LTE Module Series
EC21 Hardware Design
EC21_Hardware_Design Confidential / Released 31 / 94
The following figure shows the connection between the module and the host.
USB_VBUS
USB_DP
USB_DM
AP_READY
VDD
USB_DP
USB_DM
GPIO
Module
Host
GND
GND
RI
EINT
Figure 5: Sleep Mode Application with RI
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.
USB_VBUS
USB_DP
USB_DM
AP_READY
VDD
USB_DP
USB_DM
GPIO
Module
Host
RI
EINT
Power
Switch
GPIO
GND
GND
Figure 6: Sleep Mode Application without Suspend Function
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