PAGE
30
20
JUN
2005
WCM802/900
SM (Sleep Mode) Command
<Sleep Mode (Low Power)> SM Command is used
to adjust Sleep Mode settings. By default, Sleep
Mode is disabled and the module remains
continually active. SM Command allows the
module to run in a lower-power state and be
configured in one of eight settings.
Cyclic Sleep settings wake the module after the
amount of time designated by SM Command. If
the module detects a wake-up initializer during
the time it is awake, it will synchronize with the
transmitter and start receiving data after the
wake-up initializer runs its duration. Otherwise, it
returns to Sleep Mode and continue to cycle in
and out of inactivity until the Wake-up Initializer
is detected. If a Cyclic Sleep setting is chosen,
the ST, LH and HT parameters must also be set
as described in the “Sleep Mode” section of this
manual.
Pin Sleep (SM = 1)
Pin Sleep requires the least amount of power. In
order to achieve this state, SLEEP pin must be
asserted (high). The module remains in Pin Sleep
until the SLEEP pin is de-asserted.
After enabling Pin Sleep, the SLEEP pin controls
whether the WCM802 / WCM900 Module is active
or in Sleep Mode. When SLEEP is de-asserted (low), the module is fully operational. When SLEEP
is asserted (high), the module transitions to Sleep Mode and remains in its lowest power-
consuming state until the SLEEP pin is de-asserted. SLEEP is only active if the module is setup to
operate in this mode; otherwise the pin is ignored.
Once in Pin Sleep Mode,
is de-asserted (high), indicating that data should not be sent to the
module. The PWR pin is also de-asserted (low) when the module is in Pin Sleep Mode.
Serial Port Sleep (SM = 2)
Serial Port Sleep is a Sleep Mode in which the WCM802 / WCM900 Module runs in a low power
state until serial data is detected on the DI pin.
When Serial Port Sleep is enabled, the module goes into Sleep Mode after a user-defined period
of inactivity (no transmitting or receiving of data). This period of time is determined by ST (Time
before Sleep) Command. Once a character is received through the DI pin, the module returns to
Idle Mode and is fully operational.
Cyclic Sleep (SM = 3-8)
Cyclic Sleep is the Sleep Mode in which the WCM802 / WCM900 Module enters into a low-power
state and awakens periodically to determine if any transmissions are being sent.
When Cyclic Sleep settings are enabled, the WCM802 / WCM900 Module goes into Sleep Mode
after a user-defined period of inactivity (no transmission or reception on the RF channel). The
user-defined period is determined by ST (Time before Sleep) Command.
While the module is in Cyclic Sleep Mode,
is de-asserted (high) to indicate that data should
not be sent to the module during this time. When the module awakens to listen for data,
is
asserted and any data received on the DI Pin is transmitted. The PWR pin is also de-asserted
(low) when the module is in Cyclic Sleep Mode.
AT Command: ATSM
Binary Command: 0x01
Parameter Range: 0 – 8
Parameter
Value
Configuration
0 Disabled
1 Pin
Sleep
2
Serial Port Sleep
3
Cyclic 0.5 second sleep
(Module wakes every 0.5
seconds)
4
Cyclic 1.0 second sleep
5
Cyclic 2.0 second sleep
6
Cyclic 4.0 second sleep
7
Cyclic 8.0 second sleep
8
Cyclic 16.0 second sleep
Default Parameter Value: 0
Number of bytes returned: 1
Related Commands:
For Pin Sleep – PC (Power-up Mode), PW (Pin
Wake-up)
For Serial Port Sleep – ST (Time before Sleep)
For Cyclic Sleep – ST (Time before Sleep), LH
(Wake-up Initializer Timer), HT (Time Before
Wake-up Initializer), PW (Pin Wake-up)