\nSuccess. Exiting \n\n");
-            return 0;
-        }
+        retcode = test_send_recv();
     }
 
-    print_function("\n\nFailure. Exiting \n\n");
-    return -1;
+    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();
+#endif // #if MBED_CONF_MBED_TRACE_ENABLE
+
+    return 0;
 }
 // EOF