Feature Phones with Data Interfaces
Pay-Phones
PABX Telephones + Data
Data Terminal Adapters
EPOS Terminals
Remote Metering and Alarm Systems
H.320 Video Phones
Reference Designs Available
DTMF Rx
CLI
A
S
L
POTS 1
I
C
B
•
Supports ITU Specifications
•
Supports Incoming and Outgoing Calls
•
Auto-bauding and Auto-parity
•
Hayes Compatible 'AT' Command Set
•
V.120 Rate Adaption
•
PPP Async to Sync Conversion
•
Supports CTR3 Approval
•
Voice and User Data via B Channels
Full API Available
•
RS232
Interface
Driver
RS232
The CMX218 is an ISDN data and telephony protocol engine which implements the lower level ISDN interface
and communicates with the CMX605 and other standard devices to form a fully integrated ISDN chipset for
both voice and data communications. The CMX218 puts all the main data processing elements in a single
device. No ISDN software has to be written and simple ‘Plug and Play’ design results. This reduces
development time and provides a highly cost-effective hardware solution. By using proven circuit designs, the
designer can move quickly from initial concept through design in to manufacture.
The CMX218 supports one voice port over the ISDN Line, which can be used to provide ISDN telephony
services or a POTS line interface, and a single data channel, capable of operation at 115,200 bps. The
CMX218 features a full set of ‘Hayes’ compatible AT command codes on its asynchronous data interface, in
addition to providing keypad-configurable voice telephony services. The CMX218’s feature set and
architecture allow most analog systems to be converted to an ISDN equivalent with enhanced features.
The CMX218 is designed to work with the AMD 79C30 S/T bus interface, the Siemens PSB-21525 HDLC
formatter and the MX-COM CMX605 POTS interface circuit, and also comes complete with embedded
applications software. To support the CMX218, MX-COM can also provide licensed reference designs on
user request. A flexible Applications Program Interface (API) allows users to customize the features and
operation of their own design. The CMX218 is available in an 80-pin QFP (CMX218S1) package.
1
The CMX218 is a data processor integrated circuit that supports the protocol layers 1, 2 and 3 of the ISDN protocol stack in accordance
with the specifications of CCITT (now ITU). These specifications, which are widely used around the world, might not be supported within
the U.S.
24 A19 output Memory and Peripheral Address Bus
25 A18 output Memory and Peripheral Address Bus
26 A17 output Memory and Peripheral Address Bus
27 A16 output Memory and Peripheral Address Bus
28 A15 output Memory and Peripheral Address Bus
29 A14 output Memory and Peripheral Address Bus
30 A13 output Memory and Peripheral Address Bus
31 A12 output Memory and Peripheral Address Bus
32 A11 output Memory and Peripheral Address Bus
33 A10 output Memory and Peripheral Address Bus
34 A9 output Memory and Peripheral Address Bus
35 A8 output Memory and Peripheral Address Bus
36 A/D7 bi-directional Memory and Peripheral Address and Data Bus
37 A/D6 bi-directional Memory and Peripheral Address and Data Bus
38 A/D5 bi-directional Memory and Peripheral Address and Data Bus
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ISDN Data and Telephony Protocol Engine (no X.25) 6 CMX218 Advance Information
S1 Package Signal
Description
Pin No. Name Type
39 A/D4 bi-directional Memory and Peripheral Address and Data Bus
40 A/D3 bi-directional Memory and Peripheral Address and Data Bus
41 A/D2 bi-directional Memory and Peripheral Address and Data Bus
42 A/D1 bi-directional Memory and Peripheral Address and Data Bus
43 A/D0 bi-directional Memory and Peripheral Address and Data Bus
44 ASTB output Address/Data Bus Strobe (data bus selected if low)
DV
45
46 ~ input
SS0
power The digital negative supply rail (ground)
For manufacturer's use only. Connect to DV
directly
SS
47 PSBRES output HDLC Chip Reset
48 N/C output Do not make any connection to this pin
49 N/C output Do not make any connection to this pin
50 API-RXD input API/RS232 Port 2 Rx Data (inactive = high)
51 API-TXD output API/RS232 Port 2 Tx Data (high when inactive)
52 N/C output Do not make any connection to this pin
53 N/C output Do not make any connection to this pin
54 ILFI output ISDN Line Failure Indicator
55
DV
DD0
power
The digital positive supply rail. Levels and voltages are
dependent upon this supply. This pin should be decoupled
to DV
by a capacitor
SS
56 RING1 output POTS Port Ringing Generator (low when not ringing)
57
1RING
58 CLIP1 output
output POTS Port Ringing Generator (high when not ringing)
POTS Port Line Voltage Adjustment (low when sending FSK
to a Caller Display unit. If low, it makes the SLIC present a
high impedance to the POTS line)
59 ILINE1 input
POTS Port Hook Switch Status Detector
(on-hook = low)
60
∼
input
For manufacturers’ use only. Connect to DV
SS
directly
61 REPLY input CMX605 C-BUS Interface - Reply Data
62 CMD-DATA output CMX605 C-BUS Interface - Command Data
63 SER-CLK output CMX605 C-BUS Interface - Serial Clock
64
65
66
67
AV
AV
AV
DD
REF1
SS
1CS
power
The positive analog supply rail. Levels and voltages are
dependent upon this supply. This pin should be decoupled
power
to AV
A/D Reference Voltage. Connect to AVDD directly
by a capacitor
SS
power The negative analog supply rail (ground)
output CMX605 C-BUS Interface (chip select for POTS Port)
68 N/C output Do not make any connection to this pin
69
70
AV
AV
REF2
REF3
power
power
71 NMI input
D/A Reference Voltage. Connect to AVDD directly
D/A Reference Voltage. Connect to AVSS directly
For manufacturer's use only. Connect to DV
directly
SS
72 API-INT input API Interrupt (inactive = high)
73
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ISDN Data and Telephony Protocol Engine (no X.25) 7 CMX218 Advance Information
S1 Package Signal
Description
Pin No. Name Type
74 PSBINT input HDLC Chip Interrupt
75 RXD1 input RS232 Port 1 Received Data - used for autobauding
76 RTS1 input RS232 Port 1 Ready To Send (inactive = high)
77 ISDNINT input ISDN S-interface Chip Interrupt
78 DTR1 input RS232 Port 1 Data Terminal Ready (inactive = high)
79 RXD1 input RS232 Port 1 Received Data (inactive = high)
80 TXD1 output RS232 Port 1 Transmitted Data (high when inactive)
3. External Components
V
DD
SCL
SDA
ISDNRST
RI1
DCD1
CTS1
RST
DV
DD1
XTAL
XTAL
DV
SS1
LED1
LED2
LED3
LED4
LED5
LED6
LED7
LED8
N/C
CS1
V
DD
SS
REF1
DD
AV
AV
AV
REPLY
SER-CLK
CMD-DATA
(V )
SS
ILINE1
CLIP1
RING1
RING1
DV
ILFI
N/C
N/C
API-TXD
API-RXD
N/C
N/C
PSBRES
(V )
DV
ASTB
A/D0
A/D1
A/D2
SS
DD0
SS0
V
DD
V
DD
RXD1
REF2
REF3
AV
TXD1
RXD1
DTR1
RTS1
ISDNINT
RXD1
PSBINT
IRQ
API-INT
NMI
AV
CMX218S1
ST
LED9
WR
RD
A19
A18
A17
A16
A15
A14
A13
A12
A11
A10
A9
A/D7
A/D6
A/D5
A/D4
A/D3
V
SS
A8
Figure 2: CMX218 Pin Out
This product is to be used as part of a chip-set. Please refer to the Applications Section
Note:
(See Section 5) for details of the recommended chip-set.
All trademarks and service marks are held by their respective companies
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 preprogrammed 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
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.
All trademarks and service marks are held by their respective companies
ISDN Data and Telephony Protocol Engine (no X.25) 9 CMX218 Advance Information
4.1 Glossary
ACCM
API
CIDCW
CLI
CRC
CTS
DCD
DDI
DTE
DTMF
DTR
HDLC
IA5
IE
ILFI
ISDN
LAPB
LAPD
LCGN
LED
LLI
MFO
MSN
NUA
NUI
PAD
PC
PCM
POTS
PPP
PVC
RI
RNR
RR
RTS
SABM
SABME
SLIC
SPM
SVC
TEI
Asynchronous Control Character Map
Application Programmer’s Interface
Caller Identification During Call Waiting
Calling Line Identification
Cyclic Redundancy Check
Clear to Send
Data Carrier Detect
Direct Dialing Inwards
Data Terminal Equipment
Dual Tone Multiple Frequency
Data Terminal Ready
High Level Data Link Control
International Alphabet No 5
Information Element
ISDN Line Failure Indicator
Integrated Services Digital Network
Link Access Procedure - Balanced
Link Access Procedure on the D-Channel
Logical Channel Group Number
Light Emitting Diode
Logical Link Identifier
Multiple Frame Operation
Multiple Subscriber Numbering
Network User Address
Network User Identification
Packet Assembler/Disassembler
Personal Computer
Pulse Code Modulation
Plain Old (Analog) Telephone Service
Point to Point Protocol
Permanent Virtual Circuit
Ring Indication
Receiver Not Ready
Receiver Ready
Ready to Send
Set Asynchronous Balanced Mode
Set Asynchronous Balanced Mode Extended
Subscriber Line Interface Circuit
Subscriber Pulse Metering
Switched Virtual Circuit
Terminal Endpoint Identifier