update Pycom NBIoT example to use microATsocket project for data communication

Author: ftylitak

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "examples/pycom/nbiot/microATsocket"]
+	path = examples/pycom/nbiot/microATsocket
+	url = https://github.com/insighio/microATsocket

examples/pycom/nbiot/README.md

@@ -0,0 +1,7 @@
+Requires submodule initialization:
+
+```
+git submodule update --init --recursive
+```
+
+The implementation with the custom sockets that utilize AT commands uses project [microATsocket](https://github.com/insighio/microATsocket) to be able to send data using IPv6 addresses. In case of CoAP messages, microATsocket is advised to be used with custom build firmware with [Pull Request 429](https://github.com/pycom/pycom-micropython-sigfox/pull/429) than enables long message to be send over AT commands.

examples/pycom/nbiot/microATsocket

@@ -4,7 +4,7 @@
 import binascii
 import microcoapy
 
-from pycom_at_socket import PycomATSocket
+import microATsocket.microATsocket as socket
 
 _NBIOT_MAX_CONNECTION_TIMEOUT_MSEC=30000
 _NBIOT_APN="iot"
@@ -41,7 +41,7 @@ def disconnectNBIoT():
 
 def sendPostRequest(client):
     # About to post message...
-    messageId = client.post(_SERVER_IP, _SERVER_PORT, _COAP_POST_URL, '[{"bn":"09876543","n":"batt","u":"V","v":12}]',
+    messageId = client.post(_SERVER_IP, _SERVER_PORT, _COAP_POST_URL, '[{"bn":"09876543aacc","n":"batt","u":"V","v":12}]',
                                    "authorization=123456789", microcoapy.COAP_CONTENT_FORMAT.COAP_APPLICATION_JSON)
     print("[POST] Message Id: ", messageId)
 
@@ -62,13 +62,14 @@ def receivedMessageCallback(packet, sender):
     client.resposeCallback = receivedMessageCallback
 
     # Initialize custom socket
-    customSocket = PycomATSocket(lte)
+    sock = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM)
+    sock.setModemInstance(lte)
 
     # Use custom socket to all operations of CoAP
-    client.setCustomSocket(customSocket)
+    client.setCustomSocket(sock)
 
     sendPostRequest(client)
 
-    customSocket.close()
+    sock.close()
 
 disconnectNBIoT()

examples/pycom/nbiot/pycom_at_socket.py

@@ -0,0 +1,71 @@
+from network import LTE
+import machine
+import utime
+import binascii
+import microcoapy
+
+_NBIOT_MAX_CONNECTION_TIMEOUT_MSEC=30000
+_NBIOT_APN="iot"
+
+_SERVER_IP="2001:4860:4860::8888"
+_SERVER_PORT=5683
+_COAP_POST_URL="path/to/post/service"
+
+print("Initializing LTE...")
+lte = LTE()
+lte.init()
+
+def connectNBIoT(timeout):
+    print("Connecting LTE...")
+    if(not lte.isattached() or not lte.isconnected()):
+        lte.send_at_cmd('AT+CFUN=0')
+        lte.send_at_cmd('AT+CMEE=2')
+        lte.send_at_cmd('AT+CGDCONT=1,"IPV6","' + _NBIOT_APN + '"')
+        lte.send_at_cmd('AT+CFUN?')
+
+        start_time_activation = utime.ticks_ms()
+
+        lte.send_at_cmd('AT+CFUN=1')
+        while not lte.isattached() and (utime.ticks_ms()-start_time_activation < timeout):
+            print(".", end="")
+            machine.idle()
+
+        con_start_time_activation = utime.ticks_ms()
+        lte.connect()
+        while not lte.isconnected() and (utime.ticks_ms()-con_start_time_activation < timeout):
+            print(",", end="")
+            machine.idle()
+        print("")
+
+    return lte.isattached() and lte.isconnected()
+
+def disconnectNBIoT():
+    LTE().detach()
+
+
+def sendPostRequest(client):
+    # About to post message...
+    messageId = client.post(_SERVER_IP, _SERVER_PORT, _COAP_POST_URL, '[{"bn":"09876543","n":"batt","u":"V","v":13}]',
+                                   "authorization=123456789", microcoapy.COAP_CONTENT_FORMAT.COAP_APPLICATION_JSON)
+    print("[POST] Message Id: ", messageId)
+
+    # wait for respose to our request for 2 seconds
+    client.poll(10000)
+
+
+def receivedMessageCallback(packet, sender):
+    print('Message received:', packet.toString(), ', from: ', sender)
+
+
+
+connected = connectNBIoT(_NBIOT_MAX_CONNECTION_TIMEOUT_MSEC)
+print("LTE ok: " + str(connected))
+
+if(connected):
+    client = microcoapy.Coap()
+    # setup callback for incoming respose to a request
+    client.start()
+
+    sendPostRequest(client)
+
+disconnectNBIoT()