Product Info

LTE Module Series
EC21 Hardware Design
EC21_Hardware_Design
3-30
/ 105

Driving the host DTR to low level will wake up the module.

When EC21 has a URC to report, RI signal will wake up the host. Refer to Chapter 3.17 for details
about RI behaviors.

AP_READY will detect the sleep state of the host (can be configured to high level or low level
detection). Please refer to AT+QCFG="apready"* command for details.
“*” means under development.
3.4.1.2. USB Application with USB Remote Wakeup Function
If the host supports USB suspend/resume and remote wakeup functions, the following three preconditions
must be met to let the module enter into sleep mode.

Execute AT+QSCLK=1 command to enable sleep mode.

Ensure the 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 into suspended
state.
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 a URC to report, the module will send remote wake-up signals via USB bus so as to
wake up the host.
NOTE