Quectel EC21 Series User Manual

LTE Standard Module Series
EC21_Series_Hardware_Design
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Sending data to module via USB will wake up the module.
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When module has a URC to report, the module will send remote wake-up signals via USB bus to
wake up the host.
3.5.1.3. USB Application with USB Suspend/Resume and RI Function
If the host supports USB suspend and resume, but does not support remote wake-up function, the RI
signal is needed to wake up the host.
There are three preconditions to let the module enter sleep mode.
 Execute AT+QSCLK=1 to enable sleep mode.
 Ensure DTR is held at high level or keep it open.
 The host’s USB bus, which is connected with the module’s USB interface, enters suspend state.
The following figure shows the connection between the module and the host.
Figure 5: Sleep Mode Application with RI
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Sending data to module via USB will wake up the module.
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When module has a URC to report, RI signal will wake up the host.
3.5.1.4. USB Application Without USB Suspend Function
If the host does not support USB suspend function, USB_VBUS should be disconnected via an
additional control circuit to let the module enter sleep mode.
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Execute AT+QSCLK=1 to enable sleep mode.
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Ensure the DTR is held at high level or keep it open.
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Disconnect USB_VBUS.

Quectel EC21 Series Specifications

General

Brand	Quectel
Model	EC21 Series
Category	Control Unit
Language	English