User Manual

EHS6 Hardware Interface Overview
2 Interface Characteristics
21
EHS6_HIO_v01.441 Page 10 of 38 2013-07-11
Confidential / Preliminary
2 Interface Characteristics
EHS6 is equipped with an SMT application interface that connects to the external application.
The SMT application interface incorporates the various application interfaces as well as the RF
antenna interface.
2.1 Application Interface
2.1.1 USB Interface
EHS6 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
EHS6 is designed as a self-powered device compliant with the “Universal Serial Bus Specifi-
cation 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 EHS6 needs to be installed.
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 (including R
S
) 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.
R
S
R
S
SMT