LAVA Computer MFG Inc. eSynC Product Family - Reference Manual – C03
2 Vulcan St. Toronto, ON
Tel: +1 416 674-5942
www.lavalink.com
Canada, M9W 1L2
Toll Free (US & Canada): 800 241-5282
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System Watchdog Handling
The Android system was designed to conserve battery power and memory resources of a mobile
device such as a tablet or mobile phone. The Android system limits how long a user-installed
application can run. Smartphones and tablets are consumer market devices, and running one for
an extended period of time is not the intended use case. The standard device behavior can result
in the LAVA Tablet Manager being shut down after a period of time. The LAVA product has
several safeguards to ensure LTM will continue to function.
The LTM application sends information to the eSynC on a regular basis. If the LAVA product
does not receive a message for seven minutes, the USB connection to the device is shut down for
30 seconds and then restored. Removing and restoring the USB connection forces Android to
wake up the LTM application. The 7-minute Recovery Timeout can be disabled, but this is not
recommended as it is an important feature used to ensure continuous operation of LTM.
Additional "watchdog" features include the Low-Level Detect (LLD), Low Voltage Detect
(LVD), and Stuck Level Detect (SLD) mechanisms. These features add an extra level of
protection for some rare conditions seen in a few device models.
The Low-Level Detect (LLD) monitors the device battery level. In some rare cases, the device
may refuse to start charging. This mechanism prevents the device from discharging. The
configuration commands use an "lld-” prefix. If the signal drops below the danger threshold
("lld-threshold" - "lld-offset") for three samples, then a recovery operation is started. The signal
must have been above or at the activation threshold ("lld-threshold") on a previous sample in
order to enable the detection feature. This feature is active as a default.
The Low Voltage Detect (LVD) monitors the device battery voltage. In some rare cases, the
device may refuse to start charging when using Battery Modulation. This mechanism prevents
the device from discharging. The configuration commands use an "lvd-” prefix. If the signal
drops below the danger threshold ("lvd-threshold" - "lvd-offset") for three samples, then a
recovery operation is started.
The Stuck Level Detect (SLD) feature monitors the device battery level. In some rare cases, the
device charge level gets stuck. After many hours the device recovers. This mechanism ensures
the recovery time is controlled. The configuration commands use an "sld-” prefix. If the battery
level does not change for 'x' minutes, then a recovery operation is started. This feature is disabled
as a default. This feature can be problematic if the mobile device screen timeouts are used.
