CMX228
ISDN Protocol Engine
with D - channel Data
D/228/1 October 1999
Advance Information
Features
Applications
•
Full ISDN Voice and Data Services
•
Feature Phones with Data Interfaces
•
V.120 / PPP Operation
•
Pay-Phones and H.320 Video Phones
•
Hayes Compatible 'AT' Command Set
•
EPOS Terminals
•
Supports CTR3 Approval
•
Remote Metering and Alarm Systems
•
User Data and X.25 via B and Dchannels
•
Data Terminal Adapters
•
Full API Available
•
Reference Designs Available
1.1
Brief Description
The CMX228 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. It puts all the main data processing elements in one device, no ISDN
software has to be written and simple ‘Plug and Play’ design results. The CMX228 supports one voice port,
which can be used to provide ISDN telephony services or a POTS line interface, and one data channel,
capable of operation at 115,200 b/s. It also has a full set of ‘Hayes’ compatible AT command codes on its
asynchronous data interface and keypad-configurable voice telephony services.
The CMX228 is designed to work with the AMD 79C30 S/T bus interface, the Siemens PSB-21525 HDLC
formatter and the CML CMX605 POTS interface circuit, and also comes complete with embedded applications
software. In addition, the CMX228 offers data transfer (up to 16kb/s) over the D-channel by using the X.25
protocol. To support the CMX228, CML can also provide licensed reference designs on user request. A
flexible Applications Program Interface (API) allows users to customise the features and operation of their own
design. The CMX228 comes in a compact 80-pin surface mount package.
1999 Consumer Microcircuits Limited
1999 Chiron Technology Limited
ISDN Data and Telephony Protocol Engine (inc. X.25)
CMX228
CONTENTS
Section
Page
1.0 Features and Applications .........................................................................1
1.1 Brief Description.........................................................................................1
1.2 Block Diagram ............................................................................................4
1.3 Signal List ...................................................................................................5
1.4 External Components.................................................................................8
1.5 General Description....................................................................................9
1.5.1 Glossary ....................................................................................10
1.5.2 Initialisation...............................................................................11
1.5.3 ISDN Interface............................................................................11
1.5.3.1 Activation.....................................................................11
1.5.3.2 De-activation or Line Disconnection .............................11
1.5.3.3 Line Failure Detection ..................................................11
1.5.3.4 Incoming Calls .............................................................12
1.5.3.5 Multiple Subscriber Numbering.....................................12
1.5.3.6 Channel Mapping.........................................................12
1.5.4 POTS Configuration..................................................................13
1.5.4.1 Configuration and Control via DTMF Keypad................13
1.5.5 POTS Operation ........................................................................15
1.5.5.1 Keypad Operation ........................................................15
1.5.5.2 Incoming POTS Calls...................................................15
1.5.5.3 Outgoing POTS Calls...................................................15
1.5.5.4 Connected Calls...........................................................16
1.5.5.5 Call Clearing ................................................................16
1.5.6 Data Configuration....................................................................17
1.5.6.1 Hayes Command Set...................................................17
1.5.6.2 Hayes Register Set ......................................................22
1.5.6.2.1 X.25 Virtual Circuit Parameters .................................23
1.5.6.2.2 X.25 Parameters.......................................................24
1.5.6.2.3 V.120 Parameters .....................................................25
1.5.6.2.4 X.25 PAD Parameters...............................................25
1.5.6.2.5 B Channel LAPB Parameters ....................................26
1.5.6.2.6 Basic Configuration Parameters ................................26
1.5.7 Data Operation ..........................................................................28
1.5.7.1 Incoming B-Channel Data Calls....................................28
1.5.7.2 Outgoing B-Channel Data Calls....................................28
1.5.7.3 X.25 Data Calls on the D-Channel................................28
1.5.7.4 Connected Calls...........................................................28
1.5.7.5 Call Clearing ................................................................28
1.5.8 Application Programmer's Interface ........................................29
1.5.9 Hardware Description ...............................................................30
1.5.9.1 LED Status Indicators (LED1 to LED9, and ILFI)..........30
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CMX228
1.6 Application Notes .....................................................................................31
1.6.1 General ......................................................................................31
1.6.2 Approvals ..................................................................................31
1.7 Performance Specification.......................................................................32
1.7.1 Electrical Performance..............................................................32
1.7.1.1 Absolute Maximum Ratings..........................................32
1.7.1.2 Operating Limits...........................................................32
1.7.1.3 Operating Characteristics.............................................33
1.7.2 Packaging..................................................................................38
Note: This product is in development: Changes and additions will be made to this
specification. Items marked TBD or left blank will be included in later issues.
Information in this data sheet should not be relied upon for final product design.
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ISDN Data and Telephony Protocol Engine (inc. X.25)
1.2
CMX228
Block Diagram
Figure 1 Block Diagram
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ISDN Data and Telephony Protocol Engine (inc. X.25)
1.3
CMX228
Signal List
S1 Package
80QFP
Signal
Description
Pin No.
Name
Type
1
SCL
O/P
EEPROM - Serial Clock
2
SDA
BI
EEPROM - Serial Data
3
ISDNRST
O/P
ISDN S-interface Chip Reset
4
RI1
O/P
RS232 Port1 Ring Indicator (high when inactive)
5
DCD1
O/P
RS232 Port1 Data Carrier Detect (high when inactive)
6
CTS1
O/P
RS232 Port1 Clear To Send (high when inactive)
7
RSTN
I/P
CMX228 Chip Reset (active low)
8
DVDD1
Power
9
XTALN
O/P
The output of the on-chip Xtal oscillator inverter
10
XTAL
I/P
The input to the oscillator inverter from the Xtal circuit
11
DVSS1
Power
12
LED1
O/P
POTS Port Off-Hook Indicator (HK1)
13
LED2
O/P
RS232 Port 1 Auto-Answer Indicator (AA)
14
LED3
O/P
RS232 Port 1 Data Carrier Detect Indicator (DCD)
15
LED4
O/P
RS232 Port 1 Ready To Send Indicator (RTS)
16
LED5
O/P
RS232 Port 1 Receive Data Indicator (RXD)
17
LED6
O/P
RS232 Port 1 Transmit Data Indicator (TXD)
18
LED7
O/P
RS232 Port 1 Data Terminal Ready Indicator (DTR)
19
LED8
O/P
ISDN Line Activated Indicator (AR)
20
STN
O/P
Watchdog Timer Stimulus
21
LED9
O/P
POTS Port Call Connected Indicator (CN1)
22
WRN
O/P
Memory Write Access Strobe
23
RDN
O/P
Memory Read Access Strobe
24
A19
O/P
Memory and Peripheral Address Bus
25
A18
O/P
Memory and Peripheral Address Bus
26
A17
O/P
Memory and Peripheral Address Bus
27
A16
O/P
Memory and Peripheral Address Bus
28
A15
O/P
Memory and Peripheral Address Bus
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The digital positive supply rail. Levels and voltages are
dependent upon this supply. This pin should be
decoupled to DVSS by a capacitor
The digital negative supply rail (ground)
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ISDN Data and Telephony Protocol Engine (inc. X.25)
S1 Package
80QFP
CMX228
Signal
Description
Pin No.
Name
Type
29
A14
O/P
Memory and Peripheral Address Bus
30
A13
O/P
Memory and Peripheral Address Bus
31
A12
O/P
Memory and Peripheral Address Bus
32
A11
O/P
Memory and Peripheral Address Bus
33
A10
O/P
Memory and Peripheral Address Bus
34
A9
O/P
Memory and Peripheral Address Bus
35
A8
O/P
Memory and Peripheral Address Bus
36
A/D7
BI
Memory and Peripheral Address and Data Bus
37
A/D6
BI
Memory and Peripheral Address and Data Bus
38
A/D5
BI
Memory and Peripheral Address and Data Bus
39
A/D4
BI
Memory and Peripheral Address and Data Bus
40
A/D3
BI
Memory and Peripheral Address and Data Bus
41
A/D2
BI
Memory and Peripheral Address and Data Bus
42
A/D1
BI
Memory and Peripheral Address and Data Bus
43
A/D0
BI
Memory and Peripheral Address and Data Bus
44
ASTB
O/P
45
DVSS0
Power
46
~
I/P
For manufacturer's use only. Connect to DVSS directly
47
PSBRES
O/P
HDLC Chip Reset
48
N/C
O/P
Do not make any connection to this pin
49
N/C
O/P
Do not make any connection to this pin
50
API-RXD
I/P
API/RS232 Port 2 Rx Data (inactive = high)
51
API-TXD
O/P
API/RS232 Port 2 Tx Data (high when inactive)
52
N/C
O/P
Do not make any connection to this pin
53
NC
O/P
Do not make any connection to this pin
54
ILFI
O/P
ISDN Line Failure Indicator
55
DVDD0
Power
56
RINGP1
O/P
POTS Port Ringing Generator (low when not ringing)
57
RINGN1
O/P
POTS Port Ringing Generator (high when not ringing)
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Address/Data Bus Strobe (data bus selected if low)
The digital negative supply rail (ground)
The digital positive supply rail. Levels and voltages are
dependent upon this supply. This pin should be
decoupled to DVSS by a capacitor
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D/228/1
ISDN Data and Telephony Protocol Engine (inc. X.25)
S1 Package
80QFP
CMX228
Signal
Description
Pin No.
Name
Type
58
CLIP1
O/P
POTS Port Line Voltage Adjustment (low if sending
FSK to a Caller Display unit, as it is intended to make
the SLIC present a high impedance to the POTS line)
59
ILINE1
I/P
POTS Port Hook Switch Status Detector
(on-hook = low)
60
∼
I/P
For manufacturer’s use only. Connect to DVSS directly
61
REPLY
I/P
CMX605 C-BUS Interface - Reply Data
62
CMDDATA
O/P
CMX605 C-BUS Interface - Command Data
63
SER-CLK
O/P
CMX605 C-BUS Interface - Serial Clock
64
AVDD
Power
The positive analogue supply rail. Levels and voltages
are dependent upon this supply. This pin should be
decoupled to AVSS by a capacitor
65
AVREF1
Power
A/D Reference Voltage. Connect to AVDD directly
66
AVSS
Power
The negative analogue supply rail (ground)
67
CSN1
O/P
CMX605 C-BUS Interface (chip select for POTS Port)
68
N/C
O/P
Do not make any connection to this pin
69
AVREF2
Power
D/A Reference Voltage. Connect to AVDD directly
70
AVREF3
Power
D/A Reference Voltage. Connect to AVSS directly
71
NMI
I/P
For manufacturer's use only. Connect to DVSS directly
72
API-INT
I/P
API Interrupt (inactive = high)
73
IRQN
I/P
CMX605 C-BUS Interface - Interrupt (inactive = high)
74
PSBINT
I/P
HDLC Chip Interrupt
75
RXD1
I/P
RS232 Port 1 Received Data - used for autobauding
76
RTS1
I/P
RS232 Port 1 Ready To Send (inactive = high)
77
ISDNINT
I/P
ISDN S-interface Chip Interrupt
78
DTR1
I/P
RS232 Port 1 Data Terminal Ready (inactive = high)
79
RXD1
I/P
RS232 Port 1 Received Data (inactive = high)
80
TXD1
O/P
RS232 Port 1 Transmitted Data (high when inactive)
Notes: I/P =
O/P =
BI
=
Input
Output
Bidirectional
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ISDN Data and Telephony Protocol Engine (inc. X.25)
1.4
CMX228
External Components
Note: This product is to be used as part of a chip-set. Please refer to the Applications Section
(section 1.6) for details of the recommended chip-set.
Figure 2 CMX228 Pinout
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ISDN Data and Telephony Protocol Engine (inc. X.25)
1.5
CMX228
General Description
The CMX228 is a single-chip data processor which has been mask programmed with firmware to
implement an ISDN protocol stack. This enables the CMX228 to provide an analogue (POTS) port
and a digital (RS232) port with 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 CMX228 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 CMX228 interfaces with a CMX605 Tone Generator and DTMF Receiver chip, which decodes
incoming DTMF tones and generates call progress signals (eg busy tone) normally originating from an
analogue 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, Dchannel 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 CMX228 also provides a data port which 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, X.25
protocol on both B and D-channels, packet assembly and disassembly for X.25, and a comprehensive
set of Hayes commands (which facilitate the use of normal PC-based modem software). The
CMX228 has dedicated outputs for visible indicators (LEDs) which can be used to provide information
on the call status. Support for Multiple Subscriber Numbering is also included in the firmware.
The CMX228 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 CMX228 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 1.5.8.
Further details are available on completion of a Non-Disclosure Agreement. Please contact CML
Sales directly for further details.
The firmware and finite state machine embedded in the CMX228 have been used in products which
have gained ETSI CTR3 approval.
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1.5.1
CMX228
Glossary
ACCM
API
CIDCW
CLI
CRC
CTS
DCD
DDI
DTE
DTMF
DTR
HDLC
IA5
IE
ILFI
ISDN
LAPB
LAPD
LCGN
LED
LLI
MFO
MSN
NU
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 Dialling 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
Number Unobtainable
Network User Address
Network User Identification
Packet Assembler/Disassembler
Personal Computer
Pulse Code Modulation
Plain Old (Analogue) 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
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ISDN Data and Telephony Protocol Engine (inc. X.25)
1.5.2
CMX228
Initialisation
On power-up, the CMX228 assumes its default values, which are factory programmed into the
firmware. It then performs a self-test, during which all of the LED pins and the ILFI pin are held high
for 3s. If the test is unsuccessful, the CMX228 remains in this condition.
If the test is successful, the CMX228 reads its preset values from the attached EEPROM and
examines the state of the ISDN link (ie Layer 1) before commencing normal operation. On power-up,
the ISDN link is de-activated, the POTS port is assumed to be on-hook, ringing is disabled and the
RS232 port is in the Hayes command state.
1.5.3
ISDN Interface
Simultaneous voice and data calls are possible but only one of each type. If a call is active (eg
ringing, connected or clearing down) and an incoming call of the same type (data or voice) is received,
that call will be rejected with user busy as the cause. Incoming calls are firstly checked for other calls
present, then the MSN is checked for validity, then the channel mapping, so that responses will be
handled accordingly.
When channel mapping is enabled, outgoing calls will request the channel enabled. When not
enabled, a request for any channel is made. If no free channels are available for outgoing calls, a
locally generated busy tone is returned to the analogue port or the appropriate Data Call Result Code
is returned to the digital port.
1.5.3.1 Activation
Activation occurs in the following circumstances:
•
•
•
The ISDN network activates.
The device connected to the analogue port goes off hook.
The device connected to the data port sends a Hayes dial command.
The Terminal Endpoint Identifier (TEI) is either negotiated (Hayes register !C7 = 64) or fixed (Hayes
register !C7 = 0 to 63). Line powering of the CMX228 is not supported.
The 'AR' indicator (LED8) toggles between high and low states when the CMX228 is powered up, and
remains constantly low once the CMX228 identifies an activated ISDN line.
ISDN line power detection is not implemented and the CMX228 will negotiate a new TEI on any new
network activation.
1.5.3.2 De-activation or Line Disconnection
De-activation or line disconnection causes the TEI to be removed. Upon re-connection the CMX228
will only be re-activated and request a new TEI when one of the conditions in the above section is met.
1.5.3.3 Line Failure Detection
If the line failure detection parameter is enabled (either via the POTS port or via the RS232 interface)
the CMX228 will check that Layer 2 communications are active every sample period of 30 seconds. If
Layer 2 communications are not active, the CMX228 will attempt to activate them. If they remain
inactive for 2 sample periods, the line is deemed to have failed, so then the ILFI pin is set high. The
CMX228 continues to attempt to activate the line and if it becomes active and stays active for 2
sample periods, then the ILFI pin is set low.
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CMX228
1.5.3.4 Incoming Calls
Incoming voice calls and calls from analogue lines are directed to the analogue port and all other
incoming calls are directed to the RS232 port.
1.5.3.5 Multiple Subscriber Numbering
Multiple Subscriber Numbering (MSN) enables each POTS or RS232 port of the CMX228 to have its
own telephone number. Up to 23 digits can be saved as the MSN for each port.
All incoming SETUP messages will be checked for the presence of a Called Party Number Information
Element (IE). If one is present it is compared with the saved MSN number (if present), starting with
the last digit of both numbers. Comparison continues until there are no more numbers in the MSN
saved number or the incoming Called Party Number or there is a difference between the numbers.
The MSN is said to match if the saved MSN and the incoming calls’ Called Party Number are the
same for the duration of the shorter number (ie if the digit ‘1’ is saved and the received Called Party
Number is 654321, then the MSN matches). If there is no saved MSN, the Called Party Number is
ignored and call processing continues.
When there is a saved MSN and the Calling Party Number transmit is enabled, all outgoing call
SETUP messages will contain a Calling Party Number Information Element.
Note 1: When a CMX228 with MSN saved and Calling Party Number transmit enabled is
connected to some exchanges, no dial tone is heard when going off-hook.
Note 2: Disabling the Calling Party Number transmit will mean that the called party may not
receive the Calling Line Identification (CLI), or if they do receive a CLI it will probably be
the base number and not the number specific to the calling telephone.
1.5.3.6 Channel Mapping
It is possible to configure the CMX228 so that analogue and/or digital ports will only originate calls to
and respond to calls from a specific ISDN B-channel. This is a useful feature if, for example, you wish
to have a hunt group on your ISDN line (ie to select the next available channel) and only want one
voice port to ring on an incoming call.
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1.5.4
CMX228
POTS Configuration
1.5.4.1 Configuration and Control via DTMF Keypad
Configuration can be carried out at any time by causing the POTS port to go off-hook and then
immediately entering a configuration sequence of DTMF tones. The sequence signalled to the
CMX228 will determine the configuration to be performed, as shown in the following table.
Configuration
Sequence
S02S#
S81S#
S81S1n#
Name
Test watchdog
Disable CLI delivery on
port
Use V23 FSK for CLI
delivery
Description
Puts the CMX228 into a permanent
loop, not updating the external
watchdog counter, so after 2s it should
reset.
Inhibits CLI delivery on the analogue
POTS port
Configures modem standard to be used
for CLI delivery.
Default
n/a
n/a
n = alert mode
0 = FSK follows ring burst as per
ETS 300 659-1 para. 6.1.1
1 = FSK follows dual tone alert as per
ETS300 659-1 para. 6.1.2.a
Disabled
2 = FSK follows ringing pulse alert as
per ETSI 300 659-1 para. 6.1.2.b
S81S2#
S90S#
S90Sn#
S93S#
S93Sn#
S94S#
S94Sn#
Use Bell 202 FSK for
CLI delivery
Clear MSN
Save Multiple Subscriber
Number (MSN)
Clear country code
Change country code
Clear channel mapping
Enable channel mapping
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3 = FSK follows line reversal and tone
alert as per ETSI 300 659-1
para. 6.1.2.c and BT SIN227.
Configures modem standard to be used
for CLI delivery.
FSK follows ring burst as per Bellcore
GR-30-CORE and SR-TSV-002476
Clears any saved digits
n = MSN (up to 23 digits)
Country code is set to UK by default
n = country code
0 = UK
1 = Belgium
2 = Rest of Europe
Incoming calls on any channel are
accepted (provided other parameters
are valid eg MSN).
Where n = 1 or 2 for the appropriate
channel.
13
Disabled
n/a
Clear
n/a
UK
n/a
No channel
map
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ISDN Data and Telephony Protocol Engine (inc. X.25)
Configuration
Sequence
S95S#
S95S1#
Name
Description
Disable Calling Party No.
transmit
Outgoing call SETUP messages do not
contain any Calling Party Number
Information Elements.
Outgoing call SETUP messages
contain Calling Party Number
Information Element with number set to
saved MSN (if a number is present).
Prevents digits being transmitted to the
POTS port upon call connection.
Upon connection of a call on the POTS
port, if there was a Called Party
Number Information Element present in
the incoming call setup message, the
digits are sent as DTMF tones to the
POTS port.
Once the CMX228 is de-activated it
stays de-activated until the network reactivates it or an outgoing call needs to
be made.
The CMX228 checks to see if the ISDN
line is activated and Layer 2
communications can be made. It then
sets the ILFI pin accordingly.
Resets all of the configuration variables
back to their default values.
Enable Calling Party No.
transmit
S96S#
Disable DDI transmit
S96S1#
Enable DDI transmit
S97S#
Disable line failure
detection
S97S1#
Enable line failure
detection
S9SS1234567890#
CMX228
Initialise all
configurations.
Default
n/a
Enabled
n/a
Disabled
n/a
Disabled
n/a
The extent to which full CLI information is delivered to the POTS port will depend upon the CLI
facilities which have been implemented on the ISDN network.
Once the ‘S’ has been recognised, each digit pressed is then checked for validity as a configuration
sequence. If any digit pressed is not a valid configuration digit, all digits pressed so far will be
transmitted to the network in INFORMATION messages as Keypad Information Elements, until a ‘#’ is
entered (with the exception of ‘S#’ being entered, see Keypad Operation below). If the first four digits
received are a valid configuration sequence then the configuration mode is entered. When a valid
configuration has been completed the CMX228 will send a single DTMF tone to the POTS port. If a
valid configuration sequence is received but subsequent digits are invalid, then subsequent digits
entered will be ignored and two DTMF tones will be sent to the POTS port.
If the port goes on-hook part way through configuration, it will cause any digits received so far to be
ignored. Configurations can be performed consecutively with the exception of the test function (where
the attached handset must be replaced immediately after the configuration has been audibly signalled
to the POTS port). All configurations entered will be retained after a power-down as they are stored in
the external EEPROM.
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1.5.5
CMX228
POTS Operation
1.5.5.1 Keypad Operation
The CMX228 supports ISDN keypad messages for control of Network Supplementary services either
before or during call establishment. When dialling a number (ie off-hook and dial tone audible on
POTS port), or if a call has been disconnected by the network but the POTS port has not yet gone onhook, any keypad string entered will be sent to the network as ‘Keypad Information Elements’ within
INFORMATION messages. Keypad strings are defined as the following sequences of digits, with the
exception of the configuration strings defined in the previous section:
S...#
S#...#
#...#
When a call is connected, pressing the recall key results in all subsequent key presses being sent to
the network as ‘Keypad Information Elements’ within INFORMATION messages, until the handset is
replaced. The tones generated by the key presses are also passed down the B-channel, so the
remote user will be able to hear them.
1.5.5.2 Incoming POTS Calls
An incoming POTS call is identified by the Bearer Capability Information Element of the SETUP
message being set to ‘Speech' or ‘3.1 kHz Audio’. The call will be routed to the POTS port if it
satisfies the following three conditions:
• The port is on-hook.
• The MSN saved for the port matches the Called Number in the incoming SETUP message, or
no MSN is specified for the port, or there is no Called Number in the SETUP message. See
section 1.5.3.5 for details of POTS port MSN selection.
• The ISDN B-channel on which the call is placed (as indicated in the SETUP message) is
compatible with the channel mapping configuration for the port. See section 1.5.3.6 for details
of POTS port channel mapping selection.
When the call is routed to the port, the ringing signal for that port will be applied by means of the
RINGP1 and RINGN1 pins.
The call is answered when the port with ringing signal goes off-hook. The ringing signal is then
stopped and the ISDN call is connected to that port.
1.5.5.3 Outgoing POTS Calls
Outgoing calls are initiated when the POTS port goes off-hook. An ISDN SETUP message is sent to
the network with the Bearer Capability Information Element set to 'Speech'. The dial tone presented by
the network on that ISDN B-channel which was selected by channel mapping (see section 1.5.3.6), will
be routed to the POTS port.
When DTMF tones are received from the POTS port, they are sent to the network either as Called
Party Number or Keypad Information Elements. Keypad Information Elements are discussed in
section 1.5.5.1.
Receipt of a valid DTMF tone will prompt its conversion to IA5 coded digits, as shown in the following
table (IA5 hex digits are in brackets). If the first valid digit to be received is a ‘S’ then the configuration
mode is entered and subsequent digits will be monitored and saved as indicated in section 1.5.4.1. If
the first tone received is not a ‘S’ or ‘#’ (see section 1.5.5.1) that digit and all subsequent digits will be
passed to the network in an INFORMATION message as a Called Party Number Information Element.
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Digits received before the network has returned the SETUP ACK message are saved. Upon receipt of
the SETUP ACK any saved digits will be transmitted.
The DTMF tone mapping is as shown below:
Low Group
(Hz)
697
770
852
941
High Group (Hz)
1336
2 (32)
5 (35)
8 (38)
0 (30)
1209
1 (31)
4 (34)
7 (37)
S (2A)
1477
3 (33)
6 (36)
9 (39)
# (23)
1633
A (not used)
B (not used)
C (not used)
D (not used)
Once the network has indicated that the full number has been received, no further digits will be sent to
the network. All tones and announcements from the network (eg ringing, NU, busy etc) and audio (if
the call is connected) will be routed to the POTS port, until that port goes on-hook.
1.5.5.4 Connected Calls
Once a call is connected to the analogue port, whether it was incoming or outgoing, a LED indicator
pin is set high to indicate that the call is connected. See section 1.5.9.1 for details of the LED
indicator pins. Once the call is disconnected, either by receipt of a DISCONNECT message from the
network or an on-hook indication, that LED indicator pin is set low.
During a call, if a Recall (ie a line break of appropriate length) is received from the POTS port, the
CMX228 will start to look for DTMF tones received on the POTS port. Any tones received will then be
sent to the network in ISDN INFORMATION messages, as Keypad Information Elements.
1.5.5.5 Call Clearing
The call is cleared either by the port going on-hook or by the ISDN network. Note that the ISDN Bchannel which was being used is not released until the POTS port has gone on-hook.
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1.5.6
CMX228
Data Configuration
1.5.6.1 Hayes Command Set
The following Hayes commands are supported:
A
- Answers a call
D
- Dial
E
- Echo Hayes commands or not
H
- Hang-up
I3
- Firmware part number
Q
- Result code display
V
- Result code form
X
- Result code set
&C
- Carrier detect
&D
- Data terminal ready
&F
- Load factory default
&K
- Flow control
&V
- View active and stored profiles
&Z
- Store directory number
Valid Hayes commands are responded to with an 'OK' result code. Invalid commands are rejected with
an 'ERROR' result code.
If when entering an AT command, no command or register name suffix is supplied, a suffix of zero is
assumed. If when changing a register value, no value is supplied a value of zero or an empty string is
assumed: eg ATS0=<CR> is equivalent to ATS0=0<CR>.
If a data call is active when a command is entered, the command will be processed. The ATO
command will respond ‘OK’, but will not then enter the data state: it will stay in the command state.
Where commands set a parameter, these are saved in external EEPROM if they are entered correctly.
The CMX228 will auto-baud and auto-parity on Hayes commands at the following speeds:
9600 bps
19200 bps
38400 bps
57600 bps
115200 bps
The auto-bauding process looks for the characters ‘AT’ or ‘at’ either as 8 bits no parity or 7 bits even,
or odd, parity. An error in the auto-bauding process results in auto-bauding being restarted.
After auto-bauding successfully, the CMX228 waits to receive a complete Hayes command line before
processing it. Embedded spaces are ignored and the case (upper or lower) of characters after the
‘AT’ does not matter. The command line is terminated by <CR>, by 250 characters (not including the
‘AT’) or by a time-out (from successful auto-bauding on an ‘AT’) of 180 seconds.
All characters in the Hayes command, including the ‘AT’ and <CR> terminator are echoed (if E1 is set)
by the CMX228 as they are sent by the DTE.
Receipt of a back space will cause the CMX228 to send a "back space, space, back space" sequence
of characters to the DTE to allow the terminal to clear its screen of the last character. Also the last
character received will be discarded unless the last characters received were the ‘AT’ used for autobauding, ie the ‘AT’ is never deleted.
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The escape sequence ‘+++’ (with Guard Time = 1s before and after the sequence) will cause the
CMX228 to enter the command state from the data state and to return an ‘OK’ response. Sending an
ATO command will be ignored, ie the CMX228 remains in the command state.
The following is a more detailed description of the Hayes commands listed above:
A (Answer)
Format: ATA<CR>
Causes the CMX228 to answer an incoming data call, by sending a CONNECT message to the
network. If a CONNECT ACK is received the CMX228 enters the data state after returning a
‘CONNECT XXX’ result code to the DTE on the RS232 port (where the XXX is the speed in baud). If
a RELEASE, RELEASE COMPLETE or DISCONNECT message is received a ‘NO CARRIER’ result
code is returned. The command is not valid if there is no incoming call and it will return ‘ERROR’.
D (Dial)
Format: ATD{DN}<CR>
Format: ATDT{DN}<CR>
Format: ATDP{DN}<CR>
{DN} is a directory number of up to 23 ASCII characters from 0..9, S and #. This form of the ATD
command causes an outgoing SETUP message to be sent to the network with a Called Party Number
Information Element which contains the digits included in the command. Any commands that follow
this command are ignored.
If the CMX228 receives any character from the DTE after an ATD command, which causes a SETUP
message to be sent to the network, and before the call is connected, the attempt to make a call is
abandoned, ie a DISCONNECT message will be sent to the network and a ‘NO CARRIER’ result code
returned.
Calls are established with the D command, irrespective of the state of the DTR pin. The result code
response is either:
'CONNECT'
'NO CARRIER'
'NO DIALTONE'
'BUSY'
- call successful. The CMX228 will automatically enter the data state.
- call rejected by the remote user or the network
- ISDN link down
- remote user busy and other causes
Calls are cleared in the following way:
(i) The remote end or network clears the call by sending a DISCONNECT message or the ISDN
line fails/is removed: 'NO CARRIER' is sent to DTE.
(ii) DTR is dropped (with a de-bounce period of 50ms) by DTE causing the CMX228 to send a
DISCONNECT message to the network and enter the disconnect state, awaiting a RELEASE
COMPLETE from the network. The CMX228 sends the 'OK' response when clearing of the ISDN
call is complete ie RELEASE and RELEASE COMPLETE messages have been transmitted
across the network, (dependant upon the state of &D command).
(iii) The DTE issues the escape sequence ‘+++ ‘(with Guard Time = 1s before and after the
sequence), receives an 'OK' response and then issues the Hang-up command (see section on H
command below). The CMX228 sends the 'OK' response when clearing of the ISDN call is
complete.
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Incoming calls are indicated by a 'RING' result code. The call is automatically answered if S0 = 1 or
more. If S0 = 0 an ATA command must be entered, then a CONNECT message is sent to the
network.
E (Echo)
Format: ATEn<CR>
Suffix n
0
1 (default)
Description
Echo off
Echo on
This command tells the CMX228 whether or not to echo the characters received from the DTE when
in command mode. When echo is on, all non control characters received from the DTE are echoed
back to it.
H (Hang-up)
Format: ATH<CR>
Causes the CMX228 to clear the data call in progress. The command is not valid if there is no data
call in progress but always returns an ‘OK’ result code. It is only valid in the command state when a
data call is in operation, when it will send a DISCONNECT message to the network. Upon receipt of
RELEASE, a RELEASE COMPLETE is transmitted to the network and ‘OK’ returned to the DTE.
I3 (Firmware Part Number)
Format: ATI3<CR>
Causes the CMX228 to return the part code and revision level to the DTE:
"CMX228: Vn.nn"
where n.nn = version number
Q (Result Code Display)
Format: ATQn<CR>
Suffix n
0 (default)
1
2
Description
Result codes enabled
Result codes suppressed
Result codes are suppressed when an incoming call is received,
otherwise enabled
V (Result Code Form)
Format: ATVn<CR>
Suffix n
0
1 (default)
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Description
Result codes sent as numbers (see Data Call Result Codes below)
Result codes sent as words. This instructs the CMX228 to send the
result codes as words or numbers to the DTE.
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X (Result Code Set)
Format: ATXn<CR>
Suffix n
0
1
2
3 (default)
4
Description
0...4
0...4, 12, 14, 18, 28, 31
0...4, 12, 14, 18, 28, 31
0...4, 6, 7, 12, 14, 18, 28, 31
0...4, 6, 7, 12, 14, 18, 28, 31
This command causes the CMX228 to limit the data call result codes used to a given set. See Data
Call Result Codes below for a list of codes and their meanings.
Data Call Result Codes
The data call result codes supported are:
Numbers
Words
0
'OK'
1
'CONNECT'
2
'RING'
3
'NO CARRIER'
4
'ERROR'
6
'NO DIALTONE'
7
'BUSY'
12
'CONNECT 9600'
14
'CONNECT 19200'
18
'CONNECT 57600'
28
'CONNECT 38400'
31
'CONNECT 115200'
&C (Carrier Detect)
Format: AT&Cn<CR>
Changes the operation of the RS232 DCD (Data Carrier Detect) signal.
Suffix n
0
1 (default)
Description
Ignore connection status, keep DCD high and LED3 pin low (ie ON).
DCD tracks the status of the data connection, raised when the call
is connected, lowered when cleared. LED3 pin tracks the inverse status
of the DCD pin (ie high when data connection is cleared).
&D (Data Terminal Ready)
Format: AT&Dn<CR>
Determines the CMX228 operation if DTR is lowered during a call.
Suffix n
0
2 (default)
Description
No action
B or D-channel data call is cleared and auto-answer is suspended until
DTR is raised again.
If &D2 is set and DTR is low when an incoming call is received, the call is accepted and Ring
Indication is sent to the DTE. If an incoming call has been accepted and &D2 is set when DTR is
lowered, the call is cleared.
&F (Load Factory Profile)
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Format: AT&F<CR>
Sets the following commands and registers to their default values.
It does not change the %A !B, !C registers or the &Z command.
Commands:
E
Q
V
X
&C
&D
Registers:
S0
S37
%B
%D
%E
%L
&K
Format: AT&F9<CR>
Sets all commands and registers to the default values and resets LED indicator and RS232 interface
pins accordingly.
&K (Flow Control)
Format: AT&Kn<CR>
Indicates the method of flow control to be used between the CMX228 and the DTE when in the data
state. There is no flow control when the CMX228 is in the command state.
Suffix n
0
3 (default)
Description
No flow control
Bi-directional RTS/CTS signals
Flow control is only active when in an active data call, ie not when dealing with Hayes commands.
Flow control is applied to the DTE in the following situations:
(i) The remote end signals flow control (the mechanism is protocol dependent).
(ii) Several buffers of data are held waiting transmission across ISDN.
Flow control is applied to the remote end (the mechanism is protocol dependent) if excessive data is
held pending transmission to the DTE, so as to prevent local buffer overflow.
&V (View Active/Stored Profiles)
Format: AT&V<CR>
Causes the CMX228 to display the following command and register values for the stored profile:
Commands:
E
Q
V
X
&C
&D
&K
&Z
Registers:
S0
S37
%A
!C
%E
%B
%D
%L
!B
&Z (Store Directory Number)
Format: AT&Z3={DN}<CR>
This command instructs the CMX228 to store a directory number. The stored directory number is then
used by the X.25 call setup as the ‘Calling NUA’.
A directory number consists of a string of characters from the set 0..9, S and #. The ‘=‘ character can
be omitted. Where a store number is entered, only the value 3 will give an ‘OK’ response. The
contents of the &Z directory number are displayed by using the &V0 command. Up to 20 digits can be
saved. The number must be in quotes. eg at&z3 =’12345’.
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1.5.6.2 Hayes Register Set
In addition to the commands, there are a group of registers for which data is entered in the following
format: AT{register}={value}<CR>. The following Hayes registers are supported:
S0
S37
%A2
%B0
%B1
%B2
%B3
%B13
%B18
%D0
%D1
%D2
%D3
%D9
%D10
%E8
%L3
%L4
%L10
!B1
!B2
!B3
!B5
!C4
!C5
!C6
!C7
!C8
- Number of rings on which to auto-answer
- Maximum rate adaption speed
- B/D-channel protocol
- X.25 receive window size
- X.25 transmit window size
- X.25 receive packet size
- X.25 transmit packet size
- X.25 NUI
- X.25 user data
- X.25 default receive window size
- X.25 default transmit window size
- X.25 default receive packet size
- X.25 default transmit packet size
- X.25 group number
- X.25 channel number
- V.120 MFO mode selection
- PAD forwarding character
- PAD idle timer
- PAD line folding
- LAPB T1 timer
- LAPB T4 timer
- LAPB N2 retry count
- X.25 LAPB active/passive
- B1-channel configuration
- B2-channel configuration
- Multiple Subscriber Numbering
- TEI selection
- ISDN Line Failure Detection enable/disable
The following is a more detailed description of the Hayes registers listed above:
S0 (Rings on Which to Auto-answer a Data Call)
Range
0 to 255
Default
0
Description
If set to 0 auto-answering will be disabled.
Any other value will cause one ‘RING’ result code to
be sent to the DTE after which the call is answered.
S37 (Maximum Rate Adaption Speed)
This forces the baud rate when handling incoming calls, to that defined by the S37 register contents,
provided auto-answer is set. Once a call is terminated the baud rate remains that set by the S37
register.
Value
0 (default)
9
12
13
18
31
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Rate (baud)
Same as last AT speed
9600
19200
38400
57600
115200
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%A2 (CSD Protocol)
Selects the protocol to be used for the circuit switched data calls. Note that %A2 cannot be changed
while a B or D-channel call is active.
Value
2 (default)
3
4
5
6
15
20
Description
V.120 Rate Adaption on B-channel.
Voice Calls.
X.25 Rate Adaption on B-channel.
X.25 packet calls on D-channel.
X.25 to a packet switched data network reached by a B-channel data
call. This involves a two stage call set up. Firstly a circuit switched call
must be established to the X.25 node, followed by a virtual call to an X.25
destination. The ATD command is used for both call requests.
PPP.
Transparent protocol.
1.5.6.2.1 X.25 Virtual Circuit Parameters
All %B registers can be read using the %Bn? command.
%B0 (X.25 Receive Window Size)
Defines the maximum number of X.25 packets that may be received before an acknowledgement is
sent.
Value
0 (default)
1 to 7
Description
Use the default value appropriate to the type of call, without negotiation,
see %D registers.
Negotiate the receive window size according to the value entered.
%B1 (X.25 Transmit Window Size)
Defines the maximum number of X.25 packets that may be transmitted before an acknowledgement is
expected. Use of the default value is recommended.
Value
0 (default)
1 to 7
Description
Use the default value appropriate to the type of call, without negotiation,
see %D registers.
Negotiate the transmit window size according to the value entered.
%B2 (X.25 Receive Packet Size)
Defines the maximum number of bytes that may be received in an X.25 packet.
Value
0 (default)
7
8
9
10
Description
Use the default value appropriate to the type of call, without negotiation,
see %D registers.
Negotiate for a maximum 128 bytes per packet.
Negotiate for a maximum 256 bytes per packet.
Negotiate for a maximum 512 bytes per packet.
Negotiate for a maximum 1024 bytes per packet.
%B3 (X.25 Transmit Packet Size)
Defines the maximum number of bytes that may be transmitted in an X.25 packet.
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Value
CMX228
Description
0 (default)
Use the default value appropriate to the type of call, without negotiation,
see %D registers.
7
Negotiate for a maximum 128 bytes per packet.
8
Negotiate for a maximum 256 bytes per packet.
9
Negotiate for a maximum 512 bytes per packet.
10
Negotiate for a maximum 1024 bytes per packet.
%B13 (Network User Identification String)
A maximum of 32 ASCII characters. The default value is an empty string. The Network User
Identification (NUI) string is used to identify the terminal to the packet switched network if necessary.
If there is at least one character present, the NUI is transmitted to the network when the call is
established.
%B18 (User Data)
Up to 12 ASCII characters. Default is an empty string. The X.25 user data field which is sent when the
X.25 call is established.
1.5.6.2.2 X.25 Parameters
All %D registers can be viewed using the %Dn? command.
%D0 (Default receive Window Size (Negotiated))
Defines the default maximum number of X.25 packets that may be received before an
acknowledgement is sent, only in use if %B0=0.
Range
1 to 7
Default
2
Description
Default receive window size.
%D1 (Default Transmit Window Size (Negotiated))
Defines the default maximum number of X.25 packets that may be transmitted before an
acknowledgement is expected, only in use if %B1=0.
Range
1 to 7
Default
2
Description
Default transmit window size.
%D2 (Default Receive Packet Size (Negotiated))
Defines the default maximum number of bytes that may be received in an X.25 packet, only in use if
%B2=0.
Value
7
8 (default)
9
10
Description
Maximum 128 bytes per packet.
Maximum 256 bytes per packet.
Maximum 512 bytes per packet.
Maximum 1024 bytes per packet.
%D3 (Default Transmit Packet Size (Negotiated))
Defines the default maximum number of bytes that may be transmitted in an X.25 packet, only in use if
%B3=0.
Value
7
8 (default)
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Description
Maximum 128 bytes per packet.
Maximum 256 bytes per packet.
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9
10
CMX228
Maximum 512 bytes per packet.
Maximum 1024 bytes per packet.
%D9 (Group Number)
Defines the group number used in outgoing call setup messages.
Range
0 to 7
Default
4
Description
Group number.
%D10 (Channel Number)
Defines the channel number used in outgoing call setup messages.
Range
0 to 255
Default
0
Description
Channel number.
1.5.6.2.3 V.120 Parameters
%E8 (Multiple Frame Operation Mode Selection)
In Multiple Frame Operation (MFO) mode, frames are acknowledged and retransmitted if errors occur.
Value
0
1(default)
Description
MFO mode on.
MFO mode off.
1.5.6.2.4 X.25 PAD Parameters
All %L registers can be viewed using the %Ln? command.
%L3 (Selection of Data Forwarding Characters)
This register is used to specify the characters which, when received from the DTE, will cause the
current packet of data to be transmitted. If set to zero, the packet is not transmitted until either the idle
timer (%L4) expires, or the packet becomes full (%B3). The values listed below may be added
together to combine the character sets indicated. The characters are as described in the ASCII
character set.
Value
0 (default)
1
2
4
8
16
32
64
Description
None.
A to Z, a to z and 0 to 9.
CR.
ESC, BEL, ENQ and ACK.
DEL, CAN and DC2.
ETX and EOT.
HT, LF, VT and FF.
NUL, SYN, ETB, EM, SUB, FS, GS, RS, and US.
%L4 (Idle Timer)
Range
Default
Description
0 to 40
0
Specifies the duration of the timer (in units of 1/20
second) that, when it expires, causes the contents of
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the current packet to be forwarded. If set to zero, there
is no timed forwarding.
%L10 (Line Folding)
Range
0 to 255
Note:
Default
0
Description
Specifies the line length required. When the specified
number of characters have been sent to the DTE a
carriage return and line feed are sent to ensure that lines
do not exceed the required length. A value of zero
disables line folding.
If %L3 and %L4 are both 0, characters will be forwarded as they become available.
1.5.6.2.5 B Channel LAPB Parameters
All !B registers can be viewed using the !Bn? command.
!B1 (LAPB T1 Timer)
Range
1 to 255
Default
3
Description
Sets the value, in seconds, of the LAPB T1 timer.
Default
15
Description
Sets the value, in seconds, of the LAPB T3 timer.
!B2 (LAPB T3 Timer)
Range
1 to 255
!B3 (LAPB N2 Retry Count)
Range
1 to 255
Default
4
Description
Sets the number of times the LAPB protocol will retry
sending before giving up and applying recovery
procedures.
!B5 (Active/Passive)
Value
0 (default)
1
Description
X.25 is Active ie initiates link initialisation.
X.25 is Passive and waits for the network to initialise the link.
1.5.6.2.6 Basic Configuration Parameters
!C4 (B1 Channel Mapping)
Enables data calls to be made and accepted on the B1-channel. If !C5 is set to 0 the outgoing call
SETUP message will contain a Channel Identification Information Element set to B1-channel only.
Value
0
4 (default)
Description
Incoming data calls on the B1-channel are rejected with ‘channel not
acceptable’ as the cause.
Incoming data calls on the B1-channel are accepted provided no other
data call is present.
!C5 (B2 Channel Mapping)
Enables data calls to be made and accepted on the B2-channel. If !C4 is set to 0 the outgoing call
SETUP message will contain a Channel Identification Information Element set to B2-channel only.
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Value
0
4 (default)
Note:
CMX228
Description
Incoming data calls on the B2-channel are rejected with ‘channel not
acceptable’ as the cause.
Incoming data calls on the B2-channel are accepted provided no other
data call is present.
If both !C4 and !C5 =0 no data calls will be made or received.
!C6 (MSN Directory Number)
Also refer to ISDN MSN (section 1.5.3.5).
If there is a number saved in this register upon receipt of an incoming data call, the CMX228 will check
for the presence of a Called Party Number Information Element. If present it will compare the number
with that saved in the !C6 register. If they match, the call will be accepted, ie a ‘RING’ indication (RI
pin is raised, then lowered after 3s) is returned to the DTE. If the Called Party Number Information
Element and saved MSN do not match, the call is ignored. The command is entered as follows:
AT!C6=“nnnn”<CR>
if no digits are present within the quotes, the MSN is cleared.
Up to 23 digits may be entered.
!C7 (TEI selection)
Selects the fixed or negotiated TEI used on the ISDN link. Note that the value of !C7 only takes effect
when the ISDN interface goes from de-activated to activated.
Value
0-63
64 (default)
Description
Fixed TEI, 0 to 63.
Negotiated TEI.
!C8 (ISDN Line Failure Detection enable/disable)
Enables or disables Line Failure Detection. (Refer to section 1.5.3.3).
Value
0
1 (default)
1999 Consumer Microcircuits Limited
1999 Chiron Technology Limited
Description
Line Failure Detection disabled.
Line Failure Detection enabled.
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D/228/1
ISDN Data and Telephony Protocol Engine (inc. X.25)
1.5.7
CMX228
Data Operation
1.5.7.1 Incoming B-Channel Data Calls
All incoming data calls which have valid channel use and MSN are directed to the data port and cause
‘RING’ followed by the digits of the calling party number and the calling party subaddress (if received
in the SETUP message) to be returned to the DTE. The Ring Indicator (RI) pin is also raised, then
lowered after 3s. ‘RING’ text and the raising of RI for 3s is repeated every 6s until the call is cleared
or answered, provided S0=0. If S0=1 then only one RING will appear at the DTE and the RI line will
be raised only once, as a CONNECT message will be sent to the network.
1.5.7.2 Outgoing B-Channel Data Calls
Outgoing calls are requested specifying either B-channel unless channel mapping is enabled via !C4
and !C5 registers. The SETUP message is sent without High Layer Compatibility or Low Layer
Compatibility and with the following Bearer Capability:
CCITT coding standard
Unrestricted digital
Circuit mode
64k information transfer rate
If there is a saved MSN in !C6 register all outgoing call SETUP messages will contain the saved
number in a Calling Party Number Information Element.
1.5.7.3 X.25 Data Calls on the D-Channel
When D-channel data is selected (via Hayes register %A2), B-channel data calls cannot be made.
Any incoming B-channel data calls will be rejected with ‘Busy’.
1.5.7.4 Connected Calls
Once a call is connected to the digital port, whether it was incoming or outgoing, the DCD pin is set
high to indicate that the call is connected (providing &C0 command is not given). If the DCD pin is set
high, the LED3 pin will be set low.
1.5.7.5 Call Clearing
The call is cleared either by the ATH command or by the ISDN network. When the call has been
cleared, the DCD pin is set low and the LED3 pin is set high (providing the &C0 command is not
given).
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D/228/1
ISDN Data and Telephony Protocol Engine (inc. X.25)
1.5.8
CMX228
Application Programmer's Interface
Details of this will be supplied to customers under a Non-Disclosure Agreement.
The following Memory Map indicates the main code areas used on the CMX228:
Function
Start Hex Address
End Hex Address
Code Space
External RAM
API area
AMD79C30
ISDN Interface Chip
PSB21525
HDLC Driver Chip
Reserved
000 000
020 000
0C0 000
0F0 000
01F FFF
03F FFF
0EF FFF
0F0 0FF
0F0 100
0F0 1FF
0F0 200
0FF FFF
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D/228/1
ISDN Data and Telephony Protocol Engine (inc. X.25)
1.5.9
CMX228
Hardware Description
1.5.9.1 LED Status Indicators (LED1 to LED9, and ILFI)
LED1 (HK1) is low when the POTS port is off-hook, high when on-hook.
LED2 (AA) indicates that register S0 has been set to 1 or more when low and set to 0 when high
(RS232 Auto Answer indication).
LED3 (DCD) is low when a call is connected via the RS232 port (if &C0 is set to '1'), high when a call
is not connected to this port.
LED4 (RTS) is low if RTS on the RS232 port is active and vice versa, indicating flow control (RS232
Ready To Send).
LED5 (RXD) is low if data is being sent to the DTE (RS232).
LED6 (TXD) is low if data is being received from the DTE (RS232).
LED7 (DTR) is low if the de-bounced DTR line on the RS232 port is active and vice versa.
LED8 (AR) is pulsed high and low until the ISDN line is activated, when it remains low constantly.
LED9 (CN1) is high when the POTS port is connected to the ISDN network, low when not connected.
ILFI is high when an ISDN Link Failure is Indicated, low when the link is operational.
The functions of the LED and ILFI indicators are set out in the table below:
Pin No.
12
13
14
15
16
17
18
19
21
54
Designation
LED1
LED2
LED3
LED4
LED5
LED6
LED7
LED8
LED9
ILFI
1999 Consumer Microcircuits Limited
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POTS port
Off-Hook
~
~
~
~
~
~
ISDN Line Activated
Call Connected
ISDN Line Failure
Indicator
30
RS232 port
~
Auto-Answer
Carrier Detect
Ready to Send
Receive Data
Transmit Data
Data Terminal Ready
ISDN Line Activated
~
ISDN Line Failure
Indicator
D/228/1
ISDN Data and Telephony Protocol Engine (inc. X.25)
1.6
Application Notes
1.6.1
General
CMX228
The CMX228 is intended for use as part of an ISDN chipset. The CML recommended hardware
implementation contains the following elements (refer to Figure 3):
‘S’ bus interface via RJ45 socket.
RJ11 analogue telephone socket and analogue circuitry.
ISDN line transformer.
AMD79C30 S-interface controller.
Single asynchronous RS232 interface via 9-way or 25-way D-type connector.
64K bytes external RAM.
16K Non-volatile memory.
Ten processor controlled LED indicator signals.
HDLC drivers for the 2 ISDN B-channels, both channels can be used for data transfer.
Figure 3 Application Block Diagram
1.6.2
Approvals
The firmware and finite state machine embedded in the CMX228 have been used in products which
have gained ETSI CTR3 approval.
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D/228/1
ISDN Data and Telephony Protocol Engine (inc. X.25)
1.7
Performance Specification
1.7.1
Electrical Performance
CMX228
1.7.1.1 Absolute Maximum Ratings
Exceeding these maximum ratings can result in damage to the device.
Supply (AVDD - AVSS), (DVDD0 - DVSS0), (DVDD1 - DVSS1)
Voltage on any pin to AVSS, DVSS0 or DVSS1
Current into or out of any VDD or VSS pin
Current into or out of any other pin
S1 Package (QFP)
Total Allowable Power Dissipation at Tamb = 25°C
... Derating
Storage Temperature
Operating Temperature
Min.
-0.3
-0.3
-30
-20
Max.
7.0
VDD + 0.3
+100
+10
Units
V
V
mA
mA
Min.
-55
-40
Max.
1300
17
+125
+85
Units
mW
mW/°C
°C
°C
Min.
2.7
Max.
5.5
Units
V
-40
-100
+85
+100
°C
ppm
1.7.1.2 Operating Limits
Correct operation of the device outside these limits is not implied.
Notes
Supply: (AVDD - AVSS), (DVDD0 - DVSS0),
and (DVDD1 - DVSS1)
Operating Temperature
32 MHz Xtal Frequency Tolerance
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D/228/1
ISDN Data and Telephony Protocol Engine (inc. X.25)
CMX228
1.7.1.3 Operating Characteristics
Details in this section represent design target values and are not currently guaranteed.
For the following conditions unless otherwise specified:
Xtal Frequency = 32MHz ± 100ppm, AVDD = DVDD0 = DVDD1 = 3.0V to 5.0V, Tamb = - 40°C to +85°C.
DC Parameters
IDD (total, operational)
IDD (total in HALT mode)
IDD (total in IDLE mode)
Notes
Min.
Typ.
Max.
Units
1
1
1
−
−
−
25.0
13.0
−
45.0
26.0
12.0
mA
mA
mA
70%
−
-10.0
VDD -1.0
−
−
−
−
−
−
−
−
−
30%
+10.0
−
400
10
VDD
VDD
µA
V
mV
µA
10
10
−
−
31.2468
−
−
−
−
−
125
125
10
10
31.2531
ns
ns
ns
ns
ns
Digital Interface
Input logic "1" level
Input logic "0" level
Input leakage current (Vin = 0 to DVDD)
Output logic "1" level (lOH = -2mA)
Output logic "0" level (lOL = 2mA)
Input or Output leakage current (Vout = VDD)
Xtal/Clock Input
'High' pulse width (tWXH)
'Low' pulse width (tWXL)
Risetime (tXR)
Falltime (tXF)
Period (tCYK)
Notes:
2
2
2
2
2, 3
1. Not including any current drawn by external circuitry.
2. Timing for an external input to the XTAL pin.
3. A fundamental cut crystal is recommended.
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D/228/1
ISDN Data and Telephony Protocol Engine (inc. X.25)
CMX228
1.7.1.3 Operating Characteristics (continued)
Timing Diagrams
Figure 4 External Memory Access Timing
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D/228/1
ISDN Data and Telephony Protocol Engine (inc. X.25)
CMX228
Timing Diagrams (continued)
Figure 5 Bus Hold Timing
Figure 6 Miscellaneous Timing
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D/228/1
ISDN Data and Telephony Protocol Engine (inc. X.25)
CMX228
AC Timing Parameters (continued)
For the following conditions unless otherwise specified:
Xtal Frequency = 32MHz, AVDD = DVDD0 = DVDD1 = 3.0V to 5.0V, Tamb = - 40°C to +85°C.
Read/Write operation (1/2)
Parameter
Symbol
Conditions
Address setup time
tSAST
VDD = +5.0V ± 10%
ASTB high-level width
tWSTH
VDD = +5.0 V ± 10%
Address hold time to (ASTB↓)
tHSTLA
VDD - +5.0 V ± 10%
Address hold time (to RD↑ )
Delay from address to RD↓
tHRA
tDAR
VDD = +5.0V ±10%
Address float time (to RD↓)
Delay from address to data input
tFRA
tDAID
VDD = +5.0V ±10%
Delay from ASTB↓ to data input
tDSTID
VDD = +5.0V ± 10%
Delay from RD↓ to data input
tDRID
VDD = +5.0 V ± 10%
Delay from ASTB↓ to RD↓
Data hold time (to RD↑)
Delay from RD↑to address active
tDSTR
tHRID
tDRA
VDD = +5.0 V ± 10%
After program is read
After program is read
VDD = +5.0 V ± 10%
After data is read
After data is read
Delay from RD↑ to ASTB↑
RD low-level width
tDRST
tWRL
VDD = 5.0 V ± 10%
Address hold time (to WR↑)
Delay from address to WR↓
tHWA
tDAW
VDD = +5.0V ± 10%
Delay from ASTB↓ to data output
tDSTOD
VDD = +5.0V ± 10%
Delay from WR↓ to data output
Delay from ASTB↓ to WR↓
tDWOD
tDSTW
Where:
Min.
Max.
Units
(0.5 + a) T - 15
(0.5 + a) T - 31
(0.5 + a) T - 17
(0.5 + a) T - 40
0.5T - 24
0.5T - 34
0.5T - 14
(1 + a) T - 9
(1 + a) T - 15
−
−
−
−
−
−
−
0.5T - 9
0
−
−
−
−
−
−
−
−
−
0
(2.5 + a + n) T - 37
(2.5 + a + n) T - 52
(2 + n) T - 40
(2 + n) T - 60
(1.5 + n) T - 50
(1.5 + n) T - 70
−
−
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
0.5T - 8
−
ns
0.5T - 12
−
ns
1.5T - 8
−
ns
1.5T - 12
0.5T - 17
(1.5 + n) T - 30
(1.5 + n) T - 40
0.5T - 14
(1 + a) T - 5
(1 + a) T - 15
−
−
−
0.5T - 9
−
−
−
−
−
−
−
0.5T + 19
0.5T + 35
0.5T - 11
−
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
T = tCYK (system clock cycle time)
a = 1 (during address wait), otherwise, 0
n = Number of wait states (n = 2)
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D/228/1
ISDN Data and Telephony Protocol Engine (inc. X.25)
CMX228
Read/Write operation (2/2)
Parameter
Symbol
Conditions
Data setup time (to WR↑)
tSODW
VDD = +5.0 V ± 10%
Data hold time (to WR↑)Note 1
tHWOD
VDD = +5.0V ± 10%
Delay from WR↑ to ASTB↑
WR low-level width
tDWST
tWWL
VDD = +5.0V ± 10%
Min.
(1.5 + n) T - 30
(1.5 + n) T - 40
0.5T - 5
0.5T - 25
0.5T - 12
(1.5 + n) T - 30
(1.5 + n) T - 40
Max.
−
−
−
−
−
−
−
Units
ns
ns
ns
ns
ns
ns
ns
Note 1: Hold time includes the time during which VOH1 and VOL1 are held under the load conditions of CL = 50 pF and RL = 4.7 kΩ.
Bus Hold timing
Parameter
Symbol
Conditions
Delay from WAITN↑ to float
Delay from WAITN↑ to STN↑
tDHQHHAH VDD = +5.0 V ± 10%
Delay from float to STN↑
Delay from WAITN↑ to STN↓
tDCFHA
tDHQLHAL
VDD = +5.0 V ± 10%
tDHAC
VDD = +5.0 V ± 10%
Delay from STN↓ to active
tFHQC
Min.
−
−
−
−
−
−
1T - 20
1T - 30
Max.
(6 + a + n) T + 50
(7 + a + n) T + 30
(7 + a + n) T + 40
1T + 30
2T + 40
2T + 60
−
−
Units
ns
ns
ns
ns
ns
ns
ns
ns
Miscellaneous timing
Parameter
Symbol
Conditions
Min.
Max.
nT
0.5 tCYCL- 10
0.5 tCYCL- 20
0.5 tCYCL- 10
0.5 tCYCL- 20
−
−
−
−
−
−
−
−
−
10
20
10
20
ns
ns
tWNIL
tWNIH
10
10
−
−
µs
µs
tWRSL
tWRSH
10
10
−
−
µs
µs
ASTB cycle time
ASTB low-level width
tCYCL
tCLL
VDD = +5.0 V ± 10%
ASTB high-level width
tCLH
VDD = +5.0 V ± 10%
ASTB rise time
tCLR
VDD = +5.0 V ± 10%
ASTB fall time
tCLF
VDD = +5.0 V ± 10%
NMI low-level width
NMI high-level width
RSTN low-level width
RSTN high-level width
Where:
Units
ns
ns
ns
ns
T = tCYK (system clock cycle time)
a = 1 (during address wait), otherwise, 0.
n = Number of wait states (n = 2).
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D/228/1
ISDN Data and Telephony Protocol Engine (inc. X.25)
1.7.2
CMX228
Packaging
Figure 7 QFP Mechanical Outline: Order as part no. CMX228S1
Handling precautions: This product includes input protection, however, precautions should be taken to prevent device damage from
electro-static discharge. CML does not assume any responsibility for the use of any circuitry described. No IPR or circuit patent
licences are implied. CML reserves the right at any time without notice to change the said circuitry and this product specification. CML
has a policy of testing every product shipped using calibrated test equipment to ensure compliance with this product specification.
Specific testing of all circuit parameters is not necessarily performed.
Oval Park - LANGFORD
MALDON - ESSEX
CM9 6WG - ENGLAND
Telephone: +44 (0)1621 875500
Telefax:
+44 (0)1621 875600
e-mail:
[email protected]
http://www.cmlmicro.co.uk