There is no multi-process, nor multi-threading, support on the Arduino. You can do something close to multiple threads with some software though.
You want to look at Protothreads:
Protothreads are extremely lightweight stackless threads designed for severely memory constrained systems, such as small embedded systems or wireless sensor network nodes. Protothreads provide linear code execution for event-driven systems implemented in C. Protothreads can be used with or without an underlying operating system to provide blocking event-handlers. Protothreads provide sequential flow of control without complex state machines or full multi-threading.
Of course, there is an Arduino example here with example code. This SO question might be useful, too.
ArduinoThread is a good one too.
Answer from sachleen on Stack ExchangeVideos
There is no multi-process, nor multi-threading, support on the Arduino. You can do something close to multiple threads with some software though.
You want to look at Protothreads:
Protothreads are extremely lightweight stackless threads designed for severely memory constrained systems, such as small embedded systems or wireless sensor network nodes. Protothreads provide linear code execution for event-driven systems implemented in C. Protothreads can be used with or without an underlying operating system to provide blocking event-handlers. Protothreads provide sequential flow of control without complex state machines or full multi-threading.
Of course, there is an Arduino example here with example code. This SO question might be useful, too.
ArduinoThread is a good one too.
AVR based Arduino's do not support (hardware) threading, I am unfamiliar with the ARM based Arduino's. One way around this limitation is the use of interrupts, especially timed interrupts. You can program a timer to interrupt the main routine every so many microseconds, to run a specific other routine.
https://www.arduino.cc/reference/en/language/functions/interrupts/interrupts/
In short: NO. But you may give it a shot at: http://www.kwartzlab.ca/2010/09/arduino-multi-threading-librar/
(Archived version: https://web.archive.org/web/20160505034337/http://www.kwartzlab.ca/2010/09/arduino-multi-threading-librar
Github: https://github.com/jlamothe/mthread
Not yet, but I always use this Library with big projects: https://github.com/ivanseidel/ArduinoThread
I place the callback within a Timer interrupt, and voilá! You have pseudo-threads running on the Arduino...