I get the same error when using the SoftwareSerial library. More specific, it is a known limitation that you cannot use SoftwareSerial.h and PinChangeInt.h together without altering one or another.
Let me give you an example, I was in the same case as you are now, I wanted to use an RF ID reader (125 kHz - RDM6300) on a software serial pin, in my case was A2 (don't ask why, this was the only input pin that I have on an UNO, it is stuffed with keyboard, display, motor actuator for door opening, button for manual door opening, ringer button and NRF24 - this is my all in one entrance sensor ). So, what you have to do:
pin A2 is on Port C
you have to disable in the SoftwareSerial.h the other intrerupts, except the one associated to PortC, that would be - PCINT1 is for Port C :
PCINT0 is for Port B
PCINT2 is for Port D
PCINT3 - it is not the case of 328P so you can leave it uncommented
so in SoftwareSerial.h comment the following for PCINT0 and 2:
#if defined(PCINT0_vect)
ISR(PCINT0_vect)
{
ReceiveOnlySoftwareSerial::handle_interrupt();
}
#endif
The other thing that you have to do now is to tell PinChangeInt.h that you use Port C for other purpose. To do this, in MyGateway.cpp, ahead of the #include "utility/PinChangeInt.h" you should include the following:
#define NO_PORTC_PINCHANGES
Save, upload, enjoy... And don't forget to modify back what you altered.
This assumes that you don't use intrerupts on pins...
