As bits arrive, Arduino’s poor little processor must sample and process each of 4 incoming bits within 26 microseconds or else lose them forever. Imagine four serial devices connected to an Arduino, each transmitting at 38,400 baud. However, handling asynchronously received data from two, three, or four or more serial devices turns out to be an extremely difficult, if not intractable problem. There has been considerable support for an library that would allow multiple soft serial devices. The interrupt handler at these rate becomes so lengthy that timer tick interrupts can be starved, causing millis() to stop working during receives.
**Be circumspect about using 3 baud though. *But see below for an important caveat on multiple instances. (New) It supports an end() method as a complement to begin().
(New) It runs on the Teensy and Teensy++. It uses direct port I/O for faster and more precise operation. Higher baud rates have been tuned for better accuracy. It provides a boolean overflow() method to detect buffer overflow. It supports a much wider range of baud rates.**. It supports multiple simultaneous soft serial devices.*. It extends support to all Arduino pins 0-19 (0-21 on Arduino Mini), not just 0-13. It implements circular buffering scheme to make RX processing more efficient. It inherits from built-in class Print, eliminating some 4-600 bytes of duplicate code. NewSoftSerial offers a number of improvements over SoftwareSerial: Using interrupt-driven RX, your program fills its buffer behind the scenes while processing previously received data. This is where AFSoftSerial’s (and NewSoftSerial‘s) interrupt architecture is a godsend. Your program is too busy trying to keep up with NMEA characters as they arrive to actually spend time assembling them into something meaningful. This makes it nearly impossible, for example, to use SoftwareSerial to receive GPS data and parse it into a usable form. Without interrupts, your program’s design is considerably restricted, as it must continually poll the serial port at very short, regular intervals. It’s the direct descendant of ladyada’s AFSoftSerial, which introduced interrupt-driven receives – a dramatic improvement over the polling required by the native SoftwareSerial. NewSoftSerial is the latest of three Arduino libraries providing “soft” serial port support. To port your code to 1.0, simply change all NewSoftSerial references to SoftwareSerial. This means that if you have 1.0 or later, you should not download this library. News: NewSoftSerial is in the core! Starting with Arduino 1.0 (December, 2011), NewSoftSerial has replaced the old SoftwareSerial library as the officially supported software serial library. A New Software Serial Library for Arduino
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