Product manual
XStream‐PKG‐R™RS‐232/485RFModem–ProductManualv4.2B
©2005MaxStream,Inc.Confidential&Proprietary 16
3.2.3. Receive Mode
If a modem detects RF data while operating in Idle Mode, the modem transitions into Receive
Mode to start receiving RF packets.
Figure3.7. ReceptionofRFDataÆ
After a packet is received, the modem
checks the CRC (cyclic redundancy check)
to ensure that the data was transmitted
without error. If the CRC data bits on the
incoming packet are invalid, the packet is
discarded. If the CRC is valid, the packet
proceeds to the DO Buffer.
The modem returns to Idle Mode after
valid RF data is no longer detected or after
an error is detected in the received RF
data. If serial data is stored in the DI
buffer while the modem is in Receive
Mode, the serial data will be transmitted
after the modem is finished receiving data
and returns to Idle Mode.
3.2.4. Sleep Mode
Sleep Modes enable the XStream Modem to operate at minimal power consumption when not in
use. Three Sleep Mode options are available:
• Pin Sleep (Host Controlled)
• Serial Port Sleep (Wake on Serial Port activity)
• Cyclic Sleep (Wake on RF activity)
For the modem to transition into Sleep Mode, the modem must have a non-zero SM (Sleep Mode)
Parameter and one of the following must occur:
1. The modem is idle (no data transmission or reception) for a user-defined period of time
[Refer to ST (Time before Sleep) Command].
2. SLEEP pin is asserted (only for Pin Sleep option).
In Sleep Mode, the modem will not transmit or receive data until the modem first transitions to
Idle Mode. All Sleep Modes are enabled and disabled using SM Command. Transitions into and
out of Sleep Modes are triggered by various mechanisms as shown in the table below.
Table3.2. SummaryofSleepModeConfigurations
Sleep Mode
Setting
Transition into
Sleep Mode
Transition out of
Sleep Mode
Related
Commands
Typical Power
Consumption
Pin Sleep
(SM = 1)
A microcontroller can shut down and wake
modems by asserting (high) SLEEP pin.
Note: The module will complete a
transmission or reception before activating
Pin Sleep.
De-assert SLEEP pin. SM 6 mA
Serial Port Sleep
(SM = 2)
Automatic transition to Sleep Mode occurs
after a user-defined period of inactivity (no
transmitting or receiving of data). The
period of activity is defined using the ST
(Time before Sleep) Command.
When serial byte is
received on the DI pin.
SM, ST 25 mA
Cyclic Sleep
(SM = 3-8)
Automatic transition to Sleep Mode occurs
in cycles as defined by the SM (Sleep
Mode) Command.
Note: The cyclic sleep time interval must be
shorter than the “Wake-up Initializer Timer”
(set by LH Command).
After the cyclic sleep
time interval elapses.
Note: Modem can be
forced into Idle Mode
if PW (Pin Wake-up)
Command is issued.
SM, ST, HT, LH,
PW
6 mA
when sleeping
FormoreinformationaboutSleepModes,refertotheindividualcommandslistedin“RelatedCommands”
columnofthetable.SMCommandisthebeststartingpointforimplementingsleepmodeconfigurations.