XStream-PKG-R™ RS-232/485 RF Modem – Product Manual v5.x00
3 .2 .3 . Re ce ive M ode
I f t he m odem det ect s RF dat a w hile in I dle Mode, t he m odem t r ansit ions int o Receive Mode to
r eceiv e RF pack et s. Once a pack et is receiv ed, t he m odem check s t he CRC t o ensur e t hat t he
dat a w as t r ansm it t ed w it hout er ror . I f t he CRC dat a bit s on t he incom ing pack et ar e inv alid, t he
packet is discar ded. I f t he CRC is v alid, t he pack et proceeds t o t he DO Buffer .
The m odem ret ur ns to I dle Mode w hen v alid RF dat a is no longer det ect ed or aft er an er ror is
det ect ed in t he r eceiv ed RF dat a.
Figure 3.6.
Data Reception Sequence
Refer to the Addressing section (p41) of the
RF Communication Modes chapter for more information
regarding address recognition.
3 .2 .4 . Sle e p M ode s
Sleep Modes enable t he XSt r eam Modem to oper at e at m inim al pow er consum pt ion w hen not in
use. Thr ee Sleep Mode opt ions are av ailable:
•
Pin Sle e p
( Host Cont rolled)
•
Se r ia l Por t Sle e p
( Wak e on Ser ial Por t act iv it y )
•
Cy clic Sle e p
( Wak e on RF activ it y )
For t he m odem t o t r ansit ion int o Sleep Mode, t he m odem m ust hav e a non- zer o SM ( Sleep Mode)
par am et er and one of t he follow ing m ust occur :
1.
The m odem is idle ( no dat a transm ission or r ecept ion) for a user - defined per iod of t im e
( Refer t o t he ST ( Tim e before Sleep) com m and) .
2.
SLEEP pin is asser t ed ( only for Pin Sleep opt ion) .
I n Sleep Mode, t he m odem w ill not t r ansm it or receive dat a unt il t he m odem fir st t r ansit ions t o
I dle Mode. All Sleep Modes are enabled and disabled using SM Com m and. Tr ansit ions into and
out of Sleep Modes are tr iggered by v ar ious m echanism s as show n in t he t able below .
Table 3.2.
Summary of Sleep Mode Configurations
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 modem 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
For more information about Sleep Modes, refer to the individual commands listed in “Related Commands”
column of the table. The SM command is central to all Sleep Mode configurations.
Not e: I f ser ial dat a ex ist s in the DI buffer w hile t he m odem is in
Receiv e Mode, t he UART dat a w ill be tr ansm it t ed aft er t he m odem is
finished r eceiv ing t he RF dat a and has r et ur ned to I dle Mode.
© 2014 Digi International Inc.
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