GSM Smart Socket

1/*
2 * Date       : 6 March 2021 
3 * Author     : Erick H Moshi
4  * Description: GSM based switch
5 */
6 
7#include <SoftwareSerial.h> // Library  for using serial communication
8SoftwareSerial SIM800(7, 8); // Pins 7, 8 are  used as used as software serial pins
9
10String incomingData;       // for storing  incoming serial data
11String message = "";       // A String for storing the  message
12String lineState = "IDLE"; // To initially set the state to idle once  booted or in cases of power cuts
13int relay_pin = 13;        // Initialized a  pin for relay module
14
15void setup()
16{
17  Serial.begin(115200); // baudrate  for serial monitor
18  SIM800.begin(19200);  // baudrate for GSM shield
19
20  pinMode(relay_pin, OUTPUT);     // Setting erlay pin as output pin
21  digitalWrite(relay_pin,  HIGH);  // Making relay pin initailly low
22
23  delay(30000);
24  
25  Serial.println("Initializing  ...");
26  delay(1000);
27
28  // set SMS mode to text mode
29  SIM800.print("AT+CMGF=1\
");  
30  delay(5000);
31
32  SIM800.print("AT+CMGD=1,4\
"); // delete all sms  on sim card
33  delay(5000);
34  
35  // set gsm module to show the output on  serial out
36  SIM800.print("AT+CNMI=2,2,0,0,0\
"); 
37  delay(5000);
38
39  // Retrieve own mobile number from SIM
40  Serial.println(F("Attempting to retrieve  own MSISDN number from sim"));
41  SIM800.print("AT+CNUM\
");
42  delay(5000);
43
44  // Enable caller ID on incoming calls
45  Serial.println(F("Enabling Caller  ID on incoming calls"));
46  SIM800.print("AT+CLIP=1\
");
47  Serial.println("Setup  complete!");
48  delay(5000);
49
50  // Send text to alert that system is back  online after a power cut/ when switched on
51  SIM800.println("AT+CMGF=1");
52  delay(100);
53  SIM800.println("AT+CMGS=\\"+ZZZxxxxxxxxx\\""); // Send SMS  to the phone number, this will alert you that the system is on
54  delay(100);
55  SIM800.println("SYSTEM ONLINE"); // The content of the SMS
56  delay(100);
57  SIM800.println((char)26);                    // ASCII code of CTRL+Z
58  delay(100);
59  SIM800.println();
60  delay(1000);
61  
62}
63
64void loop()
65{
66  //Function  for receiving sms
67  receive_message();
68
69  // if received command is to  turn on relay
70  if(incomingData.indexOf("LINE_ON")>=0)
71  {
72    digitalWrite(relay_pin,  HIGH);// set to high since we are using the Normarlly Closed side of the relay
73    message = "Line is turned ON";
74    lineState = "ON";
75    // Send a  sms back to confirm that the relay is turned on
76    send_message(message);
77  }
78  
79  // if received command is to turn off relay
80  if(incomingData.indexOf("LINE_OFF")>=0)
81  {
82    digitalWrite(relay_pin, LOW);//Set to low since we are using the Normally  Closed side of the relay and Low will activate the relay switching the line off
83    message = "Line is turned OFF";
84    lineState = "OFF"; 
85    // Send  a sms back to confirm that the relay is turned off
86    send_message(message);
87  }
88  if(incomingData.indexOf("STATE")>=0)
89  {
90    message = "Line state  is " + lineState;
91    send_message(message);
92    Serial.println("Line state  resquest");
93    message = "";
94  }
95}
96
97void receive_message()
98{
99  if (SIM800.available() > 0)
100  {
101    incomingData = SIM800.readString();  // Get the data from the serial port.
102    Serial.print(incomingData); 
103    delay(10);  
104  }
105}
106
107void send_message(String message)
108{
109  SIM800.println("AT+CMGF=1");                 //Set the GSM Module in Text Mode
110  delay(100);  
111  SIM800.println("AT+CMGS=\\"+ZZZxxxxxxxxx\\"");  // Sends feedback text to the phone number
112  delay(100);
113  SIM800.println(message);                     // The SMS text you want to send
114  delay(100);
115  SIM800.println((char)26);                    // ASCII code of CTRL+Z
116  delay(100);
117  SIM800.println();
118  delay(1000);  
119}