I'm using two SIM908 shield to communicate with each other. One of the shields will be connected to a sensor and it should send values contentiously to the second SIM908 (receiver). I'm facing a problem on the receiver side, I'm only able to receive the first SMS and when sending a new SMS it displays the first one.
The code that I'm using is from (cooking-hacks.com) where I bought the shield. In the original code the instructions were in void setup function so I moved them to void loop function to keep checking for new SMS and print any received values. I also made other minor changes. Here is the code
int8_t answer;
int x;
int onModulePin= 2;
char aux_string[30];
char SMS[200];
float fSMS;
char data[20];
void setup(){
pinMode(onModulePin, OUTPUT);
Serial.begin(115200);
Serial.println("Starting...");
power_on();
}
void loop(){
Serial.println("Setting SMS mode...");
sendATcommand("AT+CMGF=1", "OK", 1000); // sets the SMS mode to text
sendATcommand("AT+CPMS=\"SM\",\"SM\",\"SM\"", "OK", 1000); // selects the memory
answer = sendATcommand("AT+CMGR=1", "+CMGR:", 2000); // reads the first SMS (since all other messages are deleted from previous delete statment)
if (answer == 1)
{
answer = 0;
while(Serial.available() == 0);
// this loop reads the data of the SMS
do{
// if there are data in the UART input buffer, reads it and checks for the asnwer
if(Serial.available() > 0){
SMS[x] = Serial.read();
x++;
// check if the desired answer (OK) is in the response of the module
if (strstr(SMS, "OK") != NULL)
{
answer = 1;
}
}
}while(answer == 0); // Waits for the asnwer with time out
SMS[x] = '\0';
/* strtok(SMS, ",");
strtok(NULL, ",");
strtok(NULL, ",");
strtok(NULL, "\n");
strcpy(data,strtok(NULL, ""));*/
Serial.println(SMS);
//Serial.println(data);
/* fSMS= atof (data);
Serial.println(fSMS, 5);*/
}
else
{
Serial.print("error ");
Serial.println(answer, DEC);
}
Serial.println("AT+CMGDA= \"DEL ALL\"");//delete all messages from SIM card
delay(5000);
}
void power_on(){
uint8_t answer=0;
// checks if the module is started
answer = sendATcommand("AT", "OK", 2000);
if (answer == 0)
{
// power on pulse
digitalWrite(onModulePin,HIGH);
delay(3000);
digitalWrite(onModulePin,LOW);
// waits for an answer from the module
while(answer == 0){ // Send AT every two seconds and wait for the answer
answer = sendATcommand("AT", "OK", 2000);
}
}
}
int8_t sendATcommand(char* ATcommand, char* expected_answer, unsigned int timeout){
uint8_t x=0, answer=0;
char response[100];
unsigned long previous;
memset(response, '\0', 100); // Initialice the string
delay(100);
while( Serial.available() > 0) Serial.read(); // Clean the input buffer
Serial.println(ATcommand); // Send the AT command
x = 0;
previous = millis();
// this loop waits for the answer
do{
// if there are data in the UART input buffer, reads it and checks for the asnwer
if(Serial.available() != 0){
response[x] = Serial.read();
x++;
// check if the desired answer is in the response of the module
if (strstr(response, expected_answer) != NULL)
{
answer = 1;
}
}
// Waits for the asnwer with time out
}while((answer == 0) && ((millis() - previous) < timeout));
return answer;
}