Help for code SIM800L

Projects Networking, Protocols, and Devices
1

I'm doing a school project to finish the last year of school. I want to use the SIM800l module to send messages when the accelerometer detects that there has been an accident, but I have a problem. I bought the sensor and before having to program it for my project, I tested it first with a simple code to send messages. But it gives an error, it doesn't even get past the "Initialize" message.

The code is this:

#include <SoftwareSerial.h>

//Create software serial object to communicate with SIM800L
SoftwareSerial mySerial(3, 2); //SIM800L Tx & Rx is connected to Arduino #3 & #2

void setup()
{
  //Begin serial communication with Arduino and Arduino IDE (Serial Monitor)
  Serial.begin(9600);
  
  //Begin serial communication with Arduino and SIM800L
  mySerial.begin(9600);

  Serial.println("Initializing...");
  delay(1000);

  mySerial.println("AT"); //Once the handshake test is successful, it will back to OK
  updateSerial();
  mySerial.println("AT+CSQ"); //Signal quality test, value range is 0-31 , 31 is the best
  updateSerial();
  mySerial.println("AT+CCID"); //Read SIM information to confirm whether the SIM is plugged
  updateSerial();
  mySerial.println("AT+CREG?"); //Check whether it has registered in the network
  updateSerial();
}

void loop()
{
  updateSerial();
}

void updateSerial()
{
  delay(500);
  while (Serial.available()) 
  {
    mySerial.write(Serial.read());//Forward what Serial received to Software Serial Port
  }
  while(mySerial.available()) 
  {
    Serial.write(mySerial.read());//Forward what Software Serial received to Serial Port
  }
}
2

If the sensor was not working before, the sensor probably is not working now.

More important; If you are making a project to do something after a crash, it must first survive the crash, or it is of no use.

3

It turns on, and blinks... But it doesn't do more than that

4

Do you have a valid 2G (network) microSIM installed (bevel out)? If the SIM800L blinks:

  • every ONE second, SIM800L is on, and searching for a network.
  • every THREE seconds, SIM800L is connected to a network and ready for transmit/receive.
  • TWICE every ONE second, SIM800L requested GPRS DATA connection is active (connected to internet).
  • SEVEN times and restarts, there is a power problem (module requires 3.4vdc - 4.4vdc at 2A)
5

Your delay is too much. You have to read lines from the modem as fast as possible. If a line longer than 64 characters comes from the modem, with this huge delay you will lose the message.
If you think you need a delay - set it 10-20milliseconds

6

My microSIM card supports up to 4G, but before removing it from the phone, I set it to 2G. And I also took the pin.
It blinks 1 time every second

7

Thank you, I will change.
I think the biggest problem is figuring out why it doesn't go beyond this "Serial.println("Initializing...");"

8

Add many more Serial.print() like the following, to find if your program stops.

#include <SoftwareSerial.h>

//Create software serial object to communicate with SIM800L
SoftwareSerial mySerial(3, 2); //SIM800L Tx & Rx is connected to Arduino #3 & #2

void setup()
{
  //Begin serial communication with Arduino and Arduino IDE (Serial Monitor)
  Serial.begin(9600);

  //Begin serial communication with Arduino and SIM800L
  mySerial.begin(9600);

  Serial.println("Initializing...");
  delay(1000);

  mySerial.println("AT"); //Once the handshake test is successful, it will back to OK
  updateSerial();
  Serial.println("AT sent");
  mySerial.println("AT+CSQ"); //Signal quality test, value range is 0-31 , 31 is the best
  updateSerial();
  Serial.println("AT+CSQ sent");
  mySerial.println("AT+CCID"); //Read SIM information to confirm whether the SIM is plugged
  updateSerial();
  Serial.println("AT+CCID sent");
  mySerial.println("AT+CREG?"); //Check whether it has registered in the network
  updateSerial();
  Serial.println("AT+CREG? sent");
}

void loop()
{
  updateSerial();
  Serial.println("void loop(){updateSerial(); sent");
}

void updateSerial()
{
  delay(500);
  while (Serial.available())
  {
    mySerial.write(Serial.read());//Forward what Serial received to Software Serial Port
   Serial.println("updateSerial() 1");
 }
  while (mySerial.available())
  {
    Serial.write(mySerial.read());//Forward what Software Serial received to Serial Port
   Serial.println("updateSerial() 2");
  }
     Serial.println("updateSerial() 3");
}

@beatrizc
Some more "inspection" items for your SM800L...

  1. Is the antenna connected? (either solder-on helical or screw-on U.FL)
  2. Simm800L needs stable operating voltage, so use an electrolytic capacitor on the +/- power of the module.
  3. Test your network connection with this project (link).
9

Your code should work.Inspect and check wire interface between your arduino, sim module and power source. Sim module are power hungry. I would suggest you to use 5 volt mobile charger or any 5 volt power source that has voltage feedback as external power source for your sim module.

10

However, I managed to get it working. The next objective is to send a message with the help of the accelerometer and gyroscope MPU6050, when it detects an accident, the SIM800L module will send a message. It seems that joining the two codes is not the most practical solution...

11

I found the problem!! I went to read the SIM800L library out of curiosity and noticed that it didn't support Mega. I tested the GSM and the MPU-6050 on the UNO and I was able to get the project working

12

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