VeriFone e355 User And Best Practices Manual page 41

Open Needed Devices Only
•
A closed device is in its lowest power consumption state, and cannot generate
unwanted events.
•
Do not keep the device open when charging. For example, contactless device
will drain battery even when external power supply is connected to e355.
•
Contactless device is special case, HW booster architecture is off of battery
supply, resulting in current draw from battery even when e355 is powered by
external power.
•
Exceptions are virtual COM devices, USB, BT and Wi-Fi.
•
Leave USB open when in use to avoid overhead in open/close before each
transaction. The device stays in optimal power saving mode and instantly
wakes from sleep. Data is serviced without loss of packets.
•
Leave BT open when in use to avoid initialization overhead during open. The
device stays in lowest power saving state—Deep Sleep during idle period.
There is instant activation or run when data is received with no lost packets.
The device maintains RF link independent of e355 power mode.
•
Leave virtual COM devices of Mobile PINpad architecture open when in use.
These devices do not consume power because physical hardware is not
controlled.
•
Leaving Wi-Fi open or closed depends on the application use case. There is
significant initialization overhead during open. The device stays in lowest
power state—Deep Sleep during idle period. There is instant activation/Run
when data is received with no lost packets. The device maintains RF link
independent of e355 power mode. The Wi-Fi interface is very "chatty" with
ARP and broadcase packets which will wake up e355 for processing and
affect e355 sleep and battery performance.
•
Wi-Fi interface is not supported in Mobile PINpad architecture. VHQ uses Wi-
Fi for e355 device management at a 60-minute heartbeat interval. It opens Wi-
Fi device to check device status and perform maintenance updates, and then
closes the device immediately.
Battery Monitoring
•
Use broadcast event EVT_SYSTEM to trigger using APIs such as
get_battery_value(), get_battery_sts(), .....
•
EVT_SYSTEM event is broadcasted to all applications when battery
percentage reading changes to 10 multiple value (i.e., when percentage
changes from 49% to 50% or from 71% to 70%) and also when external power
supply is attached or removed.
•
Do not display exact battery percentage numbers, the reason being is that
battery RC reading accuracy level is ±3%. Recommendation is to round
percentage number to nearest 10 multiple or display a "fill" battery icon.
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