A6 A7 gateway (GSM GPRS) (#195)

* init 2G gateway with SMS sending and receiving

* A6lib add

* add 2Ggateway call from setup and loop

* add schematic and image

lib/A6lib/examples/sms/sms.ino

@@ -0,0 +1,51 @@
+#include <A6lib.h>
+
+#ifdef ESP8266
+#define D0 0
+#define D5 8
+#define D6 7
+#endif
+
+// Instantiate the library with TxPin, RxPin.
+A6lib A6l(D6, D5);
+
+int unreadSMSLocs[30] = {0};
+int unreadSMSNum = 0;
+SMSmessage sms;
+
+void setup() {
+    Serial.begin(115200);
+
+    delay(1000);
+
+    // Power-cycle the module to reset it.
+    A6l.powerCycle(D0);
+    A6l.blockUntilReady(9600);
+}
+
+void loop() {
+    String myNumber = "+1132352890";
+
+    callInfo cinfo = A6l.checkCallStatus();
+    if (cinfo.direction == DIR_INCOMING) {
+        if (myNumber.endsWith(cinfo.number)) {
+            // If the number that sent the SMS is ours, reply.
+            A6l.sendSMS(myNumber, "I can't come to the phone right now, I'm a machine.");
+            A6l.hangUp();
+        }
+
+        // Get the memory locations of unread SMS messages.
+        unreadSMSNum = A6l.getUnreadSMSLocs(unreadSMSLocs, 30);
+
+        for (int i = 0; i < unreadSMSNum; i++) {
+            Serial.print("New message at index: ");
+            Serial.println(unreadSMSLocs[i], DEC);
+
+            sms = A6l.readSMS(unreadSMSLocs[i]);
+            Serial.println(sms.number);
+            Serial.println(sms.date);
+            Serial.println(sms.message);
+        }
+        delay(1000);
+    }
+}