CMLMICRO CMX625D5

CMX625
ISDN TA POTS Interface
D/625/2 July 2001
Advance Information
Features
Applications
• SPM and Ringing Voltage Generators
• ISDN NTUs with Analogue Ports
• Integrated DTMF Decoder/Encoder
• ISDN Line Cards
• V.23/Bell 202 FSK/Tone Generator
• Wireless Local Loop Termination Cards
• Selectable A-Law/µ-Law PCM Codec
• ISDN Terminals with Additional POTS Ports
• IOM-2 Interface Terminal Mode and
• PC based ISDN Cards with Telephone Ports
Non-Terminal Mode (Line Card Mode)
• Billing/SPM Systems
IOM is a trademark of Siemens AG
1.1
Brief Description
The CMX625 is an integrated telecom tone generator, DTMF encoder/decoder and PCM Codec-Filter
designed for ISDN interfaces, Wireless Local Loop and other digitised speech systems. The tone
generator covers a wide range of pre-programmed tones used in analogue phone systems. Three outputs
are provided: Ringing signals, In-band tones or FSK data, and 12kHz/16kHz Subscriber Metering pulses.
The PCM Codec-Filter performs voice digitisation and reconstruction and incorporates band limiting and
smoothing with selectable A-law or µ-law companding following ITU-T recommendation G.711. The
DTMF decoder presents the serial bus interface with the DTMF dialling information received from the
telephone user and the tone generator sends the appropriate DTMF tones to this POTS interface. Other
tone standards supported are: Fax and Modem ‘answer’ and ‘originate’, ITU-T ‘R1’ and ‘R2’ signals, dual
tones for CIDCW and 'On-Hook' signalling systems and sufficient tones for simple melody generation.
®
The IOM -2 (ISDN Oriented Modular revision 2) industry standard serial bus provides the digital interface
to other telecommunications ICs and supports both Terminal and non-Terminal (or Line Card) modes.
The CMX625 is compatible with the CMX635 ISDN Subscriber Processor and can be used to provide the
additional POTS port. It is available in both DIP and SSOP packages.
 2001 Consumer Microcircuits Limited
ISDN TA POTS Interface
CMX625
CONTENTS
Section
Page
1.1
Brief Description ..................................................................................... 1
1.2
Block Diagram ......................................................................................... 3
1.3
Signal List ................................................................................................ 4
1.4
External Components ............................................................................. 6
1.5
General Description ................................................................................ 7
1.5.1 IOM™-2 Serial Bus Interface ..................................................... 7
1.5.2 Terminal Mode (TE).................................................................... 8
1.5.3 Non-Terminal Mode (non-TE) ................................................. 10
1.5.4 Monitor Channel Handshake Protocol................................... 11
1.5.5 Monitor Channel Identification Command ............................ 13
1.5.6 PCM Codec-Filter ..................................................................... 13
1.5.7 Rx Input Amplifier .................................................................... 14
1.5.8 Tx Output Buffer ...................................................................... 14
1.5.9 Tone/FSK Encoder and Tone Encoder .................................. 14
1.5.10 SPM Generator ......................................................................... 17
1.5.11 Transmit Signal Control .......................................................... 17
1.5.12 Tx UART .................................................................................... 18
1.5.13 DTMF Tone Decoder ................................................................ 19
1.5.14 Register Set .............................................................................. 20
1.5.15 Programming the CMX625 ...................................................... 20
1.5.16 Glossary.................................................................................... 22
1.6
Application Notes.................................................................................. 23
1.6.1 Telecom Tones ......................................................................... 23
1.7
Performance Specification................................................................... 27
1.7.1 Electrical Performance ............................................................ 27
1.7.2 Packaging ................................................................................. 33
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D/625/2
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3
STATUS
& IRQ
STATUS
Register
VSS
PCM ADC
A-law / -law
SA1
ROM
BUS
PCM Codec
Registers
Analogue Loopback
Tone / FSK
Encoder
Tx UART
SA0
VBIAS
STATUS
& IRQ
DTMF
Tone
Decoder
TE/NTE
IOM®-2 Serial Bus Interface
DU
Tone Encoder
Enable
Rx Input
Amplifier
DD
SETUP &
MODE Registers
DCL
VDD
RXO
RXP
RXN
FSC
DS
PCM DAC
A-law / -law
Tx Signal
Control
Vbias
SPM Generator
Interrupt
Generator
SA2
Enable
Tx Output
Buffer
IRQN
DAC OUT
TONEFSK
RING
TXO
TXON
TXN
SPM
1.2
FSK / TONES
Tx Registers
RESET
ISDN TA POTS Interface
CMX625
Block Diagram
Figure 1 Block Diagram
D/625/2
ISDN TA POTS Interface
1.3
CMX625
Signal List
CMX625
D5/P4
Pin No.
Name
Type
1
FSC
I/P
The IOM-2 Frame Synchronisation Clock. This is an 8kHz
clock indicating the start of the frame. FSC is generated
by the upstream device. See section 1.5.1, 1.5.2 and
1.5.3.
2
DCL
I/P
The IOM-2 Data Clock. It is used to clock data on and off
the bus and operates at 1.536MHz for Terminal mode
(TE) or 4.096MHz for non-Terminal mode (non-TE or Line
Card mode). DCL is generated by the upstream device.
When the bus is deactivated, DCL is held in a low state.
See section 1.5.1, 1.5.2 and 1.5.3.
3
DD
BI
The IOM-2 Data Downstream, receives data from the
network. When the bus is deactivated or when data is not
being transmitted, DD is high impedance. The IC Channel
Bus Reversal (TE mode only) allows IC1 and IC2 data to
be transmitted on the DD pin. See section 1.5.1, 1.5.2,
1.5.3 and 1.5.6. An external pull-up resistor is required.
4
DU
BI
The IOM-2 Data Upstream, transmits data to the network.
When the bus is deactivated or when data is not being
transmitted, DU is high impedance. The IC Channel Bus
Reversal (TE mode only) allows IC1 and IC2 data to be
received on the DU pin. See section 1.5.1, 1.5.2, 1.5.3
and 1.5.6. An external pull-up resistor is required.
5
TE/NTE
I/P
The IOM-2 two modes of operation: TE = 0 selects
Terminal mode. NTE = 1 selects Non-Terminal mode or
Line Card mode. See section 1.5.1, 1.5.2 and 1.5.3.
6
7
8
SA0
SA1
SA2
I/P
I/P
I/P
)
)
)
)
9
DS
I/P
The IOM-2 Device Select pin (NTE mode only). Allows two
CMX625 devices sharing a Slot Address to be individually
addressed. DS = 0 selects device one. DS = 1 selects
device two. See section 1.5.2 and 1.5.3.
10
RESET
I/P
The external reset pin clears all the registers. (RESET=1)
11
IRQN
O/P
A ‘wire-Orable’ output Interrupt Request. This output is
pulled down to VSS when active and is high impedance
when inactive. An external pull-up resistor is required.
Signal
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Description
The IOM-2 Slot Address, provides one of 8 unique
addresses. It allows the device to be individually
addressed when more than one device is connected
to the IOM-2 bus. See section 1.5.2 and 1.5.3.
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CMX625
CMX625
D5/P4
Signal
Description
Pin No.
Name
Type
12
VSS
Power
13
RXP
I/P
The non-inverting input of the receive op-amp.
14
RXN
I/P
The inverting input of the receive op-amp.
15
RXO
O/P
The output of the receive op-amp.
16
VBIAS
O/P
An internally generated bias voltage of VDD/2, except
when the device has been reset, VBIAS will discharge to
VSS. It should be decoupled to VSS by a capacitor
mounted close to the device pins.
17
TONEFSK
O/P
The sinewave output of the Tones and FSK signal
generators.
18
TXO
O/P
The output of the buffer amplifier.
19
TXN
I/P
The inverting input to the buffer amplifier.
20
TXON
O/P
The inverted output of the buffer amplifier.
21
DAC OUT
O/P
The output from the digital-to-analogue converter.
22
RING
O/P
The square, trapezoidal and sinusoidal wave output from
the Ringing Signal Generator.
23
SPM
O/P
The sinewave output of the SPM signal generator.
24
VDD
Power
Notes:
I/P
O/P
BI
N/C
=
=
=
=
The negative supply rail (ground).
The positive supply rail. Levels and thresholds within the
device are proportional to this voltage. It should be
decoupled to VSS by a capacitor mounted close to the
device pins.
Input
Output
Bi-directional
No (external) Connection
This device is capable of detecting and decoding small amplitude signals. To achieve this VDD
and VBIAS decoupling and protecting the receive path from extraneous in-band signals are very
important. It is recommended that the printed circuit board is laid out with a ground plane in the
CMX625 area to provide a low impedance connection between the VSS pin and the VDD and VBIAS
decoupling capacitors.
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1.4
CMX625
External Components
VDD
FSC
VDD
DCL
R6
DD
R7
DU
IOM -2
Bus
Interface
TM
TE/NTE
SA0
SA1
SA2
DS
VDD
RESET
R1
IRQN
VSS
1
24
2
23
3
22
4
21
5
20
6
CMX625
19
7
18
8
17
9
16
10
15
11
14
13
12
VDD
C2
SPM
RING
VSS
DAC OUT
TXON
C6
TXN
TXO
R4
C5
Tx In
R5
TONEFSK
VBIAS
C1
RXO
R3
RXN
RXP
VBIAS
VSS
C4
R2
C3
Rx In
VSS
Figure 2 Recommended External Components
R1, R4
R2, R3
R5
R6, R7
100kΩ
110kΩ
56kΩ
Note 2
C1, C2
C3
C4, C5
C6
1.0µF
100nF
220pF
22nF
Resistor ±1%, capacitors ±5% unless otherwise stated.
Note:
1. The recommended component values, C3 to C6 and R2 to R5 and tolerances are essential to
meet the ITU-T Recommendation G.172 filter specification. See figure 12.
2. R6, R7 = 750Ω with 5V supply. R6, R7 = 470Ω with 3.3V supply.
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1.5
CMX625
General Description
The CMX625 is a telecom tone generator, DTMF tone encoder/decoder and PCM Codec-Filter for ISDN
interfaces. The PCM Codec-Filter performs voice digitisation and reconstruction and incorporates encoder
bandpass and decoder lowpass filters with pre and post-filtering with selectable A-law and µ-law
companding following ITU-T recommendation G.711. The device has separate output ports for the four
different classes of signals encoded. These include Ringing signals, In-band tones or FSK data at
1200bps, high frequency metering pulses (SPM tones) and DAC signals. It has a transmit level attenuator
for In-band tones or FSK data and an envelope control for SPM tones. The device also has an
uncommitted Tx output buffer for filtering and impedance matching. The functions are controlled via an
IOM-2 serial bus interface.
Frequency and timing accuracy of the CMX625 is supplied by the Data Clock (DCL) of the IOM-2 serial
bus interface. If the bus is deactivated, DCL is held in a low state.
The CMX625 can be reset externally by driving the RESET pin low. It resets all the internal register bits
and ensures that the interface always starts from a known state. The device can also be reset by issuing
a RESET command. See section 1.5.14. Commands to enable and disable individual functions are also
shown in this section. Approximately 50ms should be allowed for the Tx dc level to settle at VBIAS before
enabling the Tx functions (set bit 6 of the MODE Register to ‘1’) after the CMX625 has been reset.
1.5.1
IOM-2 Serial Bus Interface
®
The IOM -2 (ISDN Oriented Modular revision 2) is an industry standard serial bus for interconnecting
telecommunications IC’s. (Refer to the IOM-2 Interface Reference Guide, Industry Standard Bus by
®
Advanced Micro Devices). The bus is an evolution of the IOM interface and is also known as the GCI
(General Circuit Interface).
The IOM-2 bus provides a symmetrical full duplex communication link, containing user data,
control/programming and status channels. There are two basic modes of operation known as Terminal
mode (TE mode) and non-Terminal mode (non-TE or Line Card mode). These modes differ in the frame
structure and data rate. The frame rate remains at 8kHz for each mode. The CMX625 acts as a timing
and control slave to the upstream device.
The various channels are time multiplexed over a basic four wire serial interface, namely FSC, DCL, DD
and DU. Frames are delimited by an 8kHz Frame Synchronisation Clock (FSC) which is generated by the
upstream device. The Data Clock (DCL) clocks data on and off the bus and runs at either 1.536MHz (TE
mode) or 4.096MHz (non-TE mode). It is always generated by the upstream device. Data Downstream
(DD) receives data from the network. Data Upstream (DU) transmits data to the network. When the bus
is deactivated or when data is not being transmitted, DD and DU is held in a high impedance state. The
DD and DU bus are driven by open drain transistors such that all DD’s and DU’s can be connected
together. Bus reversal (in TE mode) allows the DD and DU pins to be both inputs and outputs in the IC1
and IC2 channels. It allows use of the CMX625 with post processing devices that are IOM-2 compliant.
When other devices are connected to the IOM-2 bus the three Slot Address pins (SA0, SA1 and SA2)
provide a unique address, allowing the CMX625 to be individually addressed. The Device Select pin (DS)
allows two CMX625 devices sharing a slot address to be individually addressed in non-TE mode.
The remote digital IOM loopback is enabled when bit 3 of the IOM CONTROL Register is set to ‘1’. This
loops back the data arriving on the IOM-2 bus and sends it back again. Unused bits in the frame structure
are ignored if not required by the CMX625. These bits will be set to '1' when the frame is transmitted
upstream.
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1.5.2
CMX625
Terminal Mode (TE)
Terminal mode (TE) frame structure consists of 3 channels of 4 bytes each repeated at 8kHz, i.e. 96 bits
in 125µs or a data rate of 768kbps. The Data Clock (DCL) operates at twice the data rate, i.e. 1.536MHz.
Figure 3 shows the TE mode frame structure.
125µs
FSC
DCL
DU/DD
CHANNEL 0
CHANNEL 1
CHANNEL 0
B1
B2
CHANNEL 1
IC1
IC2
CHANNEL 2
Not Used
Not Used
CHANNEL 2
MON0
M
S
B
MON1
D
L
S
B
Not Used
MM
C/I0 R X
C/I1
MM
RX
TIC
FSC
= 8kHz
DCL
= 1.536MHz
DD, DU = 768kbps
Figure 3 Terminal Mode Frame Structure
‘Channel 0’ is used for passing user data (2B+D channels) and controlling (MON0 and C/I0) the Layer 1
transceiver. Only ‘Channel 1’ is used by the CMX625. ‘Channel 2’ is reserved for D channel arbitration.
The 12 byte frame contains the following channels:
(i)
The ‘B’ channels consist of two 64kbps data channels, labelled B1 and B2, and transfer B channel
data to and from the network.
(ii) The ‘Monitor’ channels consist of two programming channels, labelled MON0 and MON1. Each
channel consists of 8 bits of data and has two associated pair of handshake bits that control data
flow, MX and MR (monitor transmit and receive). The handshake procedure is described in section
1.5.4. The MON1 channel is used for programming and controlling devices attached to the IOM-2
interface. The CMX625 is programmed via the MON1 channel (see section 1.5.15). The MON0
channel is not used. Monitor channel contention is avoided by a “speak when spoken to” system
whereby the CMX625 is given a unique address, programmed with the 3 Slot Address pins (SA0 to
SA2) and 1 Device Select pin (DS) and only responds when that address is broadcast by the master
device (see section 1.5.14). The Monitor channel address byte is shown below:
Bit 7
MON Channel
Address
Byte
1
 2001 Consumer Microcircuits Limited
Bit 6
Slot
Address
SA2
Bit 5
Slot
Address
SA1
8
Bit 4
Slot
Address
SA0
Bit 3
Device
Select
DS
Bit 2
Bit 1
Bit 0
0
0
0
D/625/2
ISDN TA POTS Interface
CMX625
The CMX625 cannot initiate MON communication directly in a multi-slave application. Each slave
must monitor the MON channel for its unique address in the first byte before processing the following
command. Each slave can therefore only drive the DU MON channel when specifically requested to
by the master.
(iii) The ‘D’ channel consists of two bits providing 16kbps for carrying D channel user data. This channel
is not used by the CMX625.
(iv) The ‘Command/Indicate’ channels, labelled C/I0 and C/I1, provide real time status information
between devices connected via the IOM-2 bus. The C/I0 in channel 0 consists of 4 bits and the C/I1
in channel 1 is 6 bits wide. The C/I0 in channel 0 is not used.
The C/I1 channel is shared by all devices on the IOM-2 bus with no mechanism for determining and
resolving contention. If multiple slave devices are expected to drive the C/I1 channel then care must
be taken to allocate different bits to each device. An example of C/I1 channel usage would be 6 slave
devices each allocated one of the 6 C/I1 bits. When a slave requires attention it asserts its own bit,
which is detected by the master as a C/I1 value change (generating a processor interrupt). The
processor would then initiate MON1 communications with the appropriate slave and service its
request. This is an example of one usage, but the C/I1 bits may be used for any real time
command/indicate purpose dependent on system design and number of slaves on the IOM-2 bus.
The C/I1 Channel Output Control Code is encoded as follows (bits 0, 1 and 2 of the IOM CONTROL
Register):
C/I1 Channel Output Control
Code (IOM Control Register,
Bits 2, 1 and 0)
000
001
010
011
100
101
110
111
C/I1 Channel Output Bit Content
C/I1 bits 5-0 = all logic ‘1’, i.e. C/I1 output disabled
Interrupt Request (logic ‘0’) on C/I1 bit 0 )
Interrupt Request (logic ‘0’) on C/I1 bit 1 )
Interrupt Request (logic ‘0’) on C/I1 bit 2 ) all other bits logic ‘1’
Interrupt Request (logic ‘0’) on C/I1 bit 3 )
Interrupt Request (logic ‘0’) on C/I1 bit 4 )
Interrupt Request (logic ‘0’) on C/I1 bit 5 )
Status Register bits 7-2 on C/I1 bits 5-0
Code ‘000’ is provided to disable drive of the C/I1 channel for use when multiple slaves have
completely utilised the C/I1 channel resource. The Interrupt Mask Register settings are ignored and
the C/I1 bits are set to logic ‘1’.
For codes ‘001’ to ‘110’ a logic ‘0’ (Interrupt Request) is driven onto the appropriate C/I1 bit when the
Status Register bits contain an unmasked logic ‘1’ (set by the Interrupt Mask Register). This allows
other devices to use the remaining C/I bits for their own purposes. The master device would use the
change of the appropriate C/I bit to initiate a Status Register read from the CMX625.
Code ‘111’ and an unmasked Status Register (INTERRUPT MASK bits 2 to 7 are set to ‘1’) allows the
most significant 6 bits of the Status Register to be driven onto the C/I1 channel directly for use when
the CMX625 is the only slave utilising the C/I channel. If any of the Status bits are masked, by setting
the equivalent bit in the mask register to ‘0’, then a logic ’0’ will be routed to the appropriate C/I1 bit
and will not change.
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CMX625
(v) The ‘Intercommunication Channel’ consists of two 64kbps data channels, labelled IC1 and IC2, and
provide additional communications paths between devices other than the layer 1 device (data to and
from the layer 1 device is transferred over the B channels).
(vi) The ‘TIC’ (Terminal IC) bus is used for connecting more than one device to the D and C/I0 channels
in Channel 0. The TIC bus is not used by the CMX625.
1.5.3
Non-Terminal Mode (non-TE)
The non-TE mode (Line Card Mode) frame structure consists of up to 8 channels of 4 bytes each repeated
at 8kHz, i.e. 256 bits in 125µs or a data rate of 2048kbps for 8 channel frames. The Data Clock (DCL)
operates at twice the data rate, i.e. 4.096MHz. Figure 4 shows the non-TE mode frame structure.
125µs
FSC
DCL
DD
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
CH0
DU
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
CH0
B2
M
S
B
MONITOR S
M
S
B
MONITOR S
B1
B1
B2
L
C/I
B
L
B
D
C/I
MM
R X for analogue lines
MM
R X for ISDN lines
FSC
= 8kHz
DCL
= 4.096MHz
DD, DU = 2048kbps
Figure 4 Non-Terminal Mode Frame Structure
In non-TE mode the IOM-2 bus time multiplexes data, control and status information for up to eight IOM-2
devices or up to 16 Codec-Filters over a single full duplex interface. The frames are subdivided into 8
channels, with one channel being dedicated to each IOM-2 device or pair of Codecs.
Each device on the IOM-2 bus is assigned a slot address and only transmits to and receives from that time
slot. Pins SA0, SA1 and SA2 on the CMX625 are used to program the Slot Address. Outside the
allocated slot the transmit drivers will be set to high impedance to allow other devices to transmit in their
own time slot. To allow two CMX625 devices to share the same slot a Device Select pin (DS) is made
available. This pin forms part of the Monitor Channel Address Byte along with the Slot Address pins and
allows either of the two devices sharing a slot to be individually addressed. See section 1.5.2, part (ii)
MON Channel Address Byte. This mechanism allows both the B1 and B2 data from the same time slot to
be utilised by different devices.
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CMX625
Each channel consists of the following 4 bytes:
(i)
The first two bytes consist of two 64kbps data channels, labelled ‘B1’ and ‘B2’, and transfer B channel
data to and from the network.
(ii)
The third byte, labelled ‘Monitor’, is used for programming and controlling devices attached to the
IOM-2 interface. The data structure within the monitor channel is not defined and will be device
specific. The CMX625 is programmed via the monitor channel (see section 1.5.15).
(iii) In digital applications (ISDN line cards) the fourth byte contains two bits for the 16kbps ‘D’ channel,
four ‘Command/Indicate’ (C/I) bits for real time status information and two handshake bits for
supporting the handling of the monitor channel, labelled ‘MR’ and ‘MX’ (monitor transmit and receive).
The handshake procedure is described in section 1.5.4. In analogue applications (analogue line
cards) there is no 'D' channel in the fourth byte so the adjacent C/I channel is increased to 6 bits. The
C/I1 channel bits are used in the same way as for Terminal Mode.
1.5.4
Monitor Channel Handshake Protocol
The Monitor channel operates on an event driven basis. While data transfers on the bus take place
synchronised to the frame sync, the flow of data is controlled by a handshake procedure using the
outgoing MX (monitor transmit) and incoming MR (monitor receive) bits. Data is placed onto the monitor
channel and the MX bit is activated. This data will be transmitted repeatedly (once per 8kHz frame) until
the transfer is acknowledged (ACK) via the MR bit. The actual data rate is not fixed but is dependent upon
the response speed of the transmitter and receiver. The protocol is applicable to both TE and non-TE
modes.
EOM
MX
Data
Byte 1
Byte 2
Byte 3
Byte n
MR
ACK
ACK
ACK
ACK
125µs
Figure 5 Monitor Handshake Timing (general case)
Figure 5 shows the general case for monitor handshake timing. The first byte of data is placed on the bus
and MX is activated (low). MX remains active and the data remains valid until an inactive-to-active
transition of MR is received, indicating that the receiver has read the data off the bus. The next byte is
placed on the bus after the inactive-to-active transmission of MR, as early as the next frame (there is no
limit to the maximum number of frames). At the time that the second byte is transmitted, MX is returned
inactive (high) for one frame (MX inactive for more than one frame indicates an End of Message). In
response to MX going active (low), MR will be deactivated (high) for one frame (the MX inactive to MR
inactive delay can be any number of frames). This procedure is repeated for each additional byte. The
transmitter sends an End of Message (EOM), after the last byte of data has been transmitted, by not
reactivating MX after deactivating it.
The receiver can hold off the transmitter by keeping MR active until the receiver is ready for the next byte.
The transmitter will not start the next transmission cycle until MR goes inactive.
The transmitter is able to abort a transmission by holding MX inactive (high) for two or more frames, this
will generate an interrupt when the INTERRUPT MASK Register bit 3 is unmasked (logic ‘1’) and bit 3 of
the Status Register will be set to ‘1’.
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CMX625
Figure 6 shows the monitor channel handshake procedure.
MX = Monitor Transmit Bit, active low.
MR = Monitor Receive Bit, active high.
MD = Monitor Data
Figure 6 Monitor Channel Handshake Procedure
Figure 7 shows the maximum speed case for monitor handshake timing. The transmitter can be designed
for a higher data throughput than is provided by the general case. The transmitter can deactivate (high)
MX and transmit new data one frame after MR is deactivated. In this way, the transmitter is anticipating
that MR will be reactivated one frame after it is deactivated, minimising the delay between bytes. MR
being held inactive (high) for two or more frames indicates an abort is being signalled by the receiver.
EOM
MX
Data
Byte 1
Byte 2
Byte 3
Byte n
MR
ACK
ACK
ACK
ACK
Figure 7 Monitor Handshake Timing (maximum speed case)
The abort is a signal from the receiver to the transmitter indicating that data has been missed. The
receiver is able to abort a transmission by holding MR inactive (high) for two or more frames in response
to MX going active. An abort from the receiver will generate an interrupt when the INTERRUPT MASK
Register bit 2 is unmasked (logic ‘1’) and bit 2 of the Status Register will be set to ‘1’. Figure 8 shows a
monitor abort request from the receiver.
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CMX625
EOM
MX
Data
Byte 1
Byte 2
Abort Request
MR
Figure 8 Abort Request from the Receiver
1.5.5
Monitor Channel Identification Command
In order to be able to identify different devices on the IOM-2 bus, an identification command is sent. This
allows the software to identify different manufacturer's devices on the bus. The identification sequence is
usually done once, when the device is connected for the first time.
A device requesting the identity of a connected CMX625 will transmit the following 2 byte command:
st
DD 1 byte
nd
DD 2 byte
Bit7
1
0
Bit6
SA2
0
Bit5
SA1
0
Bit4
SA0
0
Bit3
DS
0
Bit2
0
0
Bit1
0
0
Bit 0
0
0
Bit3
DS
1
Bit2
0
0
Bit1
0
0
Bit 0
0
1
The CMX625 responds by transmitting:
st
DU 1 byte
nd
DU 2 byte
Bit7
1
1
Bit6
SA2
0
Bit5
SA1
0
Bit4
SA0
1
Monitor Channel Address Byte
Device Identification Byte
SA(2-0) = Slot Address, DS = Device Select (see sections 1.5.2 and 1.5.3). See section 1.5.14 for the
Device Identification Register.
1.5.6
PCM Codec-Filter
The PCM Codec-Filter performs voice digitisation and reconstruction and incorporates encoder bandpass
and decoder lowpass filters with pre and post-filtering with selectable A-law and µ-law companding. In
each case the coder and decoder process a companded 8-bit PCM word following ITU-T recommendation
G.711 for A-law and µ-law conversion. The encoder bandpass filter and decoder lowpass filter provide
passband flatness and stopband rejection according to ITU-T recommendation G.712. The lowpass filter
contains the required (Sin X)/X compensation. The overall filter characteristics of the channel are shown
in Figure 12.
The PCM Codec-Filter block is enabled or disabled by bit 7 of the CODEC CONTROL Register. The
companding law is selected by bit 6. When this bit is a ‘0’, A-law companding is selected (used in Europe)
and when this bit is a ‘1’, µ-law is selected (used in the USA and Japan).
The PCM Codec Channel routeing is shown in the table below for normal operation and bus reversal. In
‘normal’ operation, bit 4 of the IOM Control Register is set to ‘0’, the data is transmitted on the Data
Upstream (DU) pin and received on the Data Downstream (DD) pin. Bits 6 and 7 of the IOM Control
Register select whether the data is transmitted or received on the B1, B2, IC1 or IC2 channels of the IOM2 bus. The B1 and B2 channels are available in TE and non-TE mode but the IC1 and IC2 channels are
only available in TE mode.
 2001 Consumer Microcircuits Limited
13
D/625/2
ISDN TA POTS Interface
CMX625
Codec Channel Input/Output Select
IC Channel Bus Reversal
Codec Channel Select
Codec
(IOM Control Register
(IOM Control Register,
Data
Bit 4)
Bits 7 and 6)
From
0
00
B1, DD
Normal
0
01
B2, DD
0
10
IC1, DD
0
11
IC2, DD
1
00
B1, DD
Reverse
1
01
B2, DD
1
10
IC1, DU
1
11
IC2, DU
Codec
Data
To
B1, DU
B2, DU
IC1, DU
IC2, DU
B1, DU
B2, DU
IC1, DD
IC2, DD
In Terminal mode (TE) it may also be necessary to transmit on the Data Downstream (DD) pin and receive
on the Data Upstream (DU) pin during the IC1 and IC2 time slots. This can be achieved by selecting bus
reversal and allows use of the CMX625 with post processing devices, such as speech scramblers, that are
IOM-2 compliant. Bus Reversal is enabled when bit 4 of the IOM Control Register is set to ‘1’ and
programming the appropriate Codec Channel Select bits 6 and 7 of the IOM Control Register. When bus
reversal is active, the master device and any other devices capable of bus reversal, are prohibited from
broadcasting in the active IC channel.
Local analogue codec loopback is enabled when bit 5 of the CODEC CONTROL Register is set to ‘1’.
This internally connects the DAC output to the ADC input (the connection to the Rx Amp is broken). Data
is loaded and read via the IOM-2 bus using the channels shown in the above table.
1.5.7
Rx Input Amplifier
This amplifier, with suitable external components, is used for adjusting the received signal to the correct
amplitude for the DTMF decoder and the PCM analogue-to-digital converter. See Figure 2 Recommended
External Components.
1.5.8
Tx Output Buffer
This buffer is enabled by bit 7 of the SETUP register. With suitable external components it can be used
for filtering and impedance matching. See Figure 2 Recommended External Components.
1.5.9
Tone/FSK Encoder and Tone Encoder
These blocks are enabled or disabled by bit 6 of the SETUP register. When bit 5 of the MODE Register is
set to ‘1’ then these blocks generate FSK signals as determined by bit 0 of the SETUP Register and the Tx
data bits from the UART block, as shown in the table below:
SETUP Register
Bit 0
0
1
Tone/FSK Generator
V23 1200bps FSK
Bell 202 1200bps FSK
FSK Signal Frequency
‘0’ (Space)
2100Hz
2200Hz
FSK Signal Frequency
‘1’ (Mark)
1300Hz
1200Hz
When bit 5 of the MODE Register is set to ‘0’, these blocks generate single or dual tones from the range
shown in the tables on the following pages. Bit 6 of the MODE Register is then used to enable or disable
the block’s output to the Tx Signal Control, RING and TONEFSK outputs. There are four tone fields
addressed by bits 0 and 1 of the MODE Register.
 2001 Consumer Microcircuits Limited
14
D/625/2
ISDN TA POTS Interface
CMX625
Tone Field 0, MODE Register bit 1 and bit 0 = ‘0’ and ‘0’ respectively.
TX TONES Register Bits
D7
D6
D5
0
0
0
0
0
0
0
0
1
0
0
1
0
1
0
0
1
0
0
1
1
0
1
1
1
0
0
1
0
0
1
0
1
1
0
1
1
1
0
1
1
0
1
1
1
1
1
1
4-7
D4
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Frequency
(Hz)
0 = OFF
252.4
268.7
285.3
315.5
330.5
375.2
404.3
468.0
495.8
520.6
548.0
562.8
578.4
595.0
612.5
TX TONES Register Bits
D3
D2
D1
0
0
0
0
0
0
0
0
1
0
0
1
0
1
0
0
1
0
0
1
1
0
1
1
1
0
0
1
0
0
1
0
1
1
0
1
1
1
0
1
1
0
1
1
1
1
1
1
0-3
D0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Frequency
(Hz)
0 = OFF
* 17.1
* 20.5
* 24.9
* 34.1
* 41.0
* 51.2
262.9
293.6
348.2
392.6
1600
1633
1827
587.2
NOTE: * These outputs are routed to the RING digital output instead of the TONEFSK output. Any single
tone output level at TONEFSK output is 0dBm.
Tone Field 1, MODE Register bit 1 and bit 0 = ‘0’ and ‘1’ respectively
TX TONES Register Bits 4-7
D7
D6
D5
D4
0
0
0
0
0
0
0
1
0
0
1
0
0
0
1
1
0
1
0
0
0
1
0
1
0
1
1
0
0
1
1
1
1
0
0
0
1
0
0
1
1
0
1
0
1
0
1
1
1
1
0
0
1
1
0
1
1
1
1
0
1
1
1
1
 2001 Consumer Microcircuits Limited
Frequency
(Hz)
0 = OFF
120
150
154
250
300
350
360
367
375
380
383
400
450
475
480
TX TONES Register Bits 0-3
D3
D2
D1
D0
0
0
0
0
0
0
0
1
0
0
1
0
0
0
1
1
0
1
0
0
0
1
0
1
0
1
1
0
0
1
1
1
1
0
0
0
1
0
0
1
1
0
1
0
1
0
1
1
1
1
0
0
1
1
0
1
1
1
1
0
1
1
1
1
15
Frequency
(Hz)
0 = OFF
330
416
420
425
433
440
450
460
480
500
600
620
720
930
-
D/625/2
ISDN TA POTS Interface
CMX625
Tone Field 2, MODE Register bit 1 and bit 0 = ‘1’ and ‘0’ respectively
TX TONES Register Bits
D7
D6
D5
0
0
0
0
0
0
0
0
1
0
0
1
0
1
0
0
1
0
0
1
1
0
1
1
1
0
0
1
0
0
1
0
1
1
0
1
1
1
0
1
1
0
1
1
1
1
1
1
4-7
D4
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Frequency
(Hz)
0 = OFF
700
900
1100
1300
1500
1700
950
1400
1800
2130
697
770
852
941
TX TONES Register Bits
D3
D2
D1
0
0
0
0
0
0
0
0
1
0
0
1
0
1
0
0
1
0
0
1
1
0
1
1
1
0
0
1
0
0
1
0
1
1
0
1
1
1
0
1
1
0
1
1
1
1
1
1
0-3
D0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Frequency
(Hz)
0 = OFF
700
900
1100
1300
1500
1700
2100
2225
2750
1209
1336
1477
1633
0-3
D0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Frequency
(Hz)
0 = OFF
540
660
780
900
1020
1140
1380
1500
1620
1740
1860
1980
-
Tone Field 3, MODE Register bit 1 and bit 0 = ‘1’ and ‘1’ respectively
TX TONES Register Bits
D7
D6
D5
0
0
0
0
0
0
0
0
1
0
0
1
0
1
0
0
1
0
0
1
1
0
1
1
1
0
0
1
0
0
1
0
1
1
0
1
1
1
0
1
1
0
1
1
1
1
1
1
4-7
D4
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
 2001 Consumer Microcircuits Limited
Frequency
(Hz)
0 = OFF
540
660
780
900
1020
1140
1380
1500
1620
1740
1860
1980
-
TX TONES Register Bits
D3
D2
D1
0
0
0
0
0
0
0
0
1
0
0
1
0
1
0
0
1
0
0
1
1
0
1
1
1
0
0
1
0
0
1
0
1
1
0
1
1
1
0
1
1
0
1
1
1
1
1
1
16
D/625/2
ISDN TA POTS Interface
CMX625
1.5.10 SPM Generator
This block operates independently and has its own output pin. It can transmit 12kHz or 16kHz and is
controlled by bit 4 of the SETUP Register. Bit 7 of the MODE Register is used to enable or disable this
block. The signal has a rise and fall time each of about 4ms. The SPM signal rises from the bias level to
0dBm in 16 steps of ≈2dB magnitude, and falls from 0dBm to bias level in 16 steps of ≈2dB magnitude.
1.5.11 Transmit Signal Control
This block adjusts the amplitude of the FSK transmit signal output level, the level skew between DTMF
tones and the signal routing to the output ports.
Output signal levels are proportional to VDD. The nominal output signal levels (at 0dB attenuation and VDD
= 5.0V) are:
Single Tone
Dual Tone (per tone)
DTMF High Frequency Tone
DTMF Low Frequency Tone
FSK Signal
0dBm
-3dBm
-3dBm
-5dBm
0dBm
The level attenuator provides for level adjustment from 0dB to -14dB in -2dB steps. The typical level is
determined by bits 2 to 4 of the MODE Register as shown in the table below:
MODE Register
Bit 4
Bit 3
Bit 2
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
Signal Level Adjustment
(dB)
0
-2
-4
-6
-8
-10
-12
-14
The RING signal is a square, trapezoidal or sinusoidal wave. The square and trapezoidal wave have an
amplitude of ≈ VDD peak to peak and the sinusoidal wave has an amplitude of ≈ ½ VDD peak to peak. The
trapezoidal ringing waveform has a crest factor (CF) of 1.35. Bits 2 and 3 of the SETUP Register select
the waveform type as shown in the table below.
SETUP Register
Bit 3
Bit 2
0
0
0
1
1
0
 2001 Consumer Microcircuits Limited
RING Signal Select
Square wave
Trapezoidal wave
Sinusoidal wave
17
D/625/2
ISDN TA POTS Interface
CMX625
1.5.12 Tx UART
This block connects the IOM-2 serial bus interface to the FSK Encoder.
The block can be programmed to convert transmit data from 8-bit bytes to asynchronous data characters
by adding Start and Stop bits. The transmit data is then passed to the FSK Encoder.
Data to be transmitted should be loaded, via the IOM-2 bus interface, into the TX DATA Register when the
Tx Data Ready bit (bit 6) of the STATUS Register goes high. It will then be treated by the Tx UART block
in one of two ways, depending on the setting of bit 1 of the SETUP Register:
If bit 1 of the SETUP Register is ‘0’ (Tx Sync mode) then the 8 bits from the TX DATA Register will
be transmitted sequentially at 1200bps, lsb (D0) first.
If bit 1 of the SETUP Register is ‘1’ (Tx Async mode) then bits will be transmitted as asynchronous
data characters at 1200 bps according to the following format:
One Start bit (Space)
Eight Data bits (D0-D7) from the TX DATA Register, with the lsb (D0) transmitted first
One Stop bit (Mark)
Failure to load the TX DATA Register with a new value when required will result in bit 7 (Tx Data
Underflow) of the STATUS Register being set to ‘1’. If the ‘Tx Async’ mode of operation is selected then a
continuous Mark (‘1’) signal will be transmitted until a new value is loaded into TX DATA. If the ‘Tx Sync’
mode is selected then the byte already in the TX DATA Register will be re-transmitted.
Figure 9a Transmit UART Function (Async)
Figure 9b Transmit UART Function (Sync)
 2001 Consumer Microcircuits Limited
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D/625/2
ISDN TA POTS Interface
CMX625
1.5.13 DTMF Tone Decoder
This block is enabled or disabled by bit 5 of the SETUP Register. If disabled, bit 4 and 5 of the STATUS
Register and bit 0 to bit 3 of the DTMF RX DATA Register are set to ‘0’ and no interrupts are generated.
When bit 5 of the SETUP Register is enabled and bit 4 of the INTERRUPT MASK Register is set to ‘1’ (i.e.
unmasked) a ‘detected tone’ generates an interrupt and bit 4 of the STATUS Register is set to ‘1’.
Reading the STATUS Register clears the IRQN output.
When bit 5 of the SETUP Register is enabled and bit 5 of the INTERRUPT MASK Register is unmasked
(logic ‘1’), a ‘status change’ of the decoder will generate an interrupt and bit 5 of the STATUS Register will
be set to ‘1’. The validity of the data is indicated by bit 4 of the STATUS Register. The decode truth table
is shown below. Reading the STATUS Register clears the IRQN output. An interrupt is not generated
when ‘no tone’ is detected.
DTMF RX DATA Register Bits 0 - 3
Bit 3
Bit 2
Bit 1
Bit 0
(D3)
(D2)
(D1)
(D0)
0
0
0
0
0
0
0
1
0
0
1
0
0
0
1
1
0
1
0
0
0
1
0
1
0
1
1
0
0
1
1
1
1
0
0
0
1
0
0
1
1
0
1
0
1
0
1
1
1
1
0
0
1
1
0
1
1
1
1
0
1
1
1
1
DTMF Tone Pairs
Lower Frequency
Upper Frequency
(Hz)
(Hz)
941
1633
697
1209
697
1336
697
1477
770
1209
770
1336
770
1477
852
1209
852
1336
852
1477
941
1336
941
1209
941
1477
697
1633
770
1633
852
1633
Keypad
Legend
D
1
2
3
4
5
6
7
8
9
0
*
#
A
B
C
A status change of the decoder and the generation of an interrupt (when the INTERRUPT MASK Register
bit 5 is unmasked) will occur both when a tone is first decoded and also when a tone, which was previously
present, is no longer decoded. In the latter case, bit 4 of the STATUS Register will be set to ‘0’ to indicate
that no tone was detected.
The decoded tone pair is indicated by bits 0-3 in the DTMF RX DATA Register.
 2001 Consumer Microcircuits Limited
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D/625/2
ISDN TA POTS Interface
CMX625
1.5.14 Register Set
Write Only Registers
Data Byte Structure
4
3
Addr.
Register
7
6
5
$1
RESET
N/A
N/A
N/A
N/A
DTMF Rx:
SPM:
SETUP
Tx Output
Buffer
0=Disable
1=Enable
SPM O/P:
0=Disable
1=Enable
Tx Enable
$3
0=Disable
1=Enable
Tone/FSK:
0=Disable
1=Enable
0=Disable
1=Enable
Tone/FSK:
0=Tone
1=FSK
0=12kHz
1=16kHz
Tx Level:
D7
MSB
D6
D5
D4
D7
MSB
D6
D5
$4
MODE
$5
TX
DATA
$6
TX
TONES
$8
IOM
CONTROL
Codec
Channel
Select [1]
Codec
Channel
Select [0]
INTERRUPT
MASK
Mask
Status [7]
Mask
Status [6]
$9
$C
CODEC
CONTROL
N/A
2
1
0
N/A
N/A
N/A
FSK Mode: FSK Mode:
Ring Signal Ring Signal
Select [1]
Select [0]
Tx Level:
MSB
D3
Tx Level:
LSB
MSB
LSB
D2
D1
D0
LSB
D1
D0
LSB
C/I1
Channel
Output
Control [1]
C/I1
Channel
Output
Control [0]
0
0
0
0
0
2
1
0
D4
D3
D2
LSB
MSB
IC Channel
Remote
Bus Reversal Digital IOM
C/I1
0
0=Normal
Loopback
Channel
1=Reverse 0=No loopbk
Output
1=Loopback Control [2]
Mask
Mask
Mask
Mask
Status [5]
Status [4]
Status [3]
Status [2]
Codec
Local
Enable
PCM Codec: Analogue
0=Disable
0=A-Law
Loopback
1=Enable
1=µ-Law 0=No loopbk
1=Loopback
0
0
0=Sync
0=V23
1=Async 1=Bell 202
Tone Fields: Tone Fields:
Read Only Registers
Addr.
$0
Register
DEVICE
ID
$A
STATUS
$B
DTMF RX
DATA
7
6
5
1
0
0
FSK Mode: FSK Mode: DTMF Rx:
FSK Tx Data FSK Tx Data
Status
Underflow
Ready
Change
0
0
0
Data Byte Structure
4
3
1
1
0
0
1
DTMF Rx:
1=Detected
0=No Tone
Time Out
IOM:
Tx
Abort
IOM:
Rx
Abort
0
0
DTMF:
Rx Data
(D3 MSB)
DTMF:
Rx Data
(D2)
DTMF:
Rx Data
(D1)
DTMF:
Rx Data
(D0 LSB)
0
Notes:
1. Accessing the RESET Register clears all of the bits in the SETUP, MODE, TX DATA, TX TONES,
IOM CONTROL, INTERRUPT MASK, CODEC CONTROL, STATUS and DTMF RX DATA registers
and will initialise the device. This a single-byte transaction consisting of the address byte value $1.
2. If any of bits 2, 3, 4, 5, 6 or 7 of the STATUS Register is ‘1’ then the IRQN output will be pulled low
when the appropriate bit contains an unmasked logic ‘1’ in the INTERRUPT MASK Register.
3. Reading the STATUS Register clears the IRQN output (when the appropriate bit contains an
unmasked logic ‘1’ in the INTERRUPT MASK Register) and also clears all the STATUS Register bits 2
to 7, if set.
1.5.15 Programming the CMX625
 2001 Consumer Microcircuits Limited
20
D/625/2
ISDN TA POTS Interface
CMX625
The CMX625 is programmed via the ‘MON1’ (Monitor Channel 1) channel in TE mode and the ‘Monitor’
channel in non-TE mode. The programming sequence consists of 3 consecutive Monitor bytes: the IOM-2
address, the CMX625 command and data byte. Before executing a command, the CMX625 compares the
received IOM-2 address byte with its own address. The MSB of the IOM-2 address is always a ‘1’ (see
section 1.5.2). A logical ‘1’ in the MSB of the CMX625 command represents a write operation and a
logical ‘0’ represents a read operation.
Structure for Register read/write operations:
IOM
Command
Register
R/W
0=Read
1=Write
0
X
X
Register
Address
A3
Register
Address
A2
Register
Address
A1
Register
Address
A0
Example 1: Program the CMX625 to generate interrupt requests for DTMF RX Status Change on bit 5 of
C/I channel, i.e. C/I1 Channel Output Control Code (2-0)=110. Set IOM-2 address to SA2-SA0=010 and
device select, DS=1.
MX
(DD)
MR
(DU)
DD
(hex)
MX
(DU)
MR
(DD)
DU
(hex)
1
0
0
1
0
1
0
1
1
0
0
1
0
1
0
1
1
1
1
1
0
0
1
0
1
0
1
1
0
0
1
0
1
0
1
1
FF
A8
A8
88
88
06
06
FF
FF
A8
A8
89
89
20
20
FF
FF
FF
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
Comment
Monitor Channel Idle State
Transmit IOM-2 Address
Acknowledge Address
Transmit Command (Write IOM-2 Control, $8)
Acknowledge Command/ Transmit IOM-2 Control Data
Acknowledge Data
End of Transmission
Transmit IOM-2 Address
Acknowledge Address
Transmit Command (Write Mask Register, $9)
Acknowledge Command/ Transmit IOM-2 Control Data
Acknowledge Data
End of Transmission
Idle
If the command is a register read then only the address and command bytes are sent. The CMX625 will
respond with an IOM-2 Register address byte followed by the read data. The IOM-2 Register address byte
consists of the Register address that is being read in the least significant 4 bits and the IOM-2 address
(less the device select bit) in the most significant 4 bits.
 2001 Consumer Microcircuits Limited
21
D/625/2
ISDN TA POTS Interface
CMX625
Example 2: Read the CMX625 DTMF RX DATA register, D3-D0=$A. Set IOM-2 address to SA2-SA0
=100 and device select, DS=0.
MX
(DD)
MR
(DU)
DD
(hex)
MX
(DU)
MR
(DD)
DU
(hex)
1
0
0
1
0
1
1
1
1
1
1
1
1
1
0
0
1
0
1
1
1
1
1
1
FF
C0
C0
0B
0B
FF
FF
FF
FF
FF
FF
FF
1
1
1
1
1
0
0
1
0
1
1
1
1
1
1
1
1
1
0
0
1
0
1
1
FF
FF
FF
FF
FF
CB
CB
0A
0A
FF
FF
FF
Comment
Monitor Channel Idle State
Transmit IOM-2 Address
Acknowledge Address
Transmit Command (Write IOM-2 Control, $B)
Acknowledge Command/ Send Address
Address Acknowledged
Send DTMF Read Data
Data Acknowledged
End of Transmission
Idle
1.5.16 Glossary
ADC
Analogue to Digital Converter
CIDCW
Caller Identification During Call Waiting
CODEC
Coder/Decoder
DAC
Digital to Analogue Converter
DTMF
Dual Tone Multiple Frequency
FSK
Frequency Shift Keying
GCI
General Circuit Interface
IOM-2
ISDN Oriented Modular revision 2
ISDN
Integrated Services Digital Network
ITU
International Telecommunication Union
NTU
Network Termination Unit
PC
Personal Computer
PCM
Pulse Code Modulation
POTS
Plain Old (Analogue) Telephone Service
SPM
Subscriber Pulse Metering
TA
Terminal Adaptor
 2001 Consumer Microcircuits Limited
22
D/625/2
ISDN TA POTS Interface
1.6
CMX625
Application Notes
When using the Tone/FSK bit (bit 6) of the MODE Register, each tone starts from VBIAS, and
returns to VBIAS before ending:
Figure 10 Tone Starting and Stopping
When switching between tones in the same column (bits 4 - 7 or bits 0 - 3) of the TX TONES
Register), the transition will be phase continuous. However, switching to the ‘OFF’ state will
immediately take the output of that tone generator to VBIAS.
Figure 11 Tone Changing
The TX TONES Register which does not have a frequency allocated is indicated by ‘-’ in the Tone
Field tables. These values should not be used.
1.6.1
Telecom Tones
The following tables give the hex codes to be programmed into the particular tone field location for
various telecommunications systems applications. The tables are not exhaustive, but list the more
commonly used tones.
Ringing Signals
(f ±2.5%)
(Hz)
Off
16.7
20
25
35
40
50
 2001 Consumer Microcircuits Limited
Field 0
(Hex)
$00
$01
$02
$03
$04
$05
$06
23
D/625/2
ISDN TA POTS Interface
CMX625
On Hook ‘CPE Alert Tones
Single Tone
(Hz)
375.2
404.3
468
495.8
520.6
548
562.8
578.4
1633
Field 0
(Hex)
$60
$70
$80
$90
$A0
$B0
$C0
$D0
$0D
Dual Tone
(Hz)
375.2+1827
404.3+1827
468+1827
495.8+1827
520.6+1827
548+1827
562.8+1827
578.4+1827
Field 0
(Hex)
$6E
$7E
$8E
$9E
$AE
$BE
$CE
$DE
Group B
(Hz)
468
495.8
520.6
562.8
595
612.5
Field 0
(Hex)
$80
$90
$A0
$C0
$E0
$F0
NYNEX (MRAA) - AMR Alert Tones (Single Tone)
Group A
(Hz)
252.4
268.7
285.3
315.5
330.5
375.2
Field 0
(Hex)
$10
$20
$30
$40
$50
$60
Single Frequency Call Progress Tones
(Hz)
Off
120
150
154
250
300
350
400
425
440
450
480
500
600
620
 2001 Consumer Microcircuits Limited
Field 1
(Hex)
$00
$10
$20
$30
$40
$50
$60
$C0
$04
$06
$07
$09
$0A
$0B
$0C
24
D/625/2
ISDN TA POTS Interface
CMX625
Dual Frequency Call Progress Tones
Additive Mixing
(Hz)
Off
350+440
440+480
480+620
400+425
400+450
425+450
425+480
120+620
150+450
Multiplicative
Field 1
(Hex)
$00
$66
$F6
$FC
$C4
$C7
$D4
$F4
$1C
$27
Mixing (Hz)
Field 1
(Hex)
400*16.2
400*20
400*25
400*33
400*40
400*50
450*25
600*120
$B2
$A3
$94
$85
$76
$67
$E4
$FD
Dual Tone Multi Frequency Generation
(Hz)
Off
941+1633
697+1209
697+1336
697+1477
770+1209
770+1336
770+1477
852+1209
852+1336
852+1477
941+1336
941+1209
941+1477
697+1633
770+1633
852+1633
Field 2
(Hex)
$00
$FF
$CC
$CD
$CE
$DC
$DD
$DE
$EC
$ED
$EE
$FD
$FC
$FE
$CF
$DF
$EF
Special Information Tones, Fax and Modem Tones and Customer Premises Alert Tones
(Hz)
Off
950
1100
1300
1400
1800
2100
2225
2130+2750
 2001 Consumer Microcircuits Limited
Field 2
(Hex)
$00
$80
$30
$40
$90
$A0
$08
$09
$BB
25
D/625/2
ISDN TA POTS Interface
CMX625
ITU-T ‘R1’ Signalling Tones
(Hz)
700+900
700+1100
900+1100
700+1300
900+1300
1100+1300
700+1500
900+1500
1100+1500
1300+1500
700+1700
900+1700
1100+1700
1300+1700
1500+1700
Field 2
(Hex)
$12
$13
$23
$14
$24
$34
$15
$25
$35
$45
$16
$26
$36
$46
$56
ITU-T ‘R2’ Signalling Tones
Forward mode
(Hz)
Off
1380+1500
1380+1620
1500+1620
1380+1740
1500+1740
1620+1740
1380+1860
1500+1860
1620+1860
1740+1860
1380+1980
1500+1980
1620+1980
1740+1980
1860+1980
 2001 Consumer Microcircuits Limited
Field 3
(Hex)
$00
$89
$8A
$9A
$8B
$9B
$AB
$8C
$9C
$AC
$BC
$8D
$9D
$AD
$BD
$CD
Backward mode
(Hz)
Off
1140+1020
1140+900
1020+900
1140+780
1020+780
900+780
1140+660
1020+660
900+660
780+660
1140+540
1020+540
900+540
780+540
660+540
26
Field 3
(Hex)
$00
$65
$64
$54
$63
$53
$43
$62
$52
$42
$32
$61
$51
$41
$31
$21
D/625/2
ISDN TA POTS Interface
1.7
Performance Specification
1.7.1
Electrical Performance
CMX625
1.7.1.1 Absolute Maximum Ratings
Exceeding these maximum ratings can result in damage to the device.
Min.
-0.3
-0.3
-50
-20
Max.
7.0
VDD + 0.3
+50
+20
Unit
V
V
mA
mA
D5 Package
Total Allowable Power Dissipation at Tamb = 25°C
... Derating
Storage Temperature
Operating Temperature
Min.
-55
-40
Max.
550
9
+125
+85
Unit
mW
mW/°C
°C
°C
P4 Package
Total Allowable Power Dissipation at Tamb = 25°C
... Derating
Storage Temperature
Operating Temperature
Min.
-55
-40
Max.
800
13
+125
+85
Unit
mW
mW/°C
°C
°C
Min.
2.7
-40
Max.
5.5
+85
Unit
V
°C
Supply (VDD - VSS)
Voltage on any pin to VSS
Current into or out of VDD and VSS pins
Current into or out of any other pin
1.7.1.2 Operating Limits
Correct operation of the device outside these limits is not implied.
Notes
Supply (VDD - VSS)
Operating Temperature
 2001 Consumer Microcircuits Limited
27
D/625/2
ISDN TA POTS Interface
CMX625
1.7.1.3 Operating Characteristics
For the following conditions unless otherwise specified:
VDD = 2.7V at Tamb = 25°C and VDD = 3.0V to 5.5V at Tamb = -40 to +85°C,
0dBm = 775mVrms = 0dBm0.
DC Parameters
IDD All Enabled, VDD = 5.0V
All Disabled, VDD = 5.0V
DTMF Rx only, VDD = 5.0V
Tx (tones, SPM) only, VDD = 5.0V
Tx Output Buffer only Enabled, VDD = 5.0V
PCM Codec only, VDD = 5.0V
All Enabled, VDD = 3.3V
All Disabled, VDD = 3.3V
DTMF Rx only, VDD = 3.3V
Tx (tones, SPM) only, VDD = 3.3V
Tx Output Buffer only Enabled, VDD = 3.3V
PCM Codec only, VDD = 3.3V
Notes
1
1
1
1
1
1
1
1
1
1
1
1
Min.
-
Typ.
6.9
140
2.4
3.5
1.8
3.1
5.0
80
1.6
2.3
1.3
2.3
Max.
-
Unit
mA
µA
mA
mA
mA
mA
mA
µA
mA
mA
mA
mA
Logic ‘1’ Input Level (CMOS inputs)
Logic ‘0’ Input Level (CMOS inputs)
Logic Input Leakage Current (Vin = 0 to VDD)
Logic ‘1’ Input Level (TTL inputs)
Logic ‘0’ Input Level (TTL inputs), Vdd = 3.3V-5.5V
Output Logic ‘1’ Level DD, DU (IOH = 4mA)
Output Logic ‘0’ Level DD DU (IOL = 6mA)
Output Logic ‘0’ Level IRQN (IOL = 3mA)
IRQN O/P ‘Off State Current (VOUT = VDD)
3
3
3
3
3, 13
14
14
14
70%
-1.0
2.0
0.8
-
-
30%
+1.0
0.8
0.4
0.4
1.0
V
V
µA
V
V
VDD
V
V
µA
FSK Encoder and Tx UART
Notes
Min.
Typ.
Max.
Unit
4
-1.0
-2.0
0
0
1.0
+2.0
dBm
dB
1194
1297
2097
1200
1300
2100
1206
1303
2103
Baud
Hz
Hz
1194
1197
2197
1200
1200
2200
1206
1203
2203
Baud
Hz
Hz
Notes
Min.
Typ.
Max.
Unit
4
4
4
4
-1.0
-4.0
-4.0
-6.0
-2.5
-
0
-3.0
-3.0
-5.0
10.0
0.8
1.0
-2.0
-2.0
-4.0
2.5
-
dBm
dBm
dBm
dBm
kΩ
Hz
%
Level at TONEFSK pin
Twist (Mark level w.r.t. Space level)
Tx 1200bits/sec (V23 mode)
Baud Rate (set by UART and DCL)
Mark (Logical 1) Frequency
Space (Logical 0) Frequency
Tx 1200bits/sec (Bell 202 mode)
Baud Rate (set by UART and DCL)
Mark (Logical 1) Frequency
Space (Logical 0) Frequency
TONEFSK Signal Level
Level at TONEFSK pin for:
Single tone
Dual tone (per tone)
DTMF High Frequency Group
DTMF Low Frequency Group
Output Impedance
Tone frequency resolution
Tone output distortion
 2001 Consumer Microcircuits Limited
5
28
D/625/2
ISDN TA POTS Interface
CMX625
DTMF Decoder
Notes
Min.
Typ.
Max.
Unit
4
-29.0
-
-2.0
dBm
4
6
6,7
2
2
2
2
2
2
-9.0
±1.8
40.0
40.0
-
-14
20.0
-
-40.0
10.0
±4.5
0
40.0
45.0
20.0
dBm
dB
%
dB
dB
ms
ms
ms
ms
ms
ms
SPM Signal Level
Notes
Min.
Typ.
Max.
Unit
Level at SPM pin
4, 9
4, 9, 10
-1.5
-1.0
-14.0
-
0
0
1.2
10.0
1.0
0.5
14.0
-
dBm
dB
Hz
%
kΩ
Notes
Min.
Typ.
Max.
Unit
8
8
8
8
300
-0.5
-
0
30.0
3400
+0.5
-
Hz
dB
dB
dB
-
-
600
µs
-
-
1.5
0.75
0.25
1.5
ms
ms
ms
ms
22.0
27.0
33.0
33.0
-
-
dBp
dBp
dBp
dBp
-3.0
-1.0
-0.5
-0.5
-
1.0
+3.0
+1.0
+0.5
+0.5
-65.0
-
dB
dB
dB
dB
dBm0p
kΩ
Valid input signal levels
(each tone of composite signal)
Not decode level
(either tone of composite signal)
Twist = High Tone/Low Tone
Frequency Detect Bandwidth
Dial Tone Tolerance
Noise Tolerance
Tone Response time
Tone De-response time
Tone burst detected
Tone burst ignored
Pause length detected
Pause length ignored
Tone frequency accuracy
Tone output distortion
Output Impedance
5
PCM Codec-Filter
PCM Codec-Filter
Passband
Passband Gain (at 1.02kHz)
Passband Ripple (w.r.t. gain at 1.02kHz)
Stopband Attenuation
Group delay
Absolute
Relative to 1kHz:
500Hz
600Hz
2600Hz
2800Hz
Signal-to-total distortion ratio as a function of input
level (1kHz input level):
-45dBm
-40dBm
-30dBm
0dBm
Variation of gain with input level (1kHz input signal)
-55dBm0
-50dBm0
-40dBm0
+3dBm0
Idle channel noise
Output Impedance
 2001 Consumer Microcircuits Limited
29
11
11
11
11
11
D/625/2
ISDN TA POTS Interface
CMX625
Tx Output Buffer
Buffer output signal swing;
Load greater than 500Ω
Power-Up Timing
Device reset to reliable signal at TXO, TXON,
RING, SPM or TONEFSK output pins
Notes
Min.
Typ.
Max.
Unit
12
2.2
-
-
Vp-p
Notes
Min.
Typ.
Max.
Unit
-
50.0
-
ms
Notes:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
At 25°C, not including any current drawn from the CMX625 pins by external circuitry.
At nominal signal frequencies and without skew.
Excluding IOM-2 serial bus interface pins: FSC, DCL, DD and DU in bus reversal.
At VDD = 5.0V, load resistance greater than 40kΩ, signal levels are proportional to VDD.
Frequency above 300Hz.
Referenced to DTMF tone of lower amplitude.
Bandwidth limited: 0 to 3.4kHz Gaussian Noise.
See filter response, Figure 12.
SPM has a soft rise and fall time of about 4ms. The level changes between VBIAS and
0dBm in 2dB steps, 16 steps per rise and fall. When SPM is disabled, an extra 4ms
falling tail end of signal should be taken into consideration.
Over the range VDD = 3.3V to 5.5V at Tamb = 25°C.
Represents a psophometrically weighted measurement.
For each of the TXON (if enabled) and TXO pins, load placed between the pin and
VDD / 2, for VDD = 5.0V only.
Derate linearly minimum TTL Logic ‘0’ level from 0.8V at Vdd = 3.3V to 0.5V at
Vdd = 2.7V.
All outputs CMOS levels.
 2001 Consumer Microcircuits Limited
30
D/625/2
ISDN TA POTS Interface
CMX625
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
-1.2
-1.4
-1.6
-1.8
-2
0
500
1000
1500
2000
2500
3000
3500
Frequency (Hz)
Figure 12a Passband - PCM Codec-Filter overall frequency response
0
-10
-20
Gain (dB)
-30
-40
-50
-60
-70
-80
-90
-100
0
1000
2000
3000
4000
5000
6000
7000
8000
Frequency (Hz)
Figure 12b PCM Codec-Filter overall frequency response
 2001 Consumer Microcircuits Limited
31
D/625/2
ISDN TA POTS Interface
CMX625
IOM-2 Bus Timing (See Figure 13)
tDCL
tDCL
tR / tF
FSC
tFSCS
tFSCH
tDUDC
tDUDF
Notes:
DCL clock period in TE Mode
DCL clock period in non-TE Mode
DCL clock rise time / fall time
FSC period
FSC set-up time
FSC hold time
DU delay clock (data out)
DU delay frame (data out)
Notes
Min.
Typ.
Max.
Unit
1
1
-
651
244
-
ns
ns
1
-
-
60
ns
1
1
1
2
2
70
40
-
125
-
100
150
µs
ns
ns
ns
ns
1. These signals are requirements and are not under control of CMX625.
2. Condition CL = 150pF.
Figure 13 IOM-2 Bus Timing Diagram
Typical UART Timings (See Figures 9a and 9b)
TFSK
TDLY
TDRDY
TUFL
(delay through the modulator)
(1 bit period)
(¼ bit-period)
(¾ bit-period)
 2001 Consumer Microcircuits Limited
32
Notes
Min.
Typ.
Max.
Unit
-
106
833
208
625
-
µs
µs
µs
µs
D/625/2
ISDN TA POTS Interface
1.7.2
CMX625
Packaging
Figure 12 24-pin SSOP (D5) Mechanical Outline: Order as part no. CMX625D5
Figure 13 24-pin DIL (P4) Mechanical Outline: Order as part no. CMX625P4
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
CML Microcircuits
COMMUNICATION SEMICONDUCTORS
CML Product Data
In the process of creating a more global image, the three standard product semiconductor
companies of CML Microsystems Plc (Consumer Microcircuits Limited (UK), MX-COM, Inc
(USA) and CML Microcircuits (Singapore) Pte Ltd) have undergone name changes and, whilst
maintaining their separate new names (CML Microcircuits (UK) Ltd, CML Microcircuits (USA)
Inc and CML Microcircuits (Singapore) Pte Ltd), now operate under the single title CML Microcircuits.
These companies are all 100% owned operating companies of the CML Microsystems Plc
Group and these changes are purely changes of name and do not change any underlying legal
entities and hence will have no effect on any agreements or contacts currently in force.
CML Microcircuits Product Prefix Codes
Until the latter part of 1996, the differentiator between products manufactured and sold from
MXCOM, Inc. and Consumer Microcircuits Limited were denoted by the prefixes MX and FX
respectively. These products use the same silicon etc. and today still carry the same prefixes.
In the latter part of 1996, both companies adopted the common prefix: CMX.
This notification is relevant product information to which it is attached.
Company contact information is as below:
CML Microcircuits
(UK)Ltd
CML Microcircuits
(USA) Inc.
CML Microcircuits
(Singapore)PteLtd
COMMUNICATION SEMICONDUCTORS
COMMUNICATION SEMICONDUCTORS
COMMUNICATION SEMICONDUCTORS
Oval Park, Langford, Maldon,
Essex, CM9 6WG, England
Tel: +44 (0)1621 875500
Fax: +44 (0)1621 875600
[email protected]
www.cmlmicro.com
4800 Bethania Station Road,
Winston-Salem, NC 27105, USA
Tel: +1 336 744 5050,
0800 638 5577
Fax: +1 336 744 5054
[email protected]
www.cmlmicro.com
No 2 Kallang Pudding Road, 09-05/
06 Mactech Industrial Building,
Singapore 349307
Tel: +65 7450426
Fax: +65 7452917
[email protected]
www.cmlmicro.com
D/CML (D)/1 February 2002