SIM900A module is responding -1 to AT command

Projects Programming
1

hello everyone, i use arduino nano and sim900a module. I connected SIM module to external power supply, i tooks only 0,05 to 0,07 Ampers. But in forums everyone says SIM is taking 2 Ampers.
When i connect my arduino and send "AT" command to board it has to respond "OK" but it is responding "-1". I tryed different baudrates for serial communication but nothing helps. Is there anyone who can help me?`
This is my code:

#include <SoftwareSerial.h>

SoftwareSerial GPRS(7, 8);         //7 = TX, 8 = RX                
void setup(){
  //delay(10000);
  GPRS.begin(1200);               // the GPRS baud rate   
  Serial.begin(19200);             // the Serial port of Arduino baud rate.
GPRS.write("AT");
delay(1000);
Serial.println(GPRS.read());

}

void loop(){

}
2

You are not terminating the command with newline, try with:

GPRS.println("AT");

And remember that the response may be more than one character, so GPRS.read() is not gonna do it.

3

Along with what the answered above suggested, also check your power supply. Which power supply are you using? Is it 5V, 2A?

4

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