Usb Application Without Usb Suspend Function - Quectel EC21 Series Hardware Design

The following figure shows the connection between the module and the host.

Sending data to EC21 through USB will wake up the module.

When EC21 has 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, you should disconnect USB_VBUS with additional
control circuit to let the module enter into sleep mode.

Execute AT+QSCLK=1 command to enable sleep mode.

Ensure the DTR is held in high level or keep it open.

Disconnect USB_VBUS.
The following figure shows the connection between the module and the host.
Figure 6: Sleep Mode Application without Suspend Function
EC21_Hardware_Design
Module
USB_VBUS
USB_DP
USB_DM
AP_READY
RI
GND
Figure 5: Sleep Mode Application with RI
Module
USB_VBUS
USB_DP
USB_DM
RI
AP_READY
GND
Confidential / Released
Host
VDD
USB_DP
USB_DM
GPIO
EINT
GND
Host
GPIO
Power
VDD
Switch
USB_DP
USB_DM
EINT
GPIO
GND
LTE Module Series
EC21 Hardware Design
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