Specifications

Host/Module Interfaces
Rev 2.0 Apr.10 Proprietary and Confidential 57
• Enumeration of the module as a set of /dev/ttyUSBn devices for Linux
systems with the Sierra Wireless driver installed
• USB-compliant transceivers
USB handshaking
Note: If you are using Sierra Wireless drivers, you can skip this section—it is intended for
developers who are creating their own USB drivers.
The host must act as a USB host device to interface with the module.
The module uses the USB standard Suspend and Resume functions (described
further) to control the sleep and wakeup states. For detailed specifications of
Resume and Suspend, refer to Universal Serial Bus Specification, Rev 2.0.
Suspending
The module supports USB Suspend mode.
When the module enters suspend mode, it shuts down the USB clock to save
power.
While in the suspend state:
• The module provides power to the D+/- interface to signal its current state to
the host device.
• The host must maintain the VCC_3V3 voltage (VCC_3V8 for MC8201)
Refer to Universal Serial Bus Specification, Rev 2.0 for critical timing parameters
for the suspend state.
Resume
USB activity may be resumed by either the USB host or by the module.
If the host initiates USB activity:
1. The USB transceiver detects the change in bus activity and triggers the
USB_RESUME interrupt to the module's processor.
2. The module then enables its USB clock and responds to the host.
If the module initiates USB communication (Remote Wakeup):
1. The module enables its USB clock.
2. The module enables the USB transceiver.
3. The module sends the resume signal for at least 20 ms.
Refer to Universal Serial Bus Specification, Rev 2.0 for critical timing parameters
for the resume state.