Device Operation; Power Management - Enfora Spider AT 3000 User Manual

7 Device Operation

7.1 Power Management

The Spider AT 3000 has been designed to minimize power consumption to maximize battery life. The
device has different power states to optimize system-level power consumption. The Spider AT 3000 uses a
low-power microcontroller to control the power states. Between position reports, the microcontroller
enters an idle state until the next scheduled position check. When it is time to check for a new position, the
microcontroller can use the motion sensor and GPS receiver to determine if the device has moved. If the
device has not moved, the microcontroller can quickly return to the idle state without generating a position
report.
The power states are:
Microcontroller idle – This is the lowest power state. The microcontroller is powered on but the proc-
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essor is idle waiting for a timer expiry based upon the next scheduled position check.
Motion sensor – The motion sensor is used as an ultra-low power detection of movement. This state
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only lasts a few seconds while the motion sensor is measured to detect movement. If no motion is
detected, then the device may return to the idle state. If motion is detected, then the GPS receiver is
turned on.
GPS receiver – The microcontroller and GPS receiver are powered. The GPS receiver acquires the
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GPS satellites and determines the current position. A geofence may be used to determine if the new
position is a significant (configurable) distance from the previous position.. If the device is still
located with the geofence boundary, then the device may return to the idle state.
GSM modem – The GSM modem is turned on only if a position report is needed. The modem reg-
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isters on the GSM network and sends the position report to the remote server. After transmitting the
position report, the modem remains registered on the GSM network for a period of time and listens
for new over-the-air configuration messages from the server.
External power does not guarantee that the device will be in "tracking" mode where
the modem and GPS receiver are always powered on. Now, the device will be in
tracking mode if the next report is scheduled in <5 minutes based upon the CFGIP and
CFGOP parameters.
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