If you're looking for alternatives, I hacked softwareSerial some time ago as it is notorious for bogarting the interrupts, and split it into three sub-libraries (B, C and D) that operate only with the pins on the specific ports. This leaves the other two ports available for pin change interrupts that won't work with full-on softwareSerial. You can download these from my Github page. DKWatson (David K. Watson) · GitHub