The CMX865A is a DTMF Codec/FSK Combo multi-standard modem for use in Wireless Local Loop, including Fixed Wireless Terminals and Fixed Wireless Phone installations and Short Message Service telephone systems.
Flexible line driver, hybrid and receiver circuits are integrated on chip, requiring only passive external components to build a 2 or 4-wire line interface.
POTS Signalling
A high-quality DTMF decoder with excellent immunity to falsing-on-voice, and a standard DTMF encoder are included. Alternatively, these blocks can be used to transmit and detect user-specific: programmed single and dual-tone signals, simple melodies, call progress signals or modem calling and answering tones.
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Q. CMX865A: The DTMF de-response is given as 30ms max but I measure more than this on some DTMF digits under certain conditions.
A. The de-response time of the DTMF decoder is correct.
The programmer cannot see the DTMF response/de-response directly. What the programmer sees is b5 which loosely tracks the DTMF decoder response.
When a DTMF digit ends, the DTMF decoder will de-respond and some time later b5 will signal this by going low.
To allow for polling, the minimum time that b5 is high is 14ms. To ensure that short DTMF digits with short gaps between can be detected in the code, b5 will de-respond when energy from the following tone is detected. Under these conditions the maximum high time for b5 is 30ms. This maximum high time is called the DTMF de-response time.
Note that with longer DTMF tones and longer gaps, b5 can be high for more than 30ms.
This downloadable graphic shows the response of b5 in a number of different receive scenarios.
Q. Can you detail the differences of the CMX865A with respect to the CMX865?
A. The listings below should help you:
CMX865A Advantages over CMX865
CMX865A Functional Difference from the CMX865
Development Support
Summary
This application note comprises the Filter Coefficient Generator program as an Excel spreadsheet as well as operational instructions.
This document aims to assist modem product designers using and understanding Short Message Service (SMS) applications. CML Microcircuits' (CML) integrated circuit devices (CMX85x and CMX86x) could be used to realize and achieve a Caller Line Identification (CLI), SMS or Low Rate Messaging Service (LRMS) data transfer within a wireline system.
Caller Line ID (CLI) was originally developed for the US market but has become commonplace throughout the World because of its multitudinous applications. There are a number of CLI protocols to which telephone equipment manufacturers must comply. This document gives an overview of two types; BELL GR-30-CORE/SR-TSV-002476 (or ETSI 300 659-1 section 6.1.1) used in the USA and most of the world and Caller Line Identification Presentation (CLIP) BT SIN 227 (or ETSI ETS 300 659-1 section 6.1.2c) used in the UK.
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.
Security alarm panels are used around the world as a cost-effective means of protecting people and property. The Security Industry Association (SIA)1, a trade organization that represents security market companies, has developed protocols that describe the communications link used by these panels. DTMF tones, pulsed tones, and frequency-shift keying (FSK) are common signaling methods used throughout these SIA protocols. The CMX865A low-power wireline modem can be easily configured to perform these SIA protocols making it attractive for security panel applications. The purpose of this document is to describe how the CMX865A can be made to perform SIA communication protocols.
CMX865A: Motorola MC145443 to CMX865A Migration
CMX865A Employed in Short Local Loops (SLL)
Transmits FSK including a preamble. There is additional code for dialling and call progress. Works with the Rx FSK.pes file.
A script that receives FSK including the preamble detection. There is additional code for the support of call progress. Works with the Tx FSK.pes file.
A simple script to reset the device and put it into operating mode.
A simple script to reset the device and put it into powersave mode.
Sets up the Programmable Tone Generators (PTG) to generate custom tones or simple melodies. A spreadsheet to calculate the required values, can be downloaded from the Knowledge Base Tab.
To Set the CMX865A into DTMF decode mode.
Audacity Project files for Ademco emulation.
To set up the CMX865A Programmable Tone Detectors (PTD) for decoding the Ademco handshake and kissoff tones.
Voice record and playback files using the CMX865A. Please refer to the Applications section of the datasheet.
Uses the ADC in test mode to read the DC voltage across the line (snoop resistors required) to determine: "Line connected"/"not-connected" or "Line-in-use". Also contains a sub to reset the core to allow the method to be used with general modem function.
An Excel spreadsheet that calculates the values required for the Programmable Tone Generators. Single tones and dual-tones are allowed. The spreadsheet predicts the actual frequency and amplitude of each tone.
Guides to operation and interfacing