System modes

Automatic mode (threading enabled)

SYSTEM_MODE(AUTOMATIC);
#ifndef SYSTEM_VERSION_v620
SYSTEM_THREAD(ENABLED); // System thread defaults to on in 6.2.0 and later and this line is not required
#endif

void setup() {
  // This is called even before being cloud connected
}

void loop() {
  // This is too
}

When also using SYSTEM_THREAD(ENABLED), the following are true even in AUTOMATIC mode:

• When the device starts up, it automatically tries to connect to Wi-Fi or Cellular and the Particle Device Cloud.
• Messages to and from the Cloud are handled from a separate thread and are mostly unaffected by operations in loop.
• If you block loop() from returning you can still impact the following:
  • Function calls
  • Variable retrieval
  • Serial events

Using SYSTEM_THREAD(ENABLED) is recommended. With Device OS 6.2.0 and later, system thread is always enabled. For additional information, see non-threaded system mode.