Table of Contents
Advertisement
AC75 Hardware Interface Description
Strictly confidential / Preliminary
3.10
Serial Interface ASC0
AC75 offers an 8-wire unbalanced, asynchronous modem interface ASC0 conforming 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 2.9V (for high data bit or
inactive state). For electrical characteristics please refer to Table 26.
AC75 is designed for use as a DCE. Based on the conventions for DCE-DTE connections 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
GSM Module (DCE)
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 primarily designed for controlling voice calls, transferring CSD, fax and GPRS
data and for controlling the GSM engine with AT commands.
•
Full Multiplex capability allows the interface to be partitioned into three virtual channels,
yet with CSD and fax services only available on the first logical channel. Please note that
when the ASC0 interface runs in Multiplex mode, ASC1 cannot be used. For more details
on Multiplex mode see [5].
•
The DTR0 signal will only be polled once per second from the internal firmware of AC75.
•
The RING0 signal serves to indicate incoming calls and other types of URCs (Unsolicited
Result Code). It can also be used to send pulses to the host application, for example to
wake up the application from power saving state. See [1] for details on how to configure
the RING0 line by AT^SCFG.
•
By default, configured for 8 data bits, no parity and 1 stop bit. The setting can be
changed using the AT command AT+ICF and, if required, AT^STPB. For details see [1].
•
ASC0 can be operated at fixed bit rates from 300 bps to 460,800 bps.
•
Autobauding supports bit rates from 1,200 to 460,800 bps.
•
Autobauding is not compatible with multiplex mode.
•
Supports RTS0/CTS0 hardware flow control and XON/XOFF software flow control.
AC75_HD_V00.202
TXD0
RXD0
RTS0
CTS0
DTR0
DSR0
DCD0
RING0
Figure 16: Serial interface ASC0
Page 53 of 120
s
Application (DTE)
TXD
RXD
RTS
CTS
DTR
DSR
DCD
RING
27.04.2006
Advertisement
Table of Contents
