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HUAWEI ME909u-521 LTE LGA Module
Application Guide
Sleeping and Waking Up Application Scenarios
Issue 01 (2013-07-05)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
57
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.)
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.
8.3.5 Host Woken up by Module
Wake-up Source
A wake-up source is a module event that can wake up the host, for example, an
incoming voice call, a text message, data (PPP data, TCP/UDP data from the
network), and unsolicited messages.
Remotely Waking up the Host Using USB
When the host is in sleep mode and the USB controller is in suspended mode, if the
module needs to send data to the host (for example, a wake-up source has arrived),
the module sends a remote wake-up signal that lasts 3 ms to inform the host to start
USB resume (as shown in Figure 8-7 ). To complete the procedure, the following
conditions must be met:
1. The USB controller on the host supports USB remote wake-up and can wake up
the host.