I use the code from http://www.instructables.com/id/Control-the-relays-via-GPRS-SMS/?ALLSTEPS to control two LEDs with SMS commands.
It has worked!
Suddenly, I can only control the Arduino circuit with SMS containing 3 characters.
If I connect the GSM shiled to a serial monitor, I see SMS containing more than three characters.
It seems that something is wrong in the code or something has happened to the Arduino.
A few weeks ago, everything worked and I have not changed in the code ...
What could be wrong?
#include <SoftwareSerial.h>
//http://www.instructables.com/id/Control-the-relays-via-GPRS-SMS/?ALLSTEPS
// 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 GreenLed=6;
int RedLed=7;
void setup()
{
Serial.begin(19200); // the GPRS baud rate
// Initialize PINs
pinMode( 6, OUTPUT );
pinMode( 7, OUTPUT );
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("onc") >= 0 ){
digitalWrite( GreenLed, HIGH );
}
if( sms.indexOf("ond") >= 0 ){
digitalWrite( RedLed, HIGH );
}
if( sms.indexOf("offc") >= 0 ){
digitalWrite( GreenLed, LOW );
}
if( sms.indexOf("offd") >= 0 ){
digitalWrite( RedLed, LOW );
}
Serial.println("AT+CMGD=1,4"); // delete last SMS
}
// 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;
}