VeriFone e265, Руководство пользователя и передовые методы использования

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P
OWER
Power Modes
40
E
355/
E
265 U
SER AND
B
EST
P
RACTICES
G
UIDE
Deep Sleep
Deep sleep state is applicable only when USB interface is NOT connected to
smart device. This is the lowest possible power state with current consumption
around 12 mA, all peripherals are powered down and CPU clock runs at 32 kHz in
this state. BT/Wi-Fi data instantly wakes e355 from deep sleep without loss of
packets or data. e355 LCD display transitions to dark (appears Off) in deep sleep
state.
Power Environment
Variables
•
*PM
configuration variable is a master environmental setting for conveniently
selecting a standard power management profile. Setting this variable to one of
three settings (0 = Max Performance, 1 = Max Operational or 2 = Max
Standby) will set a combination of variables at one time including the
*POW
and
*OFF
variables below. This variable is not configured by default. For more
information, refer to Verix eVo Volume 1 Operating Systems Programmers
Manual, VPN - DOC00301.
•
*POW
configuration variable is for specifying applications idle time before
going to Active Idle state. Default is 20,000 milliseconds, and range is 20000
to 600000 milliseconds.
•
*OFF
configuration variable is for specifying applications idle time before
power off state. Default value is 10800 seconds (or 3 HRS), and range is 300
(5 minutes) to 86400 seconds (24 hours). Setting to 0 disables Sleep Mode.
It is recommended to use the default values for
*POW
and
*OFF
configuration
variables. If these are not defined the default values are used by the OS.
Power Best
Practices
In a multi-application environment every application has the responsibility to follow
best practices of power management. It is possible that system power savings are
reduced because of one misbehaving application.
Be Event Driven
•
Use
wait_event or wait_evt
calls for waiting on the required events,
and avoid using polling loops. For example, use broadcast event,
EVT_SYSTEM
, for updating battery percentage.
•
Avoid using timers as much as possible using calls
set_timer()
or
SVC_WAIT()
, because timers limit transitions to sleep state. If required, use
long timers (>20 minutes) to take advantage of sleep state.
•
Avoid continuous display updates. For example, continuous clock and time
display updates using timers will minimize the time spent in sleep state. Even
during charging, avoid continuous updates to prevent display switching
between bright and dim.