Arduino Based Home Automation System

Question

I am working on my project of home automation system using Arduino GSM SIM900 & four channel relay module. I am facing a problem in my code. Can any one help me on this, SMS is receiving but its not switching the relays?

#include <SoftwareSerial.h>
// EN: String buffer for the GPRS shield message
String msg = String("");
// EN: Set to 1 when the next GPRS shield message will contains the SMS message
int SmsContentFlag = 0;
//control pins of relay.
int relay_a=4;
int relay_b=5;
int relay_c=6;
int relay_d=7;
// EN: Code PIN of the SIM card (if applied)
//String SIM_PIN_CODE = String( "XXXX" );
void setup()
{
 Serial.begin(19200); // the GPRS baud rate
 // Initialize PINs
 pinMode( 4, OUTPUT ); 
 pinMode( 5, OUTPUT ); 
 pinMode( 6, OUTPUT ); 
 pinMode( 7, OUTPUT ); 
 digitalWrite( 4, LOW ); 
 digitalWrite( 5, LOW ); 
 digitalWrite( 6, LOW );
 digitalWrite( 7, LOW );
 Serial.println( "AT+CMGF=1" ); 
 delay(200);
}
void loop()
{
 char SerialInByte;
 if(Serial.available())
 { 
 SerialInByte = (unsigned char)Serial.read();
 delay(5);
 // -------------------------------------------------------------------
 // EN: Program also listen to the GPRS shield message.
 // -------------------------------------------------------------------
 // EN: If the message ends with <CR> then process the message
 if( SerialInByte == 13 ){
 // EN: Store the char into the message buffer
 ProcessGprsMsg();
 }
 if( SerialInByte == 10 ){
 // EN: Skip Line feed
 }
 else {
 // EN: store the current character in the message string buffer
 msg += String(SerialInByte);
 }
 } 
}
// EN: Make action based on the content of the SMS. 
// Notice than SMS content is the result of the processing of several GPRS shield messages.
void ProcessSms( String sms ){
 if( sms.indexOf("ona") >= 0 ){
 digitalWrite( relay_a, HIGH );
 }
 if( sms.indexOf("onb") >= 0 ){
 digitalWrite( relay_b, HIGH );
 }
 if( sms.indexOf("onc") >= 0 ){
 digitalWrite( relay_c, HIGH );
 }
 if( sms.indexOf("ond") >= 0 ){
 digitalWrite( relay_d, HIGH );
 }
 if( sms.indexOf("offa") >= 0 ){
 digitalWrite( relay_a, LOW );
 }
 if( sms.indexOf("offb") >= 0 ){
 digitalWrite( relay_b, LOW );
 }
 if( sms.indexOf("offc") >= 0 ){
 digitalWrite( relay_c, LOW );
 }
 if( sms.indexOf("offd") >= 0 ){
 digitalWrite( relay_d, LOW );
 }
}
// EN: Request Text Mode for SMS messaging
void GprsTextModeSMS(){
 Serial.println( "AT+CMGF=1" );
}
void GprsReadSmsStore( String SmsStorePos ){
 Serial.print( "AT+CMGR=" );
 Serial.println( SmsStorePos );
}
// EN: Clear the GPRS shield message buffer
void ClearGprsMsg(){
 msg = "";
}
// EN: interpret the GPRS shield message and act appropiately
void ProcessGprsMsg() {
 if( msg.indexOf( "Call Ready" ) >= 0 ){
 // Serial.println( "*** GPRS Shield registered on Mobile Network ***" );
 GprsTextModeSMS();
 }
 // EN: unsolicited message received when getting a SMS message
 if( msg.indexOf( "+CMTI" ) >= 0 ){
 // Serial.println( "*** SMS Received ***" );
 // EN: Look for the coma in the full message (+CMTI: "SM",6)
 // In the sample, the SMS is stored at position 6
 int iPos = msg.indexOf( "," );
 String SmsStorePos = msg.substring( iPos+1 );
 // Serial.print( "SMS stored at " );
 // Serial.println( SmsStorePos ); 
 // EN: Ask to read the SMS store
 GprsReadSmsStore( SmsStorePos );
 }
 // EN: SMS store readed through UART (result of GprsReadSmsStore request) 
 if( msg.indexOf( "+CMGR:" ) >= 0 ){
 // EN: Next message will contains the BODY of SMS
 SmsContentFlag = 1;
 // EN: Following lines are essentiel to not clear the flag!
 ClearGprsMsg();
 return;
 }
 // EN: +CMGR message just before indicate that the following GRPS Shield message 
 // (this message) will contains the SMS body 
 if( SmsContentFlag == 1 ){
 // Serial.println( "*** SMS MESSAGE CONTENT ***" );
 // Serial.println( msg );
 // Serial.println( "*** END OF SMS MESSAGE ***" );
 ProcessSms( msg );
 }
 ClearGprsMsg();
 // EN: Always clear the flag
 SmsContentFlag = 0; 
}

• user6569: Not related to Arduino, but I think the people reading the question might be interested to know z-wave protocol appears to be in, but not turned on, Windows 10 for the Pi.

Answer 1

I think you'd want to include a call to ClearGprsMsg() right before the line GprsReadSmsStore( SmsStorePos );.

Then, msg += String(SerialInByte); is probably wrong, see for example http://arduino.cc/en/Tutorial/StringConstructors:

// using a constant integer:
stringOne = String(13); 
Serial.println(stringOne); // prints "13"