Product Info

LTE Standard Module Series
EC21 Hardware Design
EC21_Hardware_Design 40 / 120
Figure 4: Sleep Mode Application with USB Remote Wakeup
Sending data to EC21 via 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.
3.5.1.3. USB Application with USB Suspend/Resume and RI Function
If the host supports USB suspend and resume, but does not support remote wake-up function, the RI
signal is needed to wake up the host.
There are three preconditions to let the module enter 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 suspend state.
The following figure shows the connection between the module and the host.
Figure 5: Sleep Mode Application with RI