Added sleep command

Author: xoseperez

src/TheThingsNetwork.cpp

@@ -874,3 +874,20 @@ void TheThingsNetwork::stateMessage(uint8_t type, uint8_t indexMsg, const char *
     debugPrintLn();
   }
 }
+
+void TheThingsNetwork::sleep(unsigned long msec) {
+    if (100 < msec && msec < 4294967296) {
+        while (modemStream->available()) {
+          modemStream->read();
+        }
+        debugPrint(F(SENDING));
+        sendCommand(SYS_TABLE, SYS_PREFIX, true);
+        sendCommand(SYS_TABLE, SYS_SLEEP, true);
+        char buffer[10];
+        sprintf(buffer, "%ld", msec);
+        modemStream->write(buffer);
+        debugPrint(buffer);
+        modemStream->write(SEND_MSG);
+        debugPrintLn();
+    }
+}

src/TheThingsNetwork.h

@@ -90,6 +90,7 @@ class TheThingsNetwork
     bool personalize(const char *devAddr, const char *nwkSKey, const char *appSKey);
     bool personalize();
     ttn_response_t sendBytes(const byte* payload, size_t length, port_t port = 1, bool confirm = false);
+    void sleep(unsigned long mseconds);
     int8_t poll(port_t port = 1, bool confirm = false);
 };