# SIM800L - No response while sending AT commands

I'm new to this arduino world. I'm trying to communicate with my arduino nano and SIM800L. I read few things in the internet and found a basic code. I tried copying it and tried to work it out, but I'm not getting the response as expected. I'm posting the code which I tried:

#include <SoftwareSerial.h>

SoftwareSerial mySerial(11, 10); // RX, TX

void setup()
{
// Open serial communication
Serial.begin(9600);

// set the data rate for the SoftwareSerial port
mySerial.begin(9600);

delay(1000);
Serial.println("Testing SIM800L module");
Serial.println();
Serial.print("Sizeof(mySerial) = "); Serial.println(sizeof(mySerial));
Serial.println();

}

void loop() // run over and over
{

if( mySerial.available() )
{
Serial.print(c);
}

if(Serial.available())
{

Serial.println("Serial available");
Serial.println(Arsp);
mySerial.println(Arsp);
Serial.println("Serial available end");
}

}


I tried to send AT command and the output I received was:

Testing SIM800L module

Sizeof(mySerial) = 31

Serial available
AT


Serial available end

I don't get OK, which I should receive, it's returning empty.

I don't understand what's going wrong. Can someone help me with it?

• Have you checked the baudrate of SIM800? – Abel Tom Oct 5 '17 at 9:14
• Yea, it's 9600. – Electronic Brat Oct 5 '17 at 9:20
• @AbelTom: I've updated my question. Take a look. – Electronic Brat Oct 5 '17 at 9:22
• How are you resetting the SIM800L? A link to the SIM800L module that you're using may help, since there are many available. – Steve G Oct 5 '17 at 9:31
• @AbelTom As far as I remember sim800 doesn't work @ 5 V. It is some small range around 4V – MaNyYaCk Oct 5 '17 at 13:24

Use #include <string.h> at the start since you can't use any string without the initialisation. Otherwise, your code should be working.