User's Manual

PH8/PH8-P Hardware Interface Overview
3.3 USB Interface
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PH8_PH8-P_HD_v02.000 Page 22 of 46 2011-10-21
Confidential / Released
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3.3 USB Interface
PH8/PH8-P supports a USB 2.0 High Speed (480Mbit/s) device interface that is Full Speed
(12Mbit/s) compliant. The USB interface is primarily intended for use as command and data
interface and for downloading firmware.
The USB host is responsible for supplying the VUSB_IN line. This line is for voltage detection
only. The USB part (driver and transceiver) is supplied by means of BATT+. This is because
PH8/PH8-P is designed as a self-powered device compliant with the “Universal Serial Bus
Specification Revision 2.0”
1
.
Figure 2: USB circuit
To properly connect the module's USB interface to the host a USB 2.0 compatible connector is
required. Furthermore, the USB modem driver distributed with PH8/PH8-P needs to be in-
stalled.
While the USB connection is active, the module will not change into SLEEP Mode. To enable
switching into SLEEP mode the USB host must bring its USB interface into Suspend state (see
“Universal Serial Bus Specification Revision 2.0“
1
for a description of the Suspend state). On
incoming calls PH8/PH8-P will then generate a remote wake up request to resume the USB
connection (active low). If configured for SDPORT=6, i.e., if using a CDC ACM compatible USB
driver on the host system, a selective suspend on the USB host may not be supported and the
module may therefore not be able to change into SLEEP mode.
As an alternative to the regular USB remote wakeup mechanism it is possible to employ the
RING0 or WAKEUP line to wake up the host application. The benefit is that the RING0 or
WAKEUP lines can wake up the host application in case of incoming calls or other events sig-
nalized by URCs while the USB interface is suspended or shut down.
1.
The specification is ready for download on http://www.usb.org/developers/docs/
VBUS
DP
DN
VREG (3V075)
BATT+
USB_DP
2)
lin. reg.
GND
Module
Detection only
VUSB_IN
USB part
1)
RING0
Host wakeup
1)
All serial and pull-up resistors for data lines are implemented.
USB_DN
2)
2)
If the USB interface is operated in High Speed mode (480MHz), it is recommended to take
special care routing the data lines USB_DP and USB_DN. Application layout should in this
case implement a differential impedance of 90Ohm for proper signal integrity.
WAKEUP
B2B