CMX218S1 データシートの表示（PDF） - MX-COM Inc

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CMX218S1

ISDN Data and Telephony Protocol Engine

MX-COM Inc  

ISDN Data and Telephony Protocol Engine (no X.25)

8

CMX218 Advance Information

4. General Description

The CMX218 is a single-chip data processor that has been mask programmed with firmware to implement an

ISDN protocol stack. This enables the CMX218 to interface an analog (POTS) port and a digital (RS232) port

to an ISDN S-bus network connection. Key variables are stored in an external EEPROM and the user can

provide additional features by adding external ROM and RAM. Access to the firmware Application

Programmer's Interface (API) facilitates the seamless integration of the user's additional features with the pre-

programmed ISDN to POTS and RS232 interfaces.

The CMX218 is intended for use as part of an ISDN chipset and all descriptions in this data sheet refer to this

implementation, which is shown diagrammatically in Figure 3. The use of alternative chipsets is not

supported.

The firmware supports connection to an ISDN S-bus network interface via the Siemens PSB21525 HDLC

controller and the AMD AM79C30 ST controller with integral PCM codec for a single POTS port.

The CMX218 interfaces with a CMX605 Tone Generator and DTMF Receiver chip, which decodes incoming

DTMF tones and generates certain call progress signals (e.g. busy tone) normally originating from an analog

telephone exchange. The firmware translates the CMX605 data into ISDN D-channel commands and vice

versa to support both incoming and outgoing calls. For the ISDN interface, D-channel commands sufficient

for standard telephony applications are implemented. With the aid of a small amount of discrete circuitry,

exchange battery voltage, ringing current, line reversal and off-hook detection are also supported, to complete

the POTS interface.

The CMX218 also provides a data port that can drive a standard RS232 interface with the aid of a Maxim

MAX238, or similar, level converter. The firmware provides support for incoming and outgoing data calls,

RS232 auto-bauding from 9600bps to 115200bps, auto parity detection, RTS/CTS flow control, call clearing

on loss of DTR, V.120 rate adaption, PPP async to sync conversion and a comprehensive set of Hayes

commands (which facilitate the use of normal PC-based modem software). The CMX218 has dedicated

outputs for visible indicators (LEDs) that can be used to provide information on the call status. Support for

Multiple Subscriber Numbering is also included in the firmware.

The CMX218 can be configured either by means of keypad (DTMF) programming via the POTS port or by

means of an extended Hayes command set via the RS232 port. Configuration parameters allow the user to

change (for example) the format and cadence of the ringing signal, so as to facilitate use of the CMX218 in

different countries. Each POTS and RS232 interface is able to configure the variables relevant to its own use.

An Application Programmer's Interface (API) is available and is described separately in Section 4.8. Further

details are available on completion of a Non-Disclosure Agreement. Please contact MX-COM directly for

further details.

The firmware and finite state machine embedded in the CMX218 have been used in products that have

gained ETSI CTR3 approval.

MX-COM, Inc

4800 Bethania Station Road, Winston-Salem, NC, 27105-1201, USA

www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054

All trademarks and service marks are held by their respective companies

2000 MX-COM, Inc.

Doc. # 20480215.001

2000 Chiron Technology Limited

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