HUAWEI ME909u-523 LTE LGA Module
Application Guide
Sleeping and Waking Up Application Scenarios
Issue 04 (2014-12-08)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
58
8.3.2
USB and Sleep
USB is an important communication channel between the module and the host.
According to the USB protocol, normally a hub or a root hub periodically sends Start
of Frame (SOF) data packages (one data package per ms using full-speed USB and
one package per 125 µs using high-speed USB). Through this mechanism, USB
always votes to stop the module from entering sleep mode.
When the USB driver provided by Huawei detects that the module and the host have
not exchanged data in 5 seconds, the USB driver will enable the port's suspend
feature, stopping SOF data packages being sent and suspending the USB controller.
This enables the USB to vote to agree the module's sleep.
NOTE
If the USB driver used is developed by users or is integrated with external application,
ensure that the USB driver supports the USB suspend features (including selective
suspend and global suspend, as defined in the USB standard.)
Before the D+/D
– connection between the host and the module disconnects, the
AT^WAKEUPCFG=1,1,
x
command (
x
is determined by the customers based on the
HUAWEI ME909u-523 LTE LGA Module AT Command Interface Specification
) must be
sent to disable the USB remote wake-up function. Otherwise, after the module is woken up,
it cannot enter sleep mode again because it keeps waking up the host over the USB.
After the D+/D
– connection between the host and the module resumes, the
AT^WAKEUPCFG =1,3,
x
command (
x
is determined by the customers based on the
HUAWEI ME909u-523 LTE LGA Module AT Command Interface Specification
) must be
sent to enable the USB remote wake-up function. Otherwise, the module cannot wake up
the host over the USB.
8.3.3
UART and Sleep
UART is an important communication channel between the module and the host. If
the host uses UART (a TTL level Interface), it can connect to the module's UART
directly. If the host uses RS232, it can connect to the module's UART through a
conversion chip such as MAX232.
NOTE
If the module is in sleep state, the host send data to module only by UART that can
’t wakeup
the module. It must be used with WAKEUP_IN pin.
8.3.4
Module Wake-up
RF periodically wakes up the module based on the DRX cycle (depending on the
actual configuration of the network system), as shown in Figure 8-5 .
Other aperiodic events include:
1. The host sends data using USB or pulls WAKEUP_IN up.
2. Changes on the network, for example, an incoming call, an incoming text
message, a signal change, a network working mode change, a network search,
an IP data package (when a dial-up network connection is set up).
3. Software system events such as a timer
4. Abnormal events, for example, an antenna drops or a SIM card becomes loose.
