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PAGE 16
Receive Mode
If a module detects RF data while operating in Idle Mode, the module transitions into Receive
Mode to start receiving RF packets.
Figure 2.8. Reception of RF Data
After a packet is received, the module
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 module 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 module is in Receive
Mode, the serial data will be transmitted
after the module is finished receiving data
and returns to Idle Mode.
Sleep Mode
Sleep Modes enable the WCM802 / WCM900 Module to operate at minimal power consumption
when not in use. Three Sleep Mode options are available:
For the module to transition into Sleep Mode, the module must have a non-zero SM (Sleep Mode)
Parameter and one of the following must occur:
1.
2.
In Sleep Mode, the module will not transmit or receive data until the module 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 events as shown in the table below.
Table 2.1. Summary of Sleep Mode Configurations
Sleep Mode
Setting
Pin Sleep
(SM = 1)
Serial Port Sleep
(SM = 2)
Cyclic Sleep
(SM = 3-8)
For more information about Sleep Modes, refer to the individual commands listed in "Related Commands"
column of the table. SM Command is the best starting point for implementing Sleep Mode configurations.
20 JUN 2005
• Pin Sleep (Host Controlled)
• Serial Port Sleep (Wake on Serial Port activity)
• Cyclic Sleep (Wake on RF activity)
The module is idle (no data transmission or reception) for a user-defined period of time [See
ST (Time before Sleep) Command].
SLEEP (pin 2) is asserted (only for Pin Sleep option).
Transition into
Sleep Mode
Microcontroller can shut down and wake
modules by asserting (high) SLEEP (pin 2).
Note: The module will complete a
transmission or reception even if Pin Sleep
is activated.
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.
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).
Transition out of
Related
Sleep Mode
Commands
De-assert (low)
SM
SLEEP (pin 2).
When serial byte is
received on the DI pin
SM, ST
(pin 4).
After the cyclic sleep
time interval elapses.
SM, ST, HT,
Note: Module can be
LH, PW
forced into Idle Mode
if PW (Pin Wake-up)
Command is issued.
WCM802/900
Typical Power
Consumption
26 µA
1 mA
76 µA
when sleeping
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