Metrologic Instruments IS4921 - Manual (Page 26)

20
Power Mode Descriptions
Boot Mode
The engine is booting up.
PWRDWN Pin State: Asserted (HIGH).
Transition to Boot Mode:
• The TTL RS232 engine is turned to Boot Mode from Power Down Mode when the power is applied
AND upon reception of the nTrig or nWake signals.
• The USB engine enters Boot Mode upon completion of USB enumeration.
• The engine can turn itself to Boot Mode from Operating Mode or Idle Mode upon some internal event,
such as at the end of the software upgrade procedure.
At the end of the boot-up cycle the engine turns to the Idle Mode and de-asserts the PWRDWN pin.
Operating Mode
The engine is acquiring and processing images or running other tasks.
PWRDWN Pin State: De-asserted (LOW).
Transition to Operating Mode:
• The engine is turned to Operating Mode from Idle, Sleep, or Presentation Wakeup Modes upon the
reception of the nTrig signal.
• The engine can be turned to Operating Mode from Idle Mode (or Sleep Mode in USB version) upon the
reception of a special single-byte serial command from the host. The byte value is configurable.
• The engine is turned to Operating Mode from the Presentation Wakeup Mode upon the object detection
event.
Idle Mode
The engine is not operating, but not sleeping and is fully powered. The CPU and image sensor are in the Idle
Mode, the wakeup from which does not require the image sensor reprogramming.
PWRDWN Pin State: De-asserted (LOW).
Transition to Idle Mode:
• The engine is turned to Idle Mode from Operating Mode immediately when no tasks are running in the
engine.
• The engine is turned to Idle Mode from Sleep or Presentation Wakeup Modes upon the reception of the
nWake signal.