User's Manual

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.
Figure 5: Sleep Mode Application with RI
 Sending data to EC21through USB will wake up the module.
 When EC21has 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=1command 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