Softwareserial - use any digital pin? Even non-PWM?

Using Arduino Programming Questions
1

The softwareserial library saids any digital pin can be used:

Do they really mean ANY digital pin, or only the PWM capable digital pins? How does that work - that the Arduino can do serial comms over a non-PWM pin? That seems too good to be true?

2

What has PWM got to do with it?

Mark

3

SoftwareSerial uses a pin change interrupt to detect the leading edge of a character. It will work on any pin that has a pin change interrupt capability, which is all of them I believe. The transmit side just has to be a digital pin, any digital pin.

Maybe you're thinking of AltSoftSerial? It uses PWM and only works with specific pins.

arusr:
How does that work - that the Arduino can do serial comms over a non-PWM pin? That seems too good to be true?

SoftwareSerial disables interrupts for the entire time it takes to send or receive a character. This is how it maintains the proper timing. The downside is that while its sending or receiving your Arduino is basically a UART with few cycles to spare for other processing.