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My SIM800L doesn't respond to AT commands. The serial monitor is simply blank.

And the led blinks every 3 seconds which means it is connected to a network

I power it through an LM2596 buck down converter with 4.0 v (I've tried to power with voltages until 4.4v), From a 12v power supply.

Can you help me? (Please keep in mind that I'm an absolute beginner in this field. Thanks)

I used this wiring diagram from Last Minute Engineers. my circuit diagram

And also their code:

#include <SoftwareSerial.h> SoftwareSerial mySerial(3, 2); //SIM800L Tx & Rx is connected to Arduino #3 & #2 void setup() { Serial.begin(9600); mySerial.begin(9600); Serial.println("Initializing..."); delay(1000); mySerial.println("AT"); updateSerial(); mySerial.println("AT+CMGF=1"); updateSerial(); mySerial.println("AT+CNMI=1,2,0,0,0"); updateSerial(); } void loop() { updateSerial(); } void updateSerial() { delay(500); while (Serial.available()) { mySerial.write(Serial.read()); } while(mySerial.available()) { Serial.write(mySerial.read()); } }
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  • Check the Tx and Rx wiring carefully. Do the Arduino Tx and Rx LEDs blink? Commented Jun 30, 2023 at 4:46
  • Yes. I used the same wiring diagram with a GPS module (minus the resistors) and it worked fine Commented Jul 4, 2023 at 11:37

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