SoftwareSerial on MEGA vs UNO

Other Hardware 3rd Party Boards
1

Hi guys,

Im following a tutorial on using an UNO with a GSM shield. They use SofwareSerial to enable ports 7 & 8 to communicate with the GSM SHIELD (SIM900).

Im using a MEGA and a GSM MODULE (SIM90). Originally I replaced 7 & 8 in code for 18 & 19 because thats what I normally use for Tx/Rx on the MEGA. It doesnt seem to be working. And by this I mean when I test incoming data from that shield in the loop() by using this code:

if(SIM900.available() >0)
  {   
    Serial.println("Reading SIM");
}

I get nothing logged in the monitor.

Should I be using another set of ports for the SoftwareSerial?

The thing is Im using a MODULE, not a Shield. And I've connected the Tx & Rx cables from my gsm module to the MEGA's 18 & 19 pins.

2

Software serial needs pins with PCINT - do 18/19 have that?

Hmm, seems the forum won't let me paste in what I want, you'll have to read here, scroll down to Limitations:

3

So I can use 10 & 11 I guess.

One last thing. 18 & 19 are actually hardware serials on the mega aren't they?

4

If they are, why would you use them as software serial? That's just wasting the hardware.
Yes, it appears 18/19 are Serial1.