B&B Electronics ZXT9-MB2A-KIT - Manual - Manual (Page 62)

Document Number: ZXTxRM-5110m
Page
62
• If the host does not allow the modem to transmit data out from the output buffer
because of being held off by hardware or software flow control.
6.3.5 Sleep Mode
Sleep Modes enable the module to enter states of low-power consumption when not in
use. Three software Sleep Modes are supported:
• Pin Sleep (Host Controlled)
• Serial Port Sleep (Wake on Serial Port activity)
• Cyclic Sleep (Wake on RF activity)
In order to enter Sleep Mode, one of the following conditions must be met (in addition to
the modem having a non-zero SM parameter value):
• The modem is idle (no data transmission or reception) for the amount of time defined
by the ST (Time before Sleep) parameter. [NOTE: ST is only active when SM = 4-5.]
• SLEEP (DTR) is asserted (only for the 'Pin Sleep' option).
When 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.
The SM (Sleep Mode) command is central to setting all Sleep Mode configurations. By
default, Sleep Modes are disabled (SM = 0) and the modem remains in Idle/Receive
Mode. When in this state, the modem is constantly ready to respond to serial or RF
activity.
Refer to the 'Hardware Sleep' section of the 'Shutdown Mode' section to enable the
modem's lowest power-consuming state.
6.3.5.1 Pin Sleep Mode
Pin Sleep (SM = 1)
• Pin/Host-controlled
This mode is voltage level activated. When DTR/SLP is asserted, the
modem will finish any transmitting or receiving activity; enter Idle Mode;
then enter a state of sleep. When in Pin Sleep Mode, the modem will
not respond to serial or RF activity.
After enabling Pin Sleep, the SLEEP pin controls whether the modem is
active or sleeping. When SLEEP is de-asserted, the modem is fully
operational. When SLEEP is asserted, the modem transitions to Sleep
Mode and remains in its lowest power-consuming state until the pin is
de-asserted.
Note:
The modem will complete a transmission or reception before
activating Pin Sleep.
6.3.5.2 Serial Port Sleep Mode
Serial Port Sleep (SM = 2)
• Wake on serial port activity
Serial Port Sleep is a Sleep Mode in which the modem runs in a low
power state until serial data is detected on the modem.