Arduino NANO and GSM SIM800C no respawns with at commands

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1

Hello, I am trying to connect the Arduino NANO with SIM800C but i don't have answers with AT commands. I am using 5,4 pins of NANO to communicate with SIM800C but is not working. When I am using 8,7 pins it works great. Here is the code I am using:

#include <SoftwareSerial.h>
SoftwareSerial SIM800C(5,4);
//SoftwareSerial SIM800C(8,7);
void setup() {
  Serial.begin(9600);
  SIM800C.begin(9600);
  Serial.println("Start");
}

void loop() {
  if (Serial.available() > 0)
    SIM800C.write(Serial.read());
  if (SIM800C.available() > 0)
    Serial.write(SIM800C.read());
}

Can someone explain to me what that cause?
Pin 5 has a voltage of 2,45V and pin 4 has a voltage of 0V.
Pin 8 has a voltage 4,6V and pin 7 has a voltage of 4,6V

Thank you.

2

You probably burned pins 4 and 5 in previous experiments?

3

I have already upload new sketch with flame sensor and pins 4 and 5 works fine with 4,6V.

4

There are very few miracles in the world. If your 4,5 pins work fine, there is no reason why pins 4&5 and 8&7 work differently in the code from the main post.

5

Great, thanks for your time.

6

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