B&B Electronics ZXT9-MB2A-KIT - Manual - Manual (Page 63)

Document Number: ZXTxRM-5110m
Page
63
The period of time the modem sleeps is determined by ST (Time before
Sleep) Command. Once a character is received through the input, the
modem returns to Idle Mode and is fully operational.
6.3.5.3 Cycle Sleep Mode
Cyclic Sleep (SM = 4-8)
Cyclic Sleep Modes allow modems to periodically wake and check for
RF data. The modem wakes according to the times designated by the
Cyclic sleep settings. If the modem detects a wake-up initializer during
the time it is awake, the modem synchronizes with the transmitting
modem and receives data after the wake-up initializer runs its duration.
Otherwise, the modem returns to Sleep Mode and continues to cycle in
and out of activity until a wake-up initializer is detected.
While the modem is in Cyclic Sleep Mode, CTS is de-asserted (high) to
indicate that data should not be sent to the modem. When the modem
awakens to listen for data, CTS is asserted and any data received on
the modem input is transmitted.
The modem remains in Sleep Mode for a user-defined period of time
ranging from 0.5 seconds to 16 seconds (SM parameters 4 through 8).
After this interval of time, the modem returns to Idle Mode and listens for
a valid data packet for 100 ms. If the modem does not detect valid data
(on any frequency), the modem returns to Sleep Mode. If valid data is
detected, the modem transitions into Receive Mode and receives the
incoming RF packets. The modem then returns to Sleep Mode after a
period of inactivity determined by the ST "Time before Sleep"
parameter.
The modem can also be configured to wake from cyclic sleep when
DTR/SLP is de-asserted. To configure a modem to operate in this
manner, PW (Pin Wake-up) Command must be issued. Once the
SLEEP pin is de-asserted, the modem is forced into Idle Mode and can
begin transmitting or receiving data. It remains active until data is no
longer detected for the period of time specified by the ST Command, at
which point it resumes its low-power cyclic state.
Cyclic Scanning . Each RF transmission consists of an RF Initializer
and payload. The RF initializer contains initialization information and all
receiving modems must wake during the wake-up initial-izer portion of
data transmission in order to be synchronized with the transmitting
modem and receive the data.
6.3.6 Command Mode
To modify or read RF modem parameters, the modem must first enter into Command
Mode (state in which incoming characters are interpreted as commands). Two command
types are supported: AT Commands and Binary Commands.
For modified parameter values to persist in the modem registry, changes must be saved
to non-volatile memory using the WR (Write) command. Otherwise, parameters are
restored to previously saved values when the modem is powered off and then on again.