Murata Electronics North America DNT500FP Manual Do Utilizador
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©2008 by RF Monolithics, Inc.
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DNT900 - 11/05/08
•
If a remote is linking for the first time or if its last attempt to acquire and synchronize was unsuc-
cessful, it will send a registration request to the base, allowing it to announce its presence to the
host. Otherwise, in order to conserve battery life, a sleeping remote will not register each time it
reacquires link with its base on successive wakeups.
host. Otherwise, in order to conserve battery life, a sleeping remote will not register each time it
reacquires link with its base on successive wakeups.
•
After a remote has received an acknowledgement for its I/O report (assuming it is successful), a
WakeResponse Time
timer is started before the remote goes back to sleep. This allows the base
host time to send a message to the remote. Note that the only notification that the base host ap-
plication has that a remote is awake is its report packet. In order to send it data, the base host
must ensure that the message is transmitted and received before the remote's WakeRespon-
seTime
plication has that a remote is awake is its report packet. In order to send it data, the base host
must ensure that the message is transmitted and received before the remote's WakeRespon-
seTime
window elapses. If this function is not needed, the WakeResponse Time can be set to
zero to disabled it.
The lease renewal mechanism is not supported for sleeping remotes. In order to successfully use sleep-
ing remotes, the user must ensure that the system is configured for CSMA mode and that leases are
disabled. If these settings are not used, there is no guarantee that the remotes will be able to communi-
cate reliably. Because leases are not supported, there is no built-in mechanism for the base to detect or
announce to its host if a remote stops making its I/O reports, is powered down, or otherwise leaves the
network.
ing remotes, the user must ensure that the system is configured for CSMA mode and that leases are
disabled. If these settings are not used, there is no guarantee that the remotes will be able to communi-
cate reliably. Because leases are not supported, there is no built-in mechanism for the base to detect or
announce to its host if a remote stops making its I/O reports, is powered down, or otherwise leaves the
network.
To summarize, while a remote is awake, the following list of condition checks are used to determine if and
when it is allowed to go back to sleep:
when it is allowed to go back to sleep:
•
If the remote is linking for the first time or was unsuccessful linking on its last attempt, it will re-
main awake to record the beacon system parameter list.
•
At wakeup, the WakeLinkTimeout timer is started. If the remote is unable to acquire link before
this elapses, it goes back to sleep.
•
If the remote receives an acknowledgement for a data packet it has sent (typically an Event
packet, but in theory could be any other type of message), it starts or resets the WakeRespon-
seTime
seTime
timer to remain awake.
•
So long as a GPIO for which edge triggered I/O reporting is enabled remains in its asserted state,
the remote will remain awake.
•
The remote will remain awake while it still has any ARQ attempts left for a queued transmit
packet of any type.
•
The remote will remain awake while it is has serial characters in its buffer left to transmit to its lo-
cal host, plus whatever time is required for the last transmitted character to clear the RXD pin.
Sleep functions are controlled by the following registers (see Section 4.2):
•
SleepMode
- enables/disables sleep mode.
•
WakeResponse Time
- sets the amount of time that a remote will wait for a
response after sending an I/O report.
•
WakeLinkTimeout
- sets the maximum time that a remote will spend trying
to acquire it base before giving up.