Usb Application With Usb Suspend/Resume And Ri Function - Quectel EC21 Series Hardware Design

The following figure shows the connection between the module and the host.
Figure 4: Sleep Mode Application with USB Remote Wakeup

Sending data to EC21 through USB will wake up the module.

When EC21 has URC to report, the module will send remote wake-up signals via USB bus so as to
wake up the host.

3.5.1.3. USB Application with USB Suspend/Resume and RI Function

If the host supports USB suspend/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 into the sleep mode.

Execute AT+QSCLK=1 command to enable sleep mode.

Ensure the DTR is held in high level or keep it open.
 The host's USB bus, which is connected with the module's USB interface, enters into suspended
state.
EC21_Hardware_Design
Module
USB_VBUS
USB_DP
USB_DM
AP_READY
GND
VDD
USB_DP
USB_DM
GPIO
GND
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EC21 Hardware Design
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