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Subject: CMX869B DAA Circuit with Line State Detection
The circuitry used to connect a modem to a telephone line, also referred to as a “direct access arrangement” or
DAA, can represent a significant hurdle for some customers.
To assist these customers, this application note describes one method of connecting the CMX869B
to the
telephone network using low-cost components.
In addition to the basic DAA function, other circuitry is provided for the CID and 911 detection functions.
[application program link].
Subject: Recommendations for V.23 1200/75 b/s duplex call set-up
V.23 recommendations do not describe how a connection is established; a procedure is described below and
illustrated in Figure 1; however you should not rely on other modems following this particular flow.
Note also that 1200/1200 bps half-duplex connections are not covered by this application note.
[application note link].
Subject: CMX868, CMX869 and CMX869A Modems with CLARE Litelink DAA
This application note describes how the Clare CPC5621 optical DAA can be used to interface the CMX868 V.22bis and
CMX869 V.32bis modem chips to the telephone line.
The primary benefit of the Clare LightLink DAA is that it requires very little board area and has a very low
profile. This can be important in applications where there are tight space constraints.
[application note link].
Subject: Silver Telecom Application Notes
Silver Telecoms specialises in wireline telecoms line-interface modules, some of which employ CML IC products.
A visit to this website will provide further support to designers of such interfaces.
[application program link].
Subject: CMX86x and CMX850 Filter Coefficient Generator Program
This application comprises the Filter Coefficient Generator program as an Excel spreadsheet.
[application program link].
CMX868 Programmer's Quick Reference
With modern fabrication techniques it is becoming increasing common to see more peripheral circuits added to the
basic functionality of integrated circuits.
This trend toward increasingly complex devices is good for the user in that it simplifies the overall design,
reduces external hardware and lowers cost whilst giving increased flexibility.
The trade-off is that the device becomes more difficult to understand and manage as previously separate functions
become interrelated and inter-dependent.
[application note link].
The CMX869x Modem Series Upgrade Path
The CMX869x modem series provides the functions necessary to implement a V.32 bis automode modem and includes
all of the signaling likely to be required within the General Switched Telephone Network, GSTN or PSTN.
Some applications normally use a low data rate for regular traffic but require a much higher data rate for
occasional traffic.
To support such applications the original CMX869 specification has been extended through the CMX869A and CMX869B.
There are no pin-out or signal differences between the CMX869x devices so they may be used interchangeably in the
same hardware.
However, extending the function set required minor register bit re-assignments that affect firmware portability.
The aim of this document is to illustrate these changes and to detail the migration of code between devices in
the series.
[application note link].
Bell 212A Implementation with the CMX869A
The CMX869A V.32bis modem IC from CML Microcircuits offers multiple modem protocol support in
both automodem and manual modes, a rich telephony feature set, and low power consumption.
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The purpose of this document is to describe how Bell 212A can be supported using the V.22 mode of the CMX869A modem IC.
[application note link].
Subject: Auto-modem - Incorrect Bit-Rate Determination
During the start-up and retrain procedures, the CMX869A determines a likely bitrate at which satisfactory
performance can be attained with the particular GSTN connection.
Under exceptional conditions, it is possible that the CMX869A will determine an incorrect bitrate resulting in
reduced BER performance.
This Application Note describes a method to both detect and work-around this anomaly.
[application program link].
Subject: Caller Line ID with the CMX869A
CLI operates in two distinctly different modes, on-hook and off-hook, which are often referred to as type 1 and
type 2 respectively.
The on-hook mode is the most widely used because the CLI is delivered before the call is accepted.
Here the calling parties identity may be used within the system in a decision making process.
For example, a simple call filter that rejects calls from callers who withhold their own number.
Off-hook systems find more limited use because the target function is to let the called party know the identity
of a missed caller.
This document covers only on-Hook or type 1 CLI although the principles may be extended for some type 2 services.
[application program link].
Subject: V.22bis Full-Duplex Call Set-up on the CMX869A
This document provides details on the V.22bis wire-line communications protocol and pointers on how the handshaking
sequence can be achieved with the CMX869A modem IC using the manual modem mode.
Also included is additional information on the V.14 and V.25 protocols.
[application program link].