This is an example based on mbed-os cellular APIs that demonstrates a TCP or UDP echo transaction with a public echo server. Included TPB23 NB-IoT module which is can use LGU+ in Korea.

This example is showing how to use the NB-IoT(SECOM TPB23 module) of LGU plus network in Korea. The NB-IoT module' seller provided a document on how to start based on Mbed OS 5.11. (Created by CodeZoo) This guide has been supported to the latest os version which included 5.12 ~ 5.15.

  • if you need specific version of Mbed OS, please revision of TPB23_Driver and check it out.
  • Pelion ready example code is here!

Requirement

462 320 320

320

Tested with

1. Import the application into your desktop

mbed import http://os.mbed.com/users/Daniel_Lee/code/mbed-os-example-cellular-TPB23/

cd mbed-os-example-cellular-TPB23

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: Aug  7 2019, 06:10:47


[MAIN], plmn: NULL
Establishing connection
[00000001ms][INFO][CELL]: New CellularContext  (20000a08)
[00000002ms][INFO][CELL]: CellularContext plmn NULL
[00000003ms][INFO][CELL]: CellularContext connect
[00000036ms][INFO][CELL]: RSSI -69 dBm
[00000036ms][INFO][CELL]: Start connecting (timeout 1 s)
[00000087ms][INFO][CELL]: RSSI -69 dBm
[00000116ms][INFO][CELL]: Modem ready
[00000146ms][INFO][CELL]: RSSI -69 dBm
[00000146ms][INFO][CELL]: Setup SIM (timeout 1 s)
[00001233ms][INFO][CELL]: Looked up APN internet
[00001362ms][ERR ][CELL]: AT error code 50
[00001362ms][WARN][CELL]: Packet domain event reporting set failed!
[00001393ms][INFO][CELL]: RSSI -65 dBm
[00001393ms][INFO][CELL]: Network registration (timeout 180 s)
[00001443ms][INFO][CELL]: Registering network => Attaching network
[00001473ms][INFO][CELL]: RSSI -65 dBm
[00001473ms][INFO][CELL]: Attaching network (timeout 60 s)
[00001601ms][INFO][CELL]: Found PDP context 1
[00001649ms][INFO][CELL]: Activate PDP context 1


Connection Established.
[00001671ms][INFO][CELL]: Socket 0 open
[00001707ms][INFO][CELL]: Socket 1 open
[00001748ms][INFO][CELL]: Socket create id: 1
[00001883ms][INFO][CELL]: Socket 1 sent 43 bytes to 8.8.8.8 port 53
[00004311ms][INFO][CELL]: Socket 1 recv 59 bytes from 8.8.8.8 port 53
[00004331ms][INFO][CELL]: Close socket: 1 error: 0
[00004331ms][INFO][CELL]: Socket 1 closed
[00004373ms][INFO][CELL]: Socket create id: 1
TCP: connected with echo.mbedcloudtesting.com server
[00004448ms][INFO][CELL]: Socket 0 sent 4 bytes to 52.215.34.155 port 7
TCP: Sent 4 Bytes to echo.mbedcloudtesting.com
[00007560ms][INFO][CELL]: Socket 0 recv 4 bytes
[00007580ms][INFO][CELL]: Close socket: 1 error: 0
[00007580ms][INFO][CELL]: Socket 0 closed
Received from echo server 4 Bytes
[00007581ms][INFO][CELL]: CellularContext disconnect()
[00007630ms][INFO][CELL]: cb: CellularContext disconnected


Success. Exiting
Revision:
45:63eba30af193
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SERCOMM/TPB23/SERCOMM_TPB23_CellularStack.cpp	Wed Aug 07 06:31:31 2019 +0000
@@ -0,0 +1,255 @@
+/*
+ * Copyright (c) 2017, Arm Limited and affiliates.
+ * 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 "SERCOMM_TPB23_CellularStack.h"
+#include "CellularUtil.h"
+#include "CellularLog.h"
+
+#define PACKET_SIZE_MAX 1500  //TPB23 Range is 12-1500
+
+using namespace mbed;
+using namespace mbed_cellular_util;
+
+SERCOMM_TPB23_CellularStack::SERCOMM_TPB23_CellularStack(ATHandler &atHandler, int cid, nsapi_ip_stack_t stack_type) : AT_CellularStack(atHandler, cid, stack_type)
+{
+    _at.set_urc_handler("+NSONMI:", mbed::Callback<void()>(this, &SERCOMM_TPB23_CellularStack::urc_nsonmi));
+}
+
+SERCOMM_TPB23_CellularStack::~SERCOMM_TPB23_CellularStack()
+{
+}
+
+nsapi_error_t SERCOMM_TPB23_CellularStack::socket_listen(nsapi_socket_t handle, int backlog)
+{
+    return NSAPI_ERROR_UNSUPPORTED;
+}
+
+nsapi_error_t SERCOMM_TPB23_CellularStack::socket_accept(void *server, void **socket, SocketAddress *addr)
+{
+    return NSAPI_ERROR_UNSUPPORTED;
+}
+
+nsapi_error_t SERCOMM_TPB23_CellularStack::socket_connect(nsapi_socket_t handle, const SocketAddress &address)
+{
+    CellularSocket *socket = (CellularSocket *)handle;
+
+    _at.lock();
+    if (!socket->created) {
+        const nsapi_error_t error_create = create_socket_impl(socket);
+        if (error_create != NSAPI_ERROR_OK) {
+            return error_create;
+        }
+    }
+
+    _at.cmd_start("AT+NSOCO=");
+    _at.write_int(socket->id);
+    _at.write_string(address.get_ip_address(), false);
+    _at.write_int(address.get_port());
+    _at.cmd_stop();
+    _at.resp_start();
+    _at.resp_stop();
+    _at.unlock();
+
+    if (_at.get_last_error() == NSAPI_ERROR_OK) {
+        socket->remoteAddress = address;
+        socket->connected = true;
+        return NSAPI_ERROR_OK;
+    }
+
+    return NSAPI_ERROR_NO_CONNECTION;
+}
+
+void SERCOMM_TPB23_CellularStack::urc_nsonmi()
+{
+    int sock_id = _at.read_int();
+
+    for (int i = 0; i < get_max_socket_count(); i++) {
+        CellularSocket *sock = _socket[i];
+        if (sock && sock->id == sock_id) {
+            if (sock->_cb) {
+                sock->_cb(sock->_data);
+            }
+            break;
+        }
+    }
+}
+
+int SERCOMM_TPB23_CellularStack::get_max_socket_count()
+{
+    return TPB23_SOCKET_MAX;
+}
+
+bool SERCOMM_TPB23_CellularStack::is_protocol_supported(nsapi_protocol_t protocol)
+{
+    return (protocol == NSAPI_UDP || protocol == NSAPI_TCP);
+}
+
+nsapi_error_t SERCOMM_TPB23_CellularStack::socket_close_impl(int sock_id)
+{
+    _at.cmd_start("AT+NSOCL=");
+    _at.write_int(sock_id);
+    _at.cmd_stop_read_resp();
+
+    tr_info("Close socket: %d error: %d", sock_id, _at.get_last_error());
+
+    return _at.get_last_error();
+}
+
+nsapi_error_t SERCOMM_TPB23_CellularStack::create_socket_impl(CellularSocket *socket)
+{
+    int sock_id = -1;
+    bool socketOpenWorking = false;
+
+    if (socket->proto == NSAPI_UDP) {
+        _at.cmd_start("AT+NSOCR=DGRAM,17,");
+    } else if (socket->proto == NSAPI_TCP) {
+        _at.cmd_start("AT+NSOCR=STREAM,6,");
+    } else {
+        return NSAPI_ERROR_PARAMETER;
+    }
+    _at.write_int(socket->localAddress.get_port());
+    _at.write_int(1);
+    _at.cmd_stop();
+    _at.resp_start();
+    sock_id = _at.read_int();
+    _at.resp_stop();
+
+    socketOpenWorking = (_at.get_last_error() == NSAPI_ERROR_OK);
+
+    if (!socketOpenWorking) {
+        _at.cmd_start("AT+NSOCL=0");
+        _at.cmd_stop_read_resp();
+
+        if (socket->proto == NSAPI_UDP) {
+            _at.cmd_start("AT+NSOCR=DGRAM,17,");
+        } else if (socket->proto == NSAPI_TCP) {
+            _at.cmd_start("AT+NSOCR=STREAM,6,");
+        }
+        _at.write_int(socket->localAddress.get_port());
+        _at.write_int(1);
+        _at.cmd_stop();
+        _at.resp_start();
+        sock_id = _at.read_int();
+        _at.resp_stop();
+
+        socketOpenWorking = (_at.get_last_error() == NSAPI_ERROR_OK);
+    }
+
+    if (!socketOpenWorking || (sock_id == -1)) {
+        tr_error("Socket create failed!");
+        return NSAPI_ERROR_NO_SOCKET;
+    }
+
+    // Check for duplicate socket id delivered by modem
+    for (int i = 0; i < TPB23_SOCKET_MAX; i++) {
+        CellularSocket *sock = _socket[i];
+        if (sock && sock->created && sock->id == sock_id) {
+            tr_error("Duplicate socket index: %d created:%d, sock_id: %d", i, sock->created, sock_id);
+            return NSAPI_ERROR_NO_SOCKET;
+        }
+    }
+
+    tr_info("Socket create id: %d", sock_id);
+
+    socket->id = sock_id;
+    socket->created = true;
+
+    return NSAPI_ERROR_OK;
+}
+
+nsapi_size_or_error_t SERCOMM_TPB23_CellularStack::socket_sendto_impl(CellularSocket *socket, const SocketAddress &address,
+                                                                     const void *data, nsapi_size_t size)
+{
+    int sent_len = 0;
+
+    if (size > PACKET_SIZE_MAX) {
+        return NSAPI_ERROR_PARAMETER;
+    }
+
+    char *hexstr = new char[size * 2 + 1];
+    int hexlen = char_str_to_hex_str((const char *)data, size, hexstr);
+    // NULL terminated for write_string
+    hexstr[hexlen] = 0;
+
+    if (socket->proto == NSAPI_UDP) {
+        _at.cmd_start("AT+NSOST=");
+        _at.write_int(socket->id);
+        _at.write_string(address.get_ip_address(), false);
+        _at.write_int(address.get_port());
+        _at.write_int(size);
+    } else if (socket->proto == NSAPI_TCP) {
+        _at.cmd_start("AT+NSOSD=");
+        _at.write_int(socket->id);
+        _at.write_int(size);
+    } else {
+        delete [] hexstr;
+        return NSAPI_ERROR_PARAMETER;
+    }
+
+    _at.write_string(hexstr, false);
+    _at.cmd_stop();
+    _at.resp_start();
+    // skip socket id
+    _at.skip_param();
+    sent_len = _at.read_int();
+    _at.resp_stop();
+
+    delete [] hexstr;
+
+    if (_at.get_last_error() == NSAPI_ERROR_OK) {
+        return sent_len;
+    }
+
+    return _at.get_last_error();
+}
+
+nsapi_size_or_error_t SERCOMM_TPB23_CellularStack::socket_recvfrom_impl(CellularSocket *socket, SocketAddress *address,
+                                                                       void *buffer, nsapi_size_t size)
+{
+    nsapi_size_or_error_t recv_len = 0;
+    int port;
+    char ip_address[NSAPI_IP_SIZE];
+
+    _at.cmd_start("AT+NSORF=");
+    _at.write_int(socket->id);
+    _at.write_int(size <= PACKET_SIZE_MAX ? size : PACKET_SIZE_MAX);
+    _at.cmd_stop();
+    _at.resp_start();
+    // receiving socket id
+    _at.skip_param();
+    _at.read_string(ip_address, sizeof(ip_address));
+    port = _at.read_int();
+    recv_len = _at.read_int();
+    int hexlen = _at.read_hex_string((char *)buffer, size);
+    // remaining length
+    _at.skip_param();
+    _at.resp_stop();
+
+    if (!recv_len || (recv_len == -1) || (_at.get_last_error() != NSAPI_ERROR_OK)) {
+        return NSAPI_ERROR_WOULD_BLOCK;
+    }
+
+    if (address) {
+        address->set_ip_address(ip_address);
+        address->set_port(port);
+    }
+
+    if (recv_len != hexlen) {
+        tr_error("Not received as much data as expected. Should receive: %d bytes, received: %d bytes", recv_len, hexlen);
+    }
+    return recv_len;
+}