DALLAS DS2181A

DS2181A
CEPT Primary Rate Transceiver
www.dalsemi.com
FEATURES
40
VDD
TFSYNC
2
39
RLOS
TCLK
3
38
RFER
TCHCLK
4
37
RBV
TSER
5
36
RCL
TMO
6
35
RNEG
Simple serial interface used for device
configuration and control in processor mode
Hardware mode requires no host processor;
intended for stand-alone applications
Comprehensive, on-chip alarm generation,
alarm detection, and error logging logic
Shares footprint with DS2180A T1
Transceiver
TXD
7
34
RPOS
TSTS
8
33
RST
TSD
9
32
TEST
TIND
10
31
RCSYNC
TAF
11
30
RSTS
TPOS
12
29
RSD
TNEG
13
28
RMSYNC
INT
14
27
RFSYNC
SDI
15
26
RSER
SDO
16
25
RCHCLK
CS
17
24
RCLK
SCLK
18
23
RAF
SPS
19
22
RDMA
VSS
20
21
RRA
Comparison to DS2175 T1/CEPT Elastic
Store, DS2186 Transmit Line Interface,
DS2187 Receive Line Interface, and DS2188
Jitter Attenuator
40-Pin DIP (600-mil)
RFSA
TCHCLK
TCLK
RMSA
TFSYNC
TMSYNC
VDD
RLOS
RFER
RBV
RCL
1
5V supply; low-power CMOS technology
TSER
TMO
TXD
TSTS
TSD
TIND
TAF
TPOS
TNEG
INT
SDI
5
4
3
2
1
44
43
42
41
Supports new CRC4-based framing
standards and CAS and CCS signaling
standards
TMSYNC
7
8
9
10
11
12
13
14
15
16
17
44-PIN PLCC
19
20
21
22
23
24
25
26
27
PIN ASSIGNMENT
Single chip primary rate transceiver meets
CCITT standards G.704, G.706 and G.732
39
38
37
36
35
34
33
32
31
30
29
RNEG
RPOS
RST
TEST
RCSYNC
RSTS
RSD
RMSYNC
RFSYNC
RSER
RCHCLK
SDO
CS
SCLK
SPS
VSS
RRA
RDMA
RCTO
RAF
RCLK
RCSA
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112099
DS2181A
DESCRIPTION
The DS2181A is designed for use in CEPT networks and supports all logical requirements of CCITT Red
Book Recommendations G.704, G.706 and G.732. The transmit side generates framing patterns and
CRC4 codes, formats outgoing channel and signaling data, and produces network alarm codes when
enabled. The receive side decodes the incoming data and establishes frame, CAS multiframe, and CRC4
multiframe alignments. Once synchronized, the device extracts channel, signaling, and alarm data.
A serial port allows access to 14 on-chip control and status registers in the processor mode. In this mode,
a host processor controls features such as error logging, per-channel code manipulation, and alteration of
the receive synchronizer algorithm.
The hardware mode is intended for preliminary system prototyping and/or retrofitting into existing
systems. This mode requires no host processor and disables special features available in the processor
mode.
DS2180A BLOCK DIAGRAM Figure 1
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DS2181A
TRANSMIT PIN DESCRIPTION (40-PIN DIP ONLY) Table 1
PIN
1
SYMBOL
TMSYNC
TYPE
I
2
TFSYNC
I
3
4
TCLK
TCHCLK
I
O
5
TSER
I
6
TMO
O
7
TXD
I
8
TSTS
O
9
TSD
I
10
TIND
I
11
TAF
O
12
13
TPOS
TNEG
O
DESCRIPTION
Transmit Multiframe Sync. Low-high transition establishes start of
CAS and/or CRC4 multiframe. Can be tied low, allowing internal
multiframe counter to run free.
Transmit Frame Sync. Low-high transition every frame period
establishes frame boundaries. Can be tied low, allowing TMSYNC to
establish frame boundaries.
Transmit Clock. 2.048 MHz primary clock.
Transmit Channel Clock. 256 kHz clock which identifies timeslot
boundaries. Useful for parallel-to-serial conversion of channel data.
Transmit Serial Data. NRZ data input, sampled on falling edges of
TCLK.
Transmit Multiframe Out. Output of multiframe counter; high
during frame 0, low otherwise.
Transmit Extra Data. Sampled on falling edge of TCLK during bit
times 5, 7, and 8 of timeslot 16 in frame 0 when CAS signaling is
enabled.
Transmit Signaling Timeslot. High during timeslot 16 of every
frame, low otherwise.
Transmit Signaling Data. CAS signaling data input; sampled on
falling edges of TCLK for insertion into outgoing timeslot 16 when
enabled.
Transmit International and National Data. Sampled on falling
edge of TCLK during bit 1 time of timeslot 0 every frame
(international) and/or during bit times 4 through 8 of timeslot 0 during
non-align frames (national) when enabled.
Transmit Alignment Frame. High during frames containing the
frame alignment signal, low otherwise.
Transmit Bipolar Data Outputs. Updated on rising edge of TCLK.
SYCHRONIZER STATUS PIN (44-PIN PLCC ONLY) Table 2A
PIN
3
SYMBOL
RMSA
TYPE
O
6
RFSA
O
25
RCTO
O
28
RCSA
O
DESCRIPTION
Receive Multiframe Search Active. This pin will transition high
when the synchronizer searching for the CAS multiframe alignment
word is active.
Receive Frame Search Active. This pin will transition high when the
synchronizer searching for the FAS is active.
Receive CRC4 Time Out. This pin will transition high when the
RCTO counter reaches its maximum count of 32. The pin will return
low when either the DS2181AQ reaches CRC4 multiframe
synchronization, or if CRC4 is disabled via CRC.2, or if the device is
issued a hardware reset via the RST pin.
Receive CRC4 Search Active. This pin will transition high when the
synchronizer searching for the CRC4 multiframe alignment word is
active.
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DS2181A
NOTES:
1. These output status pins are only available on the DS2181AQ.
2. If the TEST pin is tied low and CCR.1=0, then these pins will be tri–stated.
RECEIVE PIN DESCRIPTION (40-PIN DIP ONLY) Table 2B
PIN
21
SYMBOL
RRA
TYPE
O
22
RMDA
O
23
RAF
O
24
25
RCLK
RCHCLK
I
O
26
RSER
O
27
28
RFSYNC
RMSYNC
O
O
29
RSD
O
30
RSTS
O
31
RCSYNC
O
33
RST
I
34
35
36
37
RPOS
RNEG
RCL
RBV
I
O
O
38
RFER
O
39
RLOS
O
DESCRIPTION
Receive Remote Alarm. Transitions high when alarm detected;
returns low when alarm cleared.
Receive Distant Multiframe Alarm. Transitions high when alarm
detected; returns low when alarm cleared.
Receive Alignment Frame. High during frames containing the frame
alignment signal, low otherwise.
Receive Clock. 2.048 MHz primary clock.
Receive Channel Clock. 256 kHz clock, identifies timeslot
boundaries; useful for serial-to-parallel conversion of channel data.
Receive Channel Clock. 256 kHz clock, identifies timeslot
boundaries; useful for serial-to-parallel conversion of channel data.
Receive Frame Sync. Trailing edge indicates start of frame.
Receive Multiframe Sync. Low-high transition indicates start of
CAS multiframe; held high during frame 0.
Receive Signaling Data. Extracted timeslot 16 data; updated on
rising edge of RCLK.
Receive Signaling Timeslot. High during timeslot 16 of every frame,
low otherwise.
Receive CRC4 Sync. Low-high transition indicates start of CRC4
multiframe; held high during CRC4 frames 0 through 7 and held low
during frames 8 through 15.
Reset. Must be asserted during device power-up and when changing
to/from the hardware mode.
Receive Bipolar Data. Sampled on falling edges of RCLK. Tie
together to receive NRZ data and disable BPV monitor circuitry.
Receive Carrier Loss. Low-high transition indicates loss of carrier.
Receive Bipolar Violation. Pulses high during detected bipolar
violations.
Receive Frame Error. Pulses high when frame alignment, CAS
multiframe alignment or CRC4 words received in error.
Receive Loss of Sync. Indicates synchronizer status; high when
frame, CAS and/or CRC4 multiframe search underway, low
otherwise.
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DS2181A
PORT PIN DESCRIPTION (40-PIN DIP ONLY) Table 3
PIN
14
SYMBOL
INT
TYPE
O
15
SDI
I
16
SDO
O
17
CS
I
18
19
SCLK
SPS
I
I
DESCRIPTION
Receive Alarm Interrupt. Flags host controller during alarm
conditions. Active low; open drain output.
Serial Data In. Data for on-chip control registers; sampled on rising
edge of SCLK.
Serial Data Out. Control and status data from on-chip registers.
Updated on falling edge of SCLK; tri-stated during port write or when
CS is high.
Chip Select. Must be low to write or read the serial port.
Serial Data Clock. Used to write or read the serial port registers.
Serial Port Select. Tie to VDD to select the serial port. Tie to VSS to
select the hardware mode.
POWER AND TEST PIN DESCRIPTION (40-PIN DIP ONLY) Table 4
PIN
20
32
SYMBOL
VSS
TEST
TYPE
I
40
VDD
-
DESCRIPTION
Signal Ground. 0.0 volts.
Test Mode. Tie to VSS to select the old DS2181 sync algorithm and to
tri–state the synchronizer status pins on the DS2181AQ. Tie to VDD
to select the new DS2181A sync algorithm and activate the
synchronizer status pins on the DS2181AQ.
Positive Supply. 5.0 volts.
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DS2181A
REGISTER SUMMARY Table 5
REGISTE
R
RIMR
ADDRE
SS
0000
T/R1
DESCRIPTION/FUNCTION
R
RSR
BVCR
0001
0010
R2
R
CECR
0011
R
FECR
0100
R
RCR
0101
R
CCR
0110
T/R
TCR
0111
T
TIR1
TIR2
TIR3
TIR4
TINR
1000
1001
1010
1011
1100
T
Receive Interrupt Mask Register. Allows masking of alarm
generated interrupts.
Receive Status Register. Reports all receive alarm conditions.
Bipolar Violation Count Register. 8-bit presettable counter
which records individual bipolar violations.
CRC4 Error Count Register. 8-bit presettable counter which
records individual errors.
Frame Error Count Register. 8-bit presettable counter which
logs individual errors in the received frame alignment signal.
Receive Control Register. Establishes receive side operating
characteristics.
Common Control Register. Establishes additional operating
characteristics for transmit and receive sides.
Transmit Control Register. Establishes transmit side operation
characteristics.
Transmit Idle Registers. Designates which outgoing timeslots are
to be substituted with idle code.
T
TXR
1101
T
Transmit International and National Register. When enabled via
the TCR, contents inserted into the outgoing national and/or
international bit positions.
Transmit Extra Register. When enabled via the TCR, contents
inserted into the out going extra bit positions.
NOTES:
1. Transmit or receive side register.
2. RSR is a read only register; all other registers are read/write.
3. Reserved bit locations must be programmed to 0.
SERIAL PORT INTERFACE
Pins 14 through 18 of the DS2181A serve as a microprocessor/ microcontroller-compatible serial port.
Fourteen on-chip registers allow the user to update operational characteristics and monitor device status
via a host controller, minimizing hardware interfaces.
Port read/write timing is unrelated to the chip transmit and receive timing, allowing asynchronous reads
and/ or writes by the host. The timing set is identical to that of 8051-type microcontrollers operating in
serial port mode 0. For proper operation of the port and the transmit and receive registers, the user should
provide TCLK and RCLK as well as SCLK.
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DS2181A
ADDRESS/COMMAND
An address/command byte write must precede any read or write of the port registers. The first bit written
(LSB) of the address/command byte specifies read or write. The following nibble identifies register
address. The next 2 bits are reserved and must be set to 0 for proper operation. The last bit of the
address/command word enables the burst mode when set; the burst mode allows consecutive reading or
writing of all register data. Data is written to and read from the port LSB first.
CHIP SELECT AND CLOCK CONTROL
All data transfers are initiated by driving the CS input low. Data is sampled on the rising edge of SCLK.
Data is output on the falling edge of SCLK and held to the next falling edge. All data transfers are
terminated and SDO tri-stated when CS returns to high.
CLOCKS
To access the serial port registers both TCLK and RCLK are required along with the SCLK. The TCLK
and RCLK are used to internally access the transmit and receive registers, respectively. The CCR is
considered a receive register for this purpose.
DATA I/O
Following the eight SCLK cycles that input the address/ command byte, data at SDI is strobed into the
addressed register on the next eight SCLK cycles (register write) or data is presented at SDO on the next
eight SCLK cycles (register read). SDO is tri-stated during writes and may be tied to SDI in applications
where the host processor has bi-directional I/O capability.
BURST MODE
The burst mode allows all on-chip registers to be consecutively read or written by the host processor. This
feature minimizes device initialization time on system power-up or reset. Burst mode is initiated when
ACB.7 is set and the address nibble is 0000. All registers must be read or written during the burst mode.
If CS transitions high before the burst is complete, data validity is not guaranteed.
ACB: ADDRESS COMMAND BYTE Figure 2
(MSB)
BM
(LSB)
-
-
SYMBOL
POSITION
BM
ACB.7
ADD3
ADD2
ADD1
ADD0
R/W
ACB.6
ACB.5
ACB.4
ACB.3
ACB.2
ACB.1
ACB.0
ADD3
ADD2
ADD1
AD0
R/W
NAME AND DESCRIPTION
Burst Mode. If set (and ACB.1 through ACB.4=0) burst read or
write is enabled.
Reserved, must be 0 for proper operation.
Reserved, must be 0 for proper operation.
MSB of register address.
LSB of register address.
Read/Write Select.
0 = write addressed register.
1 = read addressed register.
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DS2181A
SERIAL PORT READ/WRITE Figure 3
NOTES:
1. SDI sampled on rising edge of SCLK.
2. SDO updated on falling edge of SCLK.
TCR: TRANSMIT CONTROL REGISTER Figure 4
(MSB)
TUA1
TSS
TSM
SYMBOL
POSITION
TUA1
TCR.7
TSS
TCR.6
TSM
TCR.5
INBS
TCR.4
NBS
TCR.3
XBS
TCR.2
TSA1
TCR.1
ODM
TCR.0
INBS
NBS
(LSB)
XBS
TSA1
ODM
NAME AND DESCRIPTION
Transmit Unframed All 1’s.
0 = Normal operation.
1 = Replace outgoing data at TPOS and TNEG with unframed all
1’s code.
Transmit Signaling Select1
0 = Signaling data embedded in the serial bit stream is sampled at
TSER during timeslot 16.
1 = Signaling data is channel associated and sampled at TSD as
shown in Table 6.
Transmit Signaling Mode1
0 = Channel Associated Signaling (CAS).
1 = Common Channel Signaling (CCS).
International Bit Select
0 = Sample international bit at TIND.
1 = Outgoing international bit = TINR.7.
National Bit Select
0 = Sample national bits at TIND.
1 = Source outgoing national bits from TINR.4 through TINR.0.
Extra Bit Select
0 = Sample extra bits at TXD.
1 = Source extra bits from TXR.0 through TXR.1 and TXR.3.
Transmit Signaling All 1’s
0 = Normal operation.
1 = Force contents of timeslot 16 in all frames to all 1’s.
Output Data Mode
0 = TPOS and TNEG outputs are 100% duty cycle.
1 = TPOS and TNEG outputs are 50% duty cycle.
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DS2181A
NOTE:
1. When the common channel signaling mode is enabled (TCR.5 = 1), the TSD input is disabled
internally; all timeslot 16 data is sampled at TSER.
CCR: COMMON CONTROL REGISTER Figure 5
(MSB)
-
TAFP
THDE
SYMBOL
POSITION
TAFP
CCR.7
CCR.6
THDE
CCR.5
RHDE
CCR.4
TCE
CCR.3
RCE
CCR.2
SAS
CCR.1
LLB
CCR.0
RHDE
TCE
(LSB)
RCE
SAS
LLB
NAME AND DESCRIPTION
Reserved; must be 0 for proper operation.
Transmit Align Frame Position1
When clear, the CAS multiframe begins with a frame containing
the frame alignment signal. When set, the CAS multiframe begins
with a frame not containing the frame alignment signal.
Transmit HDB3 Enable
0 = Outgoing data at TPOS and TNEG is AMI coded.
1 = Outgoing data at TPOS and TNEG is HDB3 coded.
Receive HDB3 Enable
0 = Incoming data at RPOS and RNEG is AMI coded.
1 = Incoming data is RPOS and RNEG is HDB3 coded.
Transmit CRC4 Enable
When set, outgoing international bit positions in frames 0 through
12 and 14 are replaced by CRC4 multiframe alignment and
checksum words.
Receive CRC4 Enable
0 = Disable CRC4 multiframe synchronizer.
1 = Enable CRC4 synchronizer; search for CRC4 multiframe
alignment once frame alignment complete.
Sync Algorithm Select
0 = Use old DS2181 sync algorithm
1 = Use new DS2181A sync algorithm
Local Loopback
0 = Normal operation.
1 = Internally loop TPOS, TNEG, and TCLK to RPOS, RNEG,
and RCLK.
NOTES:
1. This bit must be cleared when CRC4 multiframe mode is enabled (CCR.3 = 1); its state does not
affect CCS framing (RCR.5 = 1).
2. CCR is considered a receive register and operates from RCLK and SCLK.
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DS2181A
RCR: RECEIVE CONTROL REGISTER Figure 6
(MSB)
-
-
RSM
SYMBOL
POSITION
RSM
RCR.7
RCR.6
RCR.5
CMSC
RCR.4
CMRC
RCR.3
FRC
RCR.2
SYNCE
RCR.1
RESYNC
RCR.0
CMSC
CMRC
(LSB)
FRC
SYNCE
RESYNC
NAME AND DESCRIPTION
Reserved; must be 0 for proper operation.
Reserved; must be 0 for proper operation.
Received Signaling Mode
0 = Channel Associated Signaling (CAS).
1 = Common Channel Signaling (CCS).
CAS Multiframe Sync Criteria
0 = Declare sync when fixed sync criteria met.
1 = Declare sync when fixed criteria are met and two additional
consecutive valid multiframe alignment signals are detected.
CAS Multiframe Resync Criteria
0 = Utilize only fixed resync criteria.
1 = Resync if fixed criteria met and/or if two consecutive timeslot
16 words have values of 0 in the first four MSB positions
(0000xxxx).
Frame Resync Criteria
0 = Utilize only fixed resync criteria.
1 = Resync if fixed criteria met and/or if bit 2 in timeslot 0 of nonalign frames is received in error on three consecutive occasions.
Sync Enable
If clear, the synchronizer will automatically begin resync if error
criteria are met. If high, no auto resync occurs.
Resync
When toggled low to high, the receive synchronizer will initiate
immediately. The bit must be cleared, then set again for
subsequent resyncs.
CEPT FRAME STRUCTURE
The CEPT frame is made up of 32 8-bit channels (time-slots) numbered from 0 to 31. The frame
alignment signal in bit positions 2 through 8 of timeslot 0 of every other frame is independent of the
various multiframe modes described below. Outputs TAF and RAF indicate frames which contain the
alignment signal. Timeslot 0 of frames not containing the frame alignment signal is used for alarm and
national data. See the separate DS2181A CEPT Transceiver Application Note for more details.
CAS SIGNALLING
CEPT networks support Channel Associated Signaling (CAS) or Common Channel Signaling (CCS).
These signaling modes are independently selectable for transmit and receive sides.
CAS (selected when TCR.5 = 0 and/or when RCR.5 = 0) is a bit-oriented signaling technique which
utilizes a 16-frame multiframe. The multiframe alignment signal (0-hex), extra and alarm bits occupy
timeslot 16 of frame 0. Timeslot 16 of the remaining 15 frames is reserved for channel signaling data.
Four signaling bits (A, B, C and D) are transmitted once per multiframe as shown in Figure 7. Input
TMSYNC establishes the transmitted CAS multiframe position. Signaling data can be sourced from input
TSD (TCR.6 = 1) or multiplexed into TSER (TCR.6 = 0).
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DS2181A
CCS SIGNALLING
CCS (selected when TCR.5 = 1 and/or when RCR.1 = 1) utilizes all bit positions of timeslot 16 in every
frame for message-oriented signaling data transmission. In CCS mode one can use either timeslot 16 or
any one of the other 30 data channels for message-oriented signaling. The CCS mode has no multiframe
structure and the insertion of CAS multiframe alignment, distant multiframe alarm and/or extra bits into
timeslot 16 is disabled. TSER is the source of timeslot 16 data.
CRC4 CODING
The need for enhanced error monitoring capability and additional protection against emulators of the
frame alignment word has led to the development of a cyclic redundancy check (CRC) procedure. When
enabled via CCR.2 and/or CCR.3, CRC4 coding replaces the international bit positions in frames 0
through 12 and 14 with a CRC4 multiframe alignment pattern and associated checksum words. The
CRC4 multiframe must begin with a frame containing the frame alignment signal (CCR.6 = 0). A rising
edge at TMSYNC establishes the CRC4 multiframe alignment (TMSYNC will also establish outgoing
CAS multiframe alignment if enabled via TCR.5).
Incoming CRC4 multiframe alignment is indicated by RCSYNC. Detected CRC4 checksum errors are reported at output RFER and logged in the CECR.
RECEIVE SYNCHRONIZER
The fixed characteristics of the receive synchronizer may be modified by use of programmable
characteristics resident in the RCR and CCR. Sync criteria must be met before synchronization is
declared. Resync criteria establish error occurrences which will cause an auto-resync event when enabled
(RCR.1 = 0).
The receive synchronizer searches for the frame alignment pattern first. Once identified, the output timing
set associated with the framing pattern (all outputs except RCSYNC and RMSYNC) is updated to that
new alignment. If enabled, the synchronizer then begins CAS and/or CRC4 multiframe search; outputs
RMSYNC and/or RCSYNC are then updated. Output RLOS is held high during the entire resync process,
then transitions low after the last output timing update indicating resync is complete. For more details
about the receive synchronizer, see the separate DS2181A CEPT Transceiver Application Note.
FIXED FRAME SYNC CRITERIA
Valid frame sync is assumed when the correct frame alignment signal is present in frame N and frame N
+ 2 and not present in frame N + 1 (bit 2 of timeslot 0 of Frame N + 1 is also checked for 1). CAS and/or
CRC4 multiframe alignment search is initiated when the frame search is complete if enabled via RCR.5
and/or CCR.2.
FIXED CAS MULTIFRAME SYNC CRITERIA
CAS multiframe sync is declared when the multiframe alignment pattern is properly detected and timeslot
16 of the previous frame contains code other than zeros. If no valid pattern can be found in 12 to 14
milliseconds (no time-out period exists if CCR.1=1 or TEST=1), frame search is restarted.
FIXED CRC4 MULTIFRAME SYNC CRITERIA
CRC4 multiframe sync is declared if at least two valid CRC4 multiframe alignment signals are found
within 12 to 14 milliseconds (8 ms if CCR.1=1 or TEST=1) after frame alignment is completed. If not
found within 12 to 14 milliseconds (8 ms if CCR.1=1 or TEST=1), frame search is restarted. The search
for the multiframe alignment signal is performed in timeslot 0 of frames not containing the frame
alignment signal.
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DS2181A
FIXED FRAME RESYNC CRITERIA
When enabled via RCR.1, the device will automatically initiate frame search whenever the frame
alignment word is received in error three consecutive times.
FIXED CAS MULTIFRAME RESYNC CRITERIA
When enabled via RCR.1, the device will automatically initiate frame search whenever two consecutive
CAS multiframe alignment words are received in error.
FIXED CRC4 RESYNC CRITERIA
If CCR.1=1 or if the TEST pin is tied high, then the DS2181A will initiate the resync at the FAS level if
915 or more CRC4 words out of 1000 are received in error.
CAS SIGNALLING SOURCE
CAS applications sample signaling data at TSER when TCR.6 = 0; an on-chip data multiplexer accepts
channel-associated data input at TSD when TCR.6 = 1. The data multiplexer must be disabled (TCR.6 =
0) when the CCS mode is enabled (TCR.5 = 1).
TSD INPUT TIMING (TCR.6 = 1; TCR.5 = 0) Table 6
FRAME #
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
TIMESLOT SIGNALING
DATA SAMPLED AT TSD
17
1, 18
2, 19
3, 20
4, 21
5, 22
6, 23
7, 24
8, 25
9, 26
0, 27
11, 28
12, 29
13, 30
14, 31
15
NOTE:
1. A, B, C and D data is sampled on falling edges of TCLK during bit times 5, 6, 7 and 8 of timeslots
indicated.
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DS2181A
TSD INPUT TIMING Figure 7
CAS OUTPUT FORMAT IN TIMESLOT 16 Figure 8
FRAME 01
0000XYXX
FRAME 1
ABCD for
Timeslot 1
FRAME 15
ABCD for
timeslot 17
ABCD for
Timeslot 15
ABCD for
Timeslot 31
NOTE:
1. Timeslot 16 of frame 0 is reserved for the multiframe alignment word (0000), distant multiframe
alarm (Y) and extra bits (X-XX).
TINR: TRANSMIT INTERNATIONAL AND NATIONAL REGISTER Figure 9
(MSB)
(LSB)
INB
-
TRA
SYMBOL
POSITION
INB
TINR.7
TRA
TINR.6
TINR.5
NB4
TINR.4
NB5
NB6
NB7
NB8
TINR.3
TINR.2
TINR.1
TINR.0
NB4
NB5
NB6
NB7
NB8
NAME AND DESCRIPTION
International Bit. Inserted into the outgoing data stream when
TCR.4 = 1.
Reserved; must be 0 for proper operation.
Transmit Remote Alarm
0 = Normal operation; bit 3 of timeslot 0 in non-alignment frame
clear.
1 = Alarm condition; bit 3 of timeslot 0 in non-align frames set.
Transmit National Bits. Inserted into the outgoing data stream at
TPOS and TNEG when TCR.3 = 1.
TRANSMIT INTERNATIONAL AND NATIONAL DATA
Bit 1 of timeslot 0 in all frames is known as the international bit. When TCR.4 = 1, the transmitted
international bit is sourced from TINR.7. When TCR.4 = 0, the transmitted international bit is sampled at
TIND during the first bit period of each frame. The international bit positions in all outgoing frames
except 13 and 15 are replaced by CRC4 code words and the CRC4 multiframe alignment signal when
CCR.3 = 1.
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DS2181A
Bits 4 through 8 of timeslot 0 in non-align frames are reserved for national use. When TCR.3 = 1, the
transmitted national bits are sourced from register locations TINR.4 through TINR.0. If TCR.3 = 0, the
national bits are sampled at TIND during bit times 4 through 8 of timeslot 0 in non-align frames.
Reserved bit positions in the TINR must be set to 0 when written; those bits can be 0 or 1 when read.
TXR: TRANSMIT EXTRA REGISTER Figure 10
(MSB)
-
-
-
SYMBOL
POSITION
XB1
TDMA
TXR.7
TXR.6
TXR.5
TXR.4
TXR.3
TXR.2
XB2
XB3
TXR.1
TXR.0
-
XB1
(LSB)
TDMA
XB2
XB3
NAME AND DESCRIPTION
Reserved; must be 0 for proper operation.
Reserved; must be 0 for proper operation.
Reserved; must be 0 for proper operation.
Reserved; must be 0 for proper operation.
Extra Bit 1
Transmit Distant Multiframe Alarm
0 = Normal operation; bit 6 of timeslot 16 in frame 0 clear.
1 = Alarm condition; bit 6 of timeslot 16 in frame 0 set.
Extra Bit 2
Extra Bit 3
TRANSMIT EXTRA DATA
In the CAS mode, timeslot 16 of frame 0 contains the multiframe alignment pattern, extra bits and the
distant multiframe alarm. When CAS is enabled (TCR.5 = 0), the extra bits are sourced from TXR.0,
TXR.1 and TXR.3 (TCR.2 = 1) or the extra bits are sampled externally at TXD during the extra bit time
(TCR.2 = 0). The extra bits, alignment pattern and alarm signal are not utilized in the CCS mode (TCR.5
= 1); input TSER overwrites all timeslot 16 bit positions.
Reserved bit positions in the TXR must be set to 0 when written; those bits can be 0 or 1 when read.
TIR1 - TIR4: TRANSMIT IDLE REGISTERS Figure 11
(MSB)
(LSB)
TS7
TS6
TS5
TS4
TS3
TS2
TS1
TS01
TIR1
TS15
TS14
TS13
TS12
TS11
TS10
TS9
TS8
TIR2
1
TIR3
TIR4
TS23
TS22
TS21
TS20
TS19
TS18
TS17
TS16
TS31
TS30
TS29
TS28
TS27
TS26
TS25
TS024
SYMBOL
POSITION
TS31
TS0
TIR4.7
TIR1.0
NAME AND DESCRIPTION
Transmit Idle Registers
Each of these bit positions represents a timeslot in the outgoing
stream at TPOS and TNEG; when set, the contents of that timeslot
are forced to idle code (11010101).
NOTE:
1. TS0 and TS16 are not affected by the idle register.
14 of 32
DS2181A
TRANSMIT TIMING
A low-high transition at TMSYNC once per multiframe (every 2 milliseconds) or at a multiple of the
multiframe rate establishes outgoing CAS and/or CRC4 multiframe alignment. Output TMO indicates
that alignment. A low-high transition at TFSYNC at the frame rate (125 us) or at a multiple of the frame
rate establishes the outgoing frame position. Output TAF indicates that alignment. TMSYNC and/or
TFSYNC can be tied low by the user, in which case the arbitrary frame and multiframe alignment
established by the device will be indicated at TMO and TAF.
Output TAF also indicates frames containing the frame alignment signal. Those frames can be even or
odd numbering frames of the outgoing CAS multiframe (CCR.6).
TRANSMIT MULTIFRAME TIMING Figure 12
NOTES:
1. Alignment frames are even frames of the CAS and/or CRC4 multiframes (CCR.6 = 0).
2. Alignment frames are odd frames of the CAS multiframe (CCR.6 = 1).
15 of 32
DS2181A
TRANSMIT MULTIFRAME BOUNDARY TIMING Figure 13
NOTES:
1. Low-high transitions on TMSYNC and/or TFSYNC must occur one TCLK period early with respect
to actual frame and multiframe boundaries. TMO follows the rising edge of TMSYNC or TFSYNC.
2. TAF transitions on true frame boundaries.
3. Delay from TSER to TPOS, TNEG is five TCLK periods.
TRANSMIT SIGNALING TIMESLOT TIMING Figure 14
RECEIVE SIGNALING
Receive signaling data is available at two outputs: RSER and RSD. RSER outputs the signaling data in
timeslot 16 at RSER. The signaling data is also extracted from timeslot 16 and presented at RSD during
the timeslots shown in Table 7. This channel-associated signaling simplifies CAS system design.
16 of 32
DS2181A
RECEIVE SIGNALING Table 7
FRAME #
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
RSD1 VALID DURING
TIMESLOT #
15, -2
-2
, 17
1, 18
2, 19
3, 20
4, 21
5, 22
6, 23
7, 24
8, 25
9, 26
10, 27
11, 28
12, 29
13, 30
14, 31
NOTES: (Applicable only to CAS systems)
1. RSD is valid for the least significant nibble in each indicated timeslot. Timeslot A data appears in bit
5, B in bit 6, C in bit 7 and D in bit 8.
2. RSD does not output valid data during timeslots 0 and 16.
RECEIVE MULTIFRAME TIMING Figure 15
RECEIVE TIMING
The receive side output timing set is identical to that found on the transmit side. The user can tie receive
outputs directly to the transmit inputs for drop and insert applications. The received data of RPOS, RNEG
appear at RSER after six RCLK delays, without any change except for the HDB3-to-NRZ conversion
when HDB3 is enabled.
17 of 32
DS2181A
NOTE:
1. The CAS multiframe can start with an align or non-align frame. The CRC4 multiframe always starts
with an align frame.
RSD TIMING Figure 16
18 of 32
DS2181A
RECEIVE MULTIFRAME BOUNDARY TIMING Figure 17
NOTES:
1. Low-high transitions on RMSYNC and RFSYNC occur one RCLK period early with respect to actual
frame and multiframe boundaries.
2. RAF transitions on true frame boundaries.
3. Delay from RPOS, RNEG to RSER is six RCLK periods.
4. RMSYNC and RCSYNC transition low on the falling edge of RFSYNC.
19 of 32
DS2181A
RSR: RECEIVE STATUS REGISTER Figure 18
(MSB)
RRA
RDMA
RSA1
SYMBOL
POSITION
RRA
RSR.7
RDMA
RSR.6
RSA1
RSR.5
RUA1
RSR.4
FSERR
RSR.3
MFSERR
RSR.2
RLOS
ECS
RSR.1
RSR.0
RUA1
FSERR
(LSB)
MFSERR
RLOS
ECS
NAME AND DESCRIPTION
Receive Remote Alarm. Set when bit 3 of timeslot 0 in non-align
frames set for three consecutive non-align frames.
Receive Distant Multiframe Alarm. Set when bit 6 of timeslot 16
in frame 0 is set for three consecutive multiframes.
Receive Signaling All Ones. Set when the contents of timeslot 16
have been all 1's for two consecutive frames.
Receive Unframed All Ones. Set when less than three 0s have
been received in the last two consecutive frames.
Frame Resync Criteria Met. Set when the frame error criteria are
met; also the frame resync is initiated if RCR.1=0.
CAS Multiframe Resync Criteria Met. Set when the CAS
multiframe error criteria are met; also, the frame resync is initiated
if RCR.1=0.
Receive Loss of Sync. Set when resync is in progress.
Error Counter Saturation. Set when any of the on-chip counters
at FECR, CECR or BVCR saturates.
NOTE:
1. When in the CCS mode, the RDMA flag bit and the RDMA pin have no significance. It will be set
when bit 6 of timeslot 16 in frame 0 is set for three consecutive multiframes in either CAS or CCS
mode.
20 of 32
DS2181A
RIMR: RECEIVE INTERRUPT MASK REGISTER Figure 19
(MSB)
RRA
RDMA
RSA1
SYMBOL
POSITION
RRA
RIMR.7
RDMA
RIMR.6
RSA1
RIMR.5
RUA1
RIMR.4
FSERR
RIMR.3
MFSERR
RIMR.2
RLOS
RIMR.1
ECS
RIMR.0
RUA1
FSERR
MFSERR
(LSB)
RLOS
ECS
NAME AND DESCRIPTION
Receive Remote Alarm
1 = Interrupt enabled
0 = Interrupt masked
Receive Distant Multiframe Alarm
1 = Interrupt enabled
0 = Interrupt masked
Receive Signaling All 1’s
1 = Interrupt enabled
0 = Interrupt masked
Receive Unframed All 1’s
1 = Interrupt enabled
0 = Interrupt masked
Frame Resync Criteria Met
1 = Interrupt enabled
0 = Interrupt masked
CAS Multiframe Resync Criteria Met
1 = Interrupt enabled
0 = Interrupt masked
Receive Loss of Sync
1 = Interrupt enabled
0 = Interrupt masked
Error Count Saturation
1 = Interrupt enabled
0 = Interrupt masked
ALARM REPORTING AND INTERRUPT SERVICING
Alarm and error conditions are reported at outputs and the RSR. Use of the RSR and error count registers
simplifies system error monitoring. The RSR can be read in one of two ways: a burst read does not
disturb the RSR contents; a direct read will clear all bits set in the RSR unless the alarm condition which
set them is still active. Interrupts are enabled via the RIMR and are generated whenever an alarm or error
condition sets an RSR bit. The host controller must service the transceiver in order to clear an interrupt
condition. Clearing the appropriate RIMR bit will unconditionally clear an interrupt.
BVCR: BIPOLAR VIOLATION COUNT REGISTER Figure 20
(MSB)
BVD7
BVD6
BVD5
SYMBOL
POSITION
BVD7
BVD0
BVCR.7
BVCR.0
BVD4
BVD3
BVD2
NAME AND DESCRIPTION
MSB of bipolar violation count.
LSB of bipolar violation count.
21 of 32
(LSB)
BVD1
BVD0
DS2181A
CECR: CRC4 ERROR COUNT REGISTER Figure 21
(MSB)
CRC7
CRC6
CRC5
SYMBOL
POSITION
CRC7
CRC0
BVCR.7
BVCR.0
CRC4
CRC3
(LSB)
CRC2
CRC1
NAME AND DESCRIPTION
MSB of CRC4 error count.
LSB of CRC4 error count.
FECR: FRAME ERROR COUNT REGISTER Figure 22
(MSB)
FE7
FE6
FE5
SYMBOL
POSITION
FE7
FE0
FECR.7
FECR.0
CRC0
FE4
FE3
FE2
(LSB)
FE1
FE0
NAME AND DESCRIPTION
MSB of frame error count.
LSB of frame error count.
ERROR LOGGING
The BVCR, CECR and FECR contain 8-bit binary up counters which increment on individual bipolar
violations, CRC4 code word errors (when CCR.2 = 1), and word errors in the frame alignment signal.
Each counter saturates at 255. Once saturated, each following error occurrence will generate an interrupt
(RIMR.0 = 1) until the register is reprogrammed to a value other than FF (hex). Presetting the registers
allows the user to establish specific error count thresholds; the counter will count up to saturation from
the preset value. The BVCR increments at all times (regardless of sync status), except when HDB3 code
words are received with CCR.4=1. CECR and FECR increments are disabled whenever resync is in
progress (RLOS high).
ALARM OUTPUTS
Alarm conditions are also reported real time at alarm outputs. These outputs can be used with off-chip
logic to complement the on-chip error reporting capability of the DS2181A. In the hardware mode, they
are the only alarm reporting means available.
RLOS
The RLOS output indicates the status of the receive synchronizer. When high, frame, CAS multiframe
and/or CRC4 multiframe synchronization is in progress. A high-low transition indicates resync is
complete. The RLOS bit (RSR.1) is a latched version of the RLOS output.
RRA
The remote alarm output transitions high when a remote alarm is detected. A high-low transition indicates
the alarm condition has been cleared. The alarm condition is defined as bit 3 of time slot 0 set for three
consecutive non-align frames. The alarm state is cleared when bit 3 has been clear for three consecutive
non-align frames. The RRA bit (RSR.7) is a latched version of the RRA Output.
RBV
RBV pulses high when the accused bit emerges at RSER. RBV will return low when RCLK goes low.
Bipolar violations are also logged in the BVCR. The RBV pin provides a pulse for every violation which
can be counted externally.
22 of 32
DS2181A
RDMA
RDMA transitions high when bit 6 of timeslot 16 in frame 0 is set for three consecutive occasions and
returns low when the bit is clear for three consecutive occasions. The RDMA bit (RSR.6) is a latched
version of the RDMA output.
RCL
RCL transitions high after 32 consecutive 0s appear at RPOS and RNEG; it goes low at the next 1
occurrence.
RFER
The RFER output transitions high when received frame alignment, CAS multiframe alignment and/or
CRC4 code words are in error. The FECR and CECR log error events reported at this output. FECR logs
only the frame alignment word errors. CECR logs CRC4 code word errors.
To complement the on-chip error logging capabilities of the DS2181A, the system designer can use offchip logic gated by receive side outputs RCHCLK, RAF, RSTS and RCSYNC to demux error states
present at RFER. See the separate DS2181A CEPT Transceiver Application Note for more details.
RFER OUTPUT TIMING FOR ALL ERROR CONDITIONS Figure 23
CAS MULTIFRAME ALIGNMENT ERROR Figure 24
23 of 32
DS2181A
CRC4 SUB-MULTIFRAME 2 ERRORED Figure 25
FRAME ALIGNMENT WORD ERRORED Figure 26
CRC4 SUB-MULTIFRAME 1 ERRORED Figure 27
NOTES FOR FIGURES 23 THROUGH 27:
1. CAS multiframe alignment word received in error; RFER will transition high at first error occurrence
and remain high as shown.
2. Previous CRC4 sub-multiframe 2 errored.
3. Frame alignment word errored.
4. Previous CRC4 sub-multiframe 1 errored.
24 of 32
DS2181A
RESET
A high-low transition on RST clears all internal registers except the three error counters; a resync is
initiated until RST returns high. RST must be held low on system power-up and when switching to/from
the hardware mode. Following reset, the host processor should update all on-chip registers to establish
desired operating modes.
HARDWARE MODE
An on-chip hardware control mode simplifies preliminary system prototyping and serves applications
which do not require the features of the serial port. Tying SPS low disables the serial port, clears all
internal register locations except those shown below, and redefines pins 14 through 18 as mode control
inputs. The mode control inputs establish device operational characteristics as shown in Table 8. The
hardware mode simplifies device retrofit into existing applications where control interfaces are designed
with discrete logic.
HARDWARE MODE CONTROL Table 8
PIN NUMBER
14
(16)
REGISTER LOCATION
TINR.5
15
(17)
TXR.2
16
(18)
CCR.5/CCR.4
17
(19)
CCR.3/CCR.2
18
(20)
TCR.5/RCR.5
NAME AND DESCRIPTION
TRA - Transmit Remote Alarm
0 = Normal operation
1 = Enable alarm
TDMA - Transmit Distant Multiframe
Alarm
0 = Normal operation
1 = Enable alarm
Data Format
0 = Input and output data AMI coded
1 = Input and output data HDB3 coded
Transmit and Receive CRC4 Multiframe
0 = Disabled
1 = Enabled
Transmit and Receive CAS Multiframe
0 = Enabled
1 = Disabled
NOTE:
1. Pin numbers for PLCC package are listed in parenthesis.
25 of 32
DS2181A
ABSOLUTE MAXIMUM RATINGS*
Voltage on Any Pin Relative to Ground
Operating Temperature
Storage Temperature
Soldering Temperature
-1.0V to +7.0V
0° to 70°C
-55°C to +125°C
260°C for 10 seconds
* This is a stress rating only and functional operation of the device at these or any other conditions above
those indicated in the operation sections of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods of time may affect reliability.
RECOMMENDED DC OPERATING CONDITIONS
PARAMETER
SYMBOL
MIN
Input Logic 1
VIH
Input Logic 0
Supply
MAX
UNITS
2.0
VDD+.3
V
VIL
-0.3
+0.8
V
VDD
4.5
5.5
V
DC ELECTRICAL CHARACTERISTICS
PARAMETER
SYMBOL
MIN
TYP
(0°C to 70°C)
NOTES
(0°C to 70°C; VDD = 5.0V ± 10%)
TYP
MAX
UNITS
NOTES
6
10
mA
1,2
+1.0
µA
3
Supply Current
IDD
Input Leakage
IIL
-1.0
Output Current @ 2.4V
IOH
-1.0
mA
4
Output Current @ .4V
IOL
+4.0
mA
5
Output Leakage
ILO
-1.0
µA
6
NOTES:
1. TCLK = RCLK = 2.048 MHz.
2. Outputs open.
3. 0V < VIN < VDD.
4. All outputs except INT , which is open collector.
5. All outputs.
6. Applies to SDO when tri-stated.
26 of 32
+1.0
DS2181A
SERIAL PORT WRITE AC TIMING DIAGRAM Figure 28
NOTE:
1. Shaded regions indicate “don’t care” states of input data.
SERIAL PORT READ1 AC TIMING Figure 29
NOTE:
1. Serial port write must precede a port read to provide address information.
27 of 32
DS2181A
AC ELECTRICAL CHARACTERISTICS
PARAMETER
SDI to SCLK Setup
SCLK to SDI Hold
SCLK Low Time
SCLK High Time
SCLK Rise and Fall Time
CS to SCLK Setup
SCLK to CS Hold
CS Inactive Time
SLK to SDO Valid
CS to SDO High Z
1,2
SERIAL PORT
(0°C to 70°C; VDD = 5.0V ± 5%)
SYMBOL
MIN
tDC
tCDH
tCL
tCH
tR, tF
tCC
tCCH
tCWH
tCDV
tCDZ
50
50
244
244
TYP
MAX
100
50
50
2.5
200
75
UNITS
NOTES
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
NOTES:
1. Measured at VIH =2.0 V; VIL =.8 V and 10 ns maximum rise and fall time.
2. Output load capacitance = 100 pF.
AC ELECTRICAL CHARACTERISTICS1,2 – TRANSMIT
(0°C to 70°C; VDD = 5.0V ± 5%)
PARAMETER
SYMBOL
MIN
TYP
MAX
TCLK Period
TCLK Pulse Width
TCLK Raise & Fall Time
TSER, TSD, TIND and TXD
Setup to TCLK Falling
TSER, TSD, TIND and TXD
Hold to TCLK Falling
TFSYNC, TMSYNC Setup to
TCLK Falling
TFSYNC, TMSYNC Hold to
TCLK Falling
Propagation Delay TCLK to
TCHCLK, TSTS, TMO, TAF
tP
tWL, tWH
tW, tR
tSTD
50
ns
ns
ns
ns
tHTD
50
ns
tSTS
75
ns
tHTS
50
ns
488
244
20
tPTS
75
NOTES:
1. Measured at VIH = 2.0V; VIL = .8V and 10 ns maximum rise and fall time.
2. Output load capacitance = 100 pF.
28 of 32
UNITS
ns
NOTES
DS2181A
AC ELECTRICAL CHARACTERISTICS
PARAMETER
SYMBOL
Propagation Delay RCLK to
RMSYNC, RFSYNC, RSTS,
RCHCLK, RAF
1,2
– RECEIVE
(0°C to 70°C; VDD = 5.0V ± 5%)
MAX
UNITS
tPRS
75
ns
Propagation Delay RCLK to
RSER, RSD
tPRD
75
ns
Transition Time All Outputs
tTTR
20
ns
RCLK Period
MIN
TYP
tP
488
ns
tWL, tWH
244
ns
RCLK Rise and Fall Times
tR, tF
20
ns
RPOS, RNEG Setup to RCLK
Falling
tSRD
50
ns
RPOS, RNEG Hold to RCLK
Falling
tHRD
50
ns
Propagation Delay RCLK to
RLOS, RRA, RBA, RFER,
RDMA, RCL
tPRA
Minimum RST Pulse Width
tRST
RCLK Pulse Width
75
1
NOTES
ns
µs
NOTES:
1. Measured at VIH = 2.0V; VIL = .8V and 10 ns maximum rise and fall times.
2. Output load capacitance = 100 pF.
CAPACITANCE
PARAMETER
Input Capacitance
Output Capacitance
(tA =25°C)
SYMBOL
MIN
MAX
UNITS
CIN
5
pF
COUT
7
pF
29 of 32
TYP
NOTES
DS2181A
TRANSMIT AC TIMING DIAGRAM Figure 30
RECEIVE AC TIMING DIAGRAM Figure 31
30 of 32
DS2181A
DS2181A CEPT TRANSCEIVER (600-MIL DIP) 40-PIN
DIM
A
B
C
D
E
F
G
H
J
K
N
MIN
2.050
0.530
0.140
0.600
0.015
0.120
0.090
0.625
0.008
0.015
INCHES
MAX
2.075
0.550
0.160
0.625
0.040
0.145
0.110
0.675
0.012
0.022
40
31 of 32
DS2181A
DS2181AQ CEPT TRANSCEIVER (PLCC)
DIM
A
A1
A2
B
B1
C
CH1
D
D1
D2
E
E1
E2
e1
N
INCHES
MIN
MAX
0.165
0.180
0.090
0.120
0.020
0.026
0.033
0.013
0.021
0.009
0.012
0.042
0.048
0.685
0.695
0.650
0.656
0.590
0.630
0.685
0.695
0.650
0.656
0.590
0.630
0.050 BSC
44
-
32 of 32