SoftwareSerial not detecting

[takashitee]

Hi, guys, I am doing my school project (GPS Tracking + Fall Detection). I tried to use software serial to connect my SIM800l with my Arduino Nano but somehow the serial monitor are not detecting my pins or something

#include <SoftwareSerial.h>

SoftwareSerial mySerial(3, 2);

void setup()
{
  Serial.begin(9600);
  mySerial.begin(9600);

  Serial.println("Initializing...");
  delay(1000);

  sendATCommand("AT");
  sendATCommand("AT+CMGF=1");
  sendATCommand("AT+CMGS=\"+ZZxxxxxxxxxx\""); // Enter your phone number here (prefix country code)
  sendATCommand("Hello from DIY Projects Lab"); // Enter your message here
  mySerial.write(26);
}

void loop()
{
}

void sendATCommand(const char* command)
{
  mySerial.println(command);
  delay(500);

  while (mySerial.available())
  {
    Serial.write(mySerial.read());
  }
  Serial.println();
}

In here, I used pin D3 and D2 as RX and TX, I also inserted the pin correctly between my SIM800l and Nano. But the Serial monitor will just prompt 'Initializing' and 4 empty row.

Then, I thought I will just try to use the hardware serial, so I connected the RX and TX of SIM800l to the TX and RX of Arduino then I change my code

void setup()
{
  Serial.begin(9600);
  Serial.begin(9600);

  Serial.println("Initializing...");
  delay(1000);

  sendATCommand("AT");
  sendATCommand("AT+CMGF=1");
  sendATCommand("AT+CMGS=\"+ZZxxxxxxxxxx\""); // Enter your phone number here (prefix country code)
  sendATCommand("Hello from DIY Projects Lab"); // Enter your message here
  Serial.write(26);
}

void loop()
{
}

void sendATCommand(const char* command)
{
  Serial.println(command);
  delay(500);

  while (Serial.available())
  {
    Serial.write(Serial.read());
  }
  Serial.println();
}

Now, the Serial monitor prompt 4 lines which is

14:50:15.957 -> Initializing...
14:50:16.934 -> AT
14:50:17.438 ->
14:50:17.438 -> AT+CMGF=1
14:50:17.949 ->
14:50:17.949 -> AT+CMGS="+ZZxxxxxxxxxx"
14:50:18.488 ->
14:50:18.488 -> Hello from DIY Projects Lab

Blockquote

I thought I am supposed to get 'OK' as reply and other print command at the bottom but no , just these.... I tried with GPS module, it is the same problem, it cannot detect any wiring when I use software serial or sometimes the inputed pin are different with physical pin but somehow work...

[ec2021]

Hi @takashitee,

you may have a look at this page

https://wolles-elektronikkiste.de/en/sim800l-module

check your wiring and try the examples provided there.

It looks as if you don't get any response from the SIM800 board. The most simple reason could be that you did not connect TX - RX, RX -TX, but RX-RX , TX-TX...

And check this information on usable pins

SoftwareSerial Library | Arduino Documentation

With a Nano your pins should work but you may try others to be sure.