SIM800L is not working after disconnecting with PC

[rafitc99]

@salmanfaris
Sorry, leave that part
Actually I was using ("AT+CMGS=\"" +number+ "\""); this part and passing number into the funciton. This different functions all are done part of debugging.:grinning: just checking Is there any problem in string handling.

[salmanfaris]

@rafitc99 Ok, are you connecting all the ground as common in the circuit when using the LM2596 buck converter to power up the module/Arduino? and check the resistor that you are using stepdown Tx signal from Arduino to the SIM800L.!

[rafitc99]

@salmanfaris Yes. I'm providing common ground. Resistors also working.

[salmanfaris]

@rafitc99 Great, can you try this simple code that only includes the SMS sending part! if it's working fine with and without the computer connection we can look it to the other parts!

#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);


}

void loop()
{

  mySerial.println("AT"); //Once the handshake test is successful, it will back to OK
  mySerial.println("AT+CMGF=1"); // Configuring TEXT mode
  mySerial.println("AT+CMGS=\"+ZZxxxxxxxxxx\"");//change ZZ with country code and xxxxxxxxxxx with phone number to sms
  mySerial.print("SMS Test "); //text content
  updateSerial();
  mySerial.write(26);

  delay(7000);

}

[rafitc99]

@salmanfaris At that time not receiving an actual message. Receiving a blank message.

[salmanfaris]

@rafitc99 When powering SIM800L through DC-DC buck alone it's sending a message right?

[rafitc99]

@salmanfaris When connecting with PC. It will work well.

[salmanfaris]

@rafitc99 when powering with the LM2596 it's not sending message text right? but sending blank SMS right?

[rafitc99]

@salmanfaris Yes.

[salmanfaris]

Ok, then you need to check the LM2596 output current and voltage!