User's Manual

EHS5-E/EHS5-US Hardware Interface Overview
2.1 Application Interface
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EHS5_HIO_v01.000 Page 11 of 35 2012-11-14
Confidential / Preliminary
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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. Al-
so, VUSB_IN should always be kept enabled for this functionality. See “Universal Serial Bus
Specification Revision 2.0“
1
for a description of the Suspend state. On incoming calls EHS5-E/
EHS5-US will then generate a remote wake up request to resume the USB connection (active
low).
As an alternative to the regular USB remote wakeup mechanism it is possible to employ the
RING0 line to wake up the host application. The benefit is that the RING0 line can wake up the
host application in case of incoming calls or other events signalized by URCs while the USB
interface is suspended or shut down.
2.1.2 Serial Interface ASC0
EHS5-E/EHS5-US offers an 8-wire unbalanced, asynchronous modem interface ASC0 con-
forming to ITU-T V.24 protocol DCE signalling. The electrical characteristics do not comply with
ITU-T V.28. The significant levels are 0V (for low data bit or active state) and 1.8V (for high data
bit or inactive state).
EHS5-E/EHS5-US is designed for use as a DCE. Based on the conventions for DCE-DTE con-
nections it communicates with the customer application (DTE) using the following signals:
• Port TXD @ application sends data to the module’s TXD0 signal line
• Port RXD @ application receives data from the module’s RXD0 signal line
Figure 3: Serial interface ASC0
Features:
• Includes the data lines TXD0 and RXD0, the status lines RTS0 and CTS0 and, in addition,
the modem control lines DTR0, DSR0, DCD0 and RING0.
• ASC0 is designed for controlling GSM/UMTS voice calls, transferring data and for control-
ling the module with AT commands.
• Full multiplexing capability allows the interface to be partitioned into virtual channels.