SIM800L is not working after disconnecting with PC

[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!

[rafitc99]

Thank-you @salmanfaris
It's solved.
Actually, It was my mistake. I didn't add a proper reset for MCU.