CODEWITHSUNDEEP
sim900
Nikola Boskovic
Nikola Boskovic

Reputation: 31

SIM900 won't send message (+CME ERROR: invalid input value)

Last night code was working, but when I tried today I got +CME ERROR: invalid input value.

I'm using arduino uno and sim900.

Code I used is from randomnerdtutorials.

`/*********
  Complete project details at https://randomnerdtutorials.com  
*********/

#include <SoftwareSerial.h>

// Configure software serial port
SoftwareSerial SIM900(7, 8); 

void setup() {

  SIM900.begin(19200);
  Serial.begin(9600);
  
  // Send the SMS
  sendSMS();
}

void loop() { 
  
}

void sendSMS() {
  Serial.println("Sending SMS");
  // AT command to set SIM900 to SMS mode
  SIM900.print("AT+CMGF=1\r"); 
  delay(100);

  SIM900.println("AT+CMGS=\"+381601xxxxxx\""); 
  delay(100);
  
  SIM900.println("Hello"); 
  delay(100);

// End AT command with a ^Z, ASCII code 26
  SIM900.println((char)26); 
  delay(100);
  SIM900.println();
  // Give module time to send SMS
  long int time = millis();
  while ((time + 10000) > millis()) {
    while (SIM900.available()) {
      String response = SIM900.readString();
      Serial.println(response); 
    }
  }
  Serial.println("Sent");
}`

15:41:20.146 -> Sending command: AT
15:41:22.181 -> Response: 
15:41:22.181 -> OK
15:41:22.181 -> 
15:41:22.181 -> Sending command: AT+CPIN?
15:41:24.156 -> Response: 
15:41:24.188 -> +CPIN: READY
15:41:24.188 -> 
15:41:24.188 -> OK
15:41:24.188 -> 
15:41:24.188 -> Sending command: AT+CSQ
15:41:26.163 -> Response: 
15:41:26.195 -> +CSQ: 25,0
15:41:26.195 -> 
15:41:26.195 -> OK
15:41:26.195 -> 
15:41:26.195 -> Sending command: AT+CREG?
15:41:28.170 -> Response: 
15:41:28.202 -> +CREG: 0,1
15:41:28.202 -> 
15:41:28.202 -> OK
15:41:28.202 -> 
15:41:28.202 -> Sending command: AT+CSCA?
15:41:30.210 -> Response: 
15:41:30.210 -> +CSCA: "002B00330038003100360033003100300030003100300030",145
15:41:30.275 -> Sending command: AT+CMGF=1
15:41:32.229 -> Response: 
15:41:32.229 -> OK

I also tried bunch of other commands to check sim status and everything works properly:

I had also tried 2 other sim cards and got the same issue. I'm assuming that something is wrong with my sim900 module. I tried ATZ to reset the module and also tried manually turning device off and on and nothing changed.

Any suggestions?

Thank you in advance.

Upvotes: 0

Views: 101

Answers (1)

Jib
Jib

Reputation: 1582

As per the datasheet, the command syntax is AT+CMGS=<number><CR><message><CTRL-Z>. So it looks like you are missing the CR character (\r) when you send the AT+CMGS command to the modem.

Your line should be:

SIM900.println("AT+CMGS=\"+381601xxxxxx\"\r");

Maybe you should also change the CTRL-Z print to:

SIM900.println("\x1a");

Upvotes: 0

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