EDIT: guess i got greedy and tried the first code i found online. will come back after further research.
hi everyone
i am new to arduino and i am trying to control my relays over GSM. i have a sim900 module and found the following code online. it is to control 4 relays with sms. i am not able to get it to work! i have opened the arduino IDE serial monitor and its blank. i have installed Puttty to monitor serial data, only one in ten times i am able to see the test PRINT i have given. i have tried several other sample code. none of them give the desired output. am i doing something wrong with my connections? i have Leonardo and the code below uses hardware serial. i connected Tx of sim900a to Rx(pin0) for Arduino and Rx to Tx(pin1) and Ground of sim900a to arduino ground.
the sim900module appears to work fine, power light is on, signal light blinks every three seconds and ring light comes on when i call the number and ring light blinks when i send it a text message. i dont have rs232 to usb cable at the moment. any way i can find out what i am doing wrong?
#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;
};
the board i purchased came with no headers and an onboard rs232 port. i have soldered the Tx Rx and Gnd header pins. i think i have done a decent job with that. there is no shorting between the pins and there is continuity from soldered pin end to Tx pin of rs232 Tx pin(used a multimeter, didnt know how else to check) could this be a problem? did i do something wrong?