Add example for sending SMS only

examples/SendSMS/SendSMS.ino

@@ -0,0 +1,42 @@
+/*
+ * This example shows how to send an SMS message using the Arduino_Cellular library.
+ * 
+ * Instructions:
+ * 1. Insert a SIM card with or without PIN code in the Arduino Pro 4G Module.
+ * 2. Provide sufficient power to the Arduino Pro 4G Module. Ideally, use a 5V power supply
+ *    with a current rating of at least 2A and connect it to the VIN and GND pins.
+ * 3. Make sure the SIM card has enough credit to send SMS messages.
+ * 4. Specify the APN, GPRS username, and GPRS password of your mobile network provider.
+ * 5. Specify the PIN code of your SIM card if it has one.
+ * 6. Specify the phone number of the recipient and the message you want to send. 
+ * 7. Upload the sketch to the connected Arduino board.
+ * 
+ * Initial author: Sebastian Romero @sebromero
+ */
+#include "ArduinoCellular.h"
+
+const char apn[]      = "internet";
+const char gprsUser[] = "";
+const char gprsPass[] = "";
+
+ArduinoCellular cellular = ArduinoCellular();
+
+void setup(){
+    Serial.begin(115200);
+    while (!Serial);
+    delay(1000); // Give the serial monitor some time to start
+
+    cellular.begin();
+    String pinCode = "1234"; // If your SIM card has a PIN code, specify it here
+
+    Serial.println("Connecting to network...");
+    cellular.connect(apn, gprsUser, gprsPass, pinCode);
+
+    Serial.println("Sending SMS...");
+    cellular.sendSMS("+41791234567", "bleep bleep");
+    Serial.println("Done.");
+}
+
+void loop(){
+    delay(1000);
+}