User's Manual

LTE Module Series
EC21 Hardware Design
EC21_Hardware_Design Confidential / Released 29 / 94
The following figure shows the connection between the module and the host.
Figure 3: Sleep Mode Application via UART
 Driving thehost DTR to low level will wake up the module.
 When EC21 has URC to report, RI signal will wake up the host. Refer to Chapter 3.16 for details
about RI behavior.
 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.
AT+QCFG=“apready”commandis under development.
3.5.1.2. USB Application with USB Remote Wakeup Function
If the host supports USB suspend/resume and remote wakeup functions, the following
threepreconditionsmust be mettolet 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.
 The host’s USB bus, which is connected with the module’s USB interface, enters into suspended
state.
NOTE