Zarlink MT8930CP Subscriber network interface circuit Datasheet

CMOS ST-BUS FAMILY MT8930C
Subscriber Network Interface Circuit
Data Sheet
Features
ISSUE 3
•
ETS 300-012, CCITT I.430 and ANSI T1.605
S/T interface
•
Full-duplex 2B+D, 192 kbit/s transmission
•
Link activation/deactivation
•
D-channel access contention resolution
•
Point-to-point, point-to-multipoint and star
configurations
•
Master (NT)/Slave (TE) modes of operation
•
Exceeds loop length requirements
•
Complete loopback testing capabilities
•
On chip HDLC D-channel protocoller
•
8 bit Motorola/Intel microprocessor interface
•
Controllerless or microprocessor-controlled
operation
•
Zarlink ST-BUS interface
•
Low power CMOS technology
•
Single 5 volt power supply
ISDN NT1
•
ISDN S or T interface
ISDN Terminal Adaptor (TA)
•
Digital sets (TE1) - 4 wire ISDN interface
•
Digital PABXs, Digital Line Cards (NT2)
DSTo
Description
The MT8930C Subscriber Network Interface Circuit
(SNIC) implements the ETSI ETS 300-012, CCITT
I.430 and ANSI T1.605 Recommendations for the
ISDN S and T reference points. Providing point-topoint and point-to-multipoint digital transmission, the
SNIC may be used at either end of the subscriber
line (NT or TE).
The MT8930C is fabricated in Zarlink’s CMOS
process.
•
DSTi
Ordering Information
MT8930CE
28 Pin Plastic DIP
MT8930CP
44 Pin PLCC
-40°C to +85°C
An HDLC D-channel protocoller is included and
controlled through a Motorola/Intel microprocessor
port. A controllerless mode allows the SNIC to
operate without a microprocessor.
Applications
•
November 1997
D-channel Priority
Mechanism
ST-BUS
Interface
LTx
S-Bus
Link
Interface
VBias
LRx
F0od
PLL
C4b
HDLC
Transceiver
Timing
and
Control
F0b
STAR/Rsto
Link
Activation
Controller
VDD
CK/NT
Cmode
VSS
Microprocessor Interface
Rsti
HALF
AD0-7
R/W/WR,
AFT/PRI
DS/RD,
DinB
AS/ALE,
P/SC
CS,
DReq
IRQ/NDA,
DCack
Figure 1 - Functional Block Diagram
1
MT8930C
28
27
26
25
24
23
22
21
20
19
18
17
16
15
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28 PIN PDIP
VDD
VBias
LTx
LRx
STAR/Rsto
Rsti
AD7, DR
AD6, AR
AD5, M/S
AD4, MCH
AD3, MFR
AD2, SYNC/BA
AD1, IS1
AD0, IS0
F0od
DSTi
DSTo
NC
NC
NC
Cmode
CK/NT
NC
R/W/WR, AFT/PRI
DS/RD, DinB
6 5 4 3 2 1 44 43 42 41 40
7
39
8
38
9
37
10
36
11
35
12
34
13
33
14
32
15
31
16
30
29
17
18 19 20 21 22 23 24 25 26 27 28
NC
STAR/Rsto
Rsti
NC
AD7, DR
AD6, AR
NC
AD5, M/S
AD4, MCH
AD3, MFR
NC
NC
AS/ALE, P/SC
CS, DReq
IRQ/NDA, DCack
VSS
NC
AD0, IS0
AD1, IS1
AD2, SYNC/BA
NC
NC
HALF
C4b
F0b
F0od
DSTi
DSTo
Cmode
CK/NT
R/W/WR, AFT/PRI
DS/RD, DinB
AS/ALE, P/SC
CS, DReq
IRQ/NDA, DCack
VSS
NC
NC
F0b
C4b
HALF
NC
VDD
VBias
LTx
NC
LRx
Data Sheet
44 PIN PLCC
Figure 2 - Pin Connections
Pin Description
Pin #
Name
Description
2
HALF
HALF Input/Output: this is an input in NT mode and an output in TE mode identifying
which half of the S-interface frame is currently being written/read over the ST-BUS
(HALF = 0 sampled on the falling edge of C4b within the frame pulse low window,
identifies the information to be transmitted/received in the first half of the S-Bus frame
while HALF = 1 identifies the information to be transmitted/received into the second half
of the S-Bus frame). Tying this pin to VSS or VDD in NT mode will allow the device to
free run. This signal can also be accessed from the ST-BUS C-channel.
2
3
C4b
4.096 MHz Clock: a 4.096 MHz ST-BUS Data Clock input in NT mode.
In TE mode, a 4.096 MHz output clock phase-locked to the line data signal.
3
4
F0b
Frame Pulse: an active low frame pulse input indicating the beginning of active STBUS channel times in NT mode. Frame pulse output in TE mode.
4
7
F0od
Delayed Frame Pulse Output: an active low delayed frame pulse output indicating
the end of active ST-BUS channels for this device. Can be used to daisy chain
to other ST-BUS devices to share an ST-BUS stream.
5
8
DSTi
Data ST-BUS Input: a 2048 kbit/s serial PCM/data ST-BUS input with D, C, B1, and B2
channels assigned to the first four timeslots. These channels contain data to be
transmitted on the line and chip control information.
6
9
DSTo
Data ST-BUS Output: a 2048 kbit/s serial PCM/data ST-BUS output with D, C, B1 and
B2 channels assigned to the first four timeslots respectively. The remaining timeslots
are placed into high impedance. These channels contain data received from the line
and chip status information.
7
13
Cmode
Controller Mode Select Input: when high, microprocessor control is selected. When
low the controllerless mode is enabled and the microport pins are redefined as control
inputs and status outputs.
8
14
CK/NT
TE Clock/Network Termination Mode Select Input. For TE mode, this pin must be
tied to VSS or to a 4.096 MHz clock (a clock is required for standard ISDN TE
applications). For NT mode, this pin must be tied to VDD. Refer to “ST-BUS Interface”
section for further explanation. A pull-up resistor is needed when driven by a TTL
device.
DIP
PLCC
1
2
MT8930C
Data Sheet
Pin Description (continued)
Pin #
DIP
PLCC
9
16
10
17
Name
R/W/WR Read/Write or Write Input (Cmode = 1): defines the data bus transfer as a read (R/
W=1) or a write (R/W=0) in Motorola bus mode. Redefined to WR in Intel bus mode.
AFT/PRI Adaptive-Fixed Timing/Priority Select Input (Cmode=0): in NT mode, causes the
PLL and Rx filters and peak detectors to be disabled in favour of fixed timing and fixed
thresholds for short passive bus operation (0=fixed, 1=adaptive). In TE mode, this is the
Priority input. High priority (PRI=1) is normally reserved for signalling.
DS/RD
DinB
11
19
AS/ALE
P/SC
12
20
CS
DReq
IC
13
21
IRQ
NDA
DCack
IC
14
22
VSS
15- 24-26
22 30-32
34-35
AD0-7
1516
IS0-IS1
2425
Description
Data Strobe/Read Input (Cmode = 1): active high input indicates to the SNIC that
valid data is on the bus during a write operation or that the SNIC must output data
during a read operation in Motorola bus mode. Redefined to RD in Intel bus mode.
D-Channel in B1 Timeslot Input (Cmode = 0): active high input that causes all
eight ST-BUS D-channel bits, instead of the usual two bits, to be routed to and
from the S-interface B1 timeslot. When active, marks are transmitted in the
S-interface D-channel.
Address Strobe/Address Latch Enable Input (Cmode = 1): in Motorola bus mode
the falling edge is used to strobe the address into the SNIC during microprocessor
access. Redefined to ALE in Intel bus mode.
Parallel/Serial Control Input (Cmode = 0): determines if the serial C-channel
(P/SC=0) or microport pins (P/SC=1) are the source of chip control when controllerless
mode is selected. If the ST-BUS is chosen as the source, the dedicated Control input
pins are ignored but the status output pins remain valid.
Chip Select Input (Cmode=1): active low input used to select the SNIC for
microprocessor access.
D-Channel Request Input (Cmode = 0): an active high input that in TE mode only
causes the SNIC to transmit a “01111110” flag immediately if the D-channel is free, or
wait until it becomes available and then transmit the flag. The DCack signals the
successful acquisition of the D-channel. If DReq is tied low, continuous ones are
transmitted in the S-Bus D-channel.
Internal Connection (Cmode = 0): tie to VSS for normal operation in NT mode only.
Interrupt Request (Open Drain Output) (Cmode = 1): an output indicating an
unmasked HDLC interrupt. The interrupt remains active until the microprocessor clears
it by reading the HDLC Interrupt Status Register. This interrupt source is enabled with
B2=0 of Master Control Register.
New Data Available (Open Drain Output) (Cmode = 1): an active low output signal
indicating availability of new data from the S-Bus. This signal is selected with B2=1 of
Master Control Register.
D-Channel Acknowledge (Open Drain Output) (Cmode = 0): in TE mode only
indicates that the SNIC has gained access to the D-channel in response to a DReq and
has transmitted the first zero of an opening flag. The user should immediately begin
transmitting the rest of the packet over the ST-BUS D-channel. If this signal goes high
in the middle of transmission, the TE has lost the bus and must regain access of the Dchannel before retransmitting the packet.
Internal Connection (Open Drain Output) (C-mode=0). This pin is not used in NT
mode and should be left disconnected.
This pin must be tied to VDD with a 10kΩ resistor.
Ground.
Bidirectional Address/Data Bus (Cmode = 1): electrically and logically compatible to
either Intel or Motorola micro-bus specifications. If DS/RD is low on the rising edge of
AS/ALE then the chip operates to Motorola specs. If DS/RD is high on the rising edge
of AS/ALE Intel mode is selected. Taking Rsti low sets Motorola mode.
Internal State Outputs (Cmode =0): Binary encoded state number outputs.
IS0
0
0
1
1
IS1
0
1
0
1
NT Mode
deactivated
pending deactivation
pending activation
activated
TE Mode
deactivated
synchronized
activation request
activated
3
MT8930C
Data Sheet
Pin Description (continued)
Pin #
Name
Description
DIP
PLCC
17
26
18
30
MFR
Multiframe Input/Output (Cmode=0): multiframe input in NT mode or output in TE
mode. Setting this pin to one in NT mode when HALF = 1, forces the FA, N pair to 1, 0
respectively. This pin going high in TE mode indicates that FA= 1 & N= 0 has been
received. This signal is updated on the rising edge of the HALF signal.
19
31
MCH
Maintenance Channel (Q-channel) Input/Output (Cmode=0): an output in NT mode
which is valid only in the frame following the transmission of MFR. In TE mode, this is
the maintenance channel (Q-channel) input which is transmitted in the FA and L bits
following the reception of the multiframe signal. This input is sampled on the falling
edge of the HALF signal.
20
32
M/S
M/S Input/Output (Cmode=0): M/S bit input in NT mode or M/S bit output in TE mode.
M is read or written when HALF=1 while S is read or written when HALF=0.
21
34
AR
Activate Request Input (Cmode = 0): asserting AR with DR = 0 will initiate the
appropriate S-interface activation sequence coded in the NT or TE activation/
deactivation controller.
22
35
DR
Deactivate Request Input (Cmode = 0): asserting DR high will initiate the appropriate
S-interface deactivation sequence coded in the NT or TE activation/ deactivation
controller.
23
37
Rsti
Reset Input: Schmitt trigger reset input. If ’0’, sets all control registers to the default
conditions, resets activation state machines to the deactivated state, resets HDLC,
clears the HDLC FIFO‘s. Sets the microport to Motorola bus mode.
24
38
25
40
LRx
Receive Line Signal Input: this is a high impedance input for the pseudoternary line
signal to be connected to the line through a 2:1 ratio transformer. See Figures 20 and
21. A DC bias level on this input equal to VBias must be maintained.
26
42
LTx
Transmit Line Signal Output: this is a current source output designed to drive a
nominal 50 ohm line through a 2:1 ratio transformer. See Figures 20 and 21.
27
43
VBias
Bias Voltage: analog ground for Tx and Rx transformers. This pin must be decoupled
to VDD through a 10µF capacitor with good high frequency characteristics (i.e.,
tantalum).
28
44
VDD
Power Supply Input.
1,5-6,1012,15,18,
23,27-29,
33, 36,
39, 41
NC
No Connection.
4
SYNC/BA Synchronization/Bus Activity Output (Cmode = 0): output indicating synchronization
to incoming RX frames when activation request is asserted and the deactivation request
is ’0’ (AR = 1 and DR = 0). Synchronization is declared once three successive frames
conforming to the 14-bit bipolar violation criteria have been detected. If part is
deactivated or activation request is ’0’ (AR = 0 or DR = 1), this pin indicates the
presence of bus activity.
STAR/Rsto Star/Reset (Open Drain Output): 192kbit/s Rx data output fixed relative to the ST-BUS
timebase. A group of NTs, in fixed timing mode, can be wire or’ed together to create a
Star configuration. Active low reset output in TE mode indicating 128 consecutive
marks have been received. Can be connected directly to Rsti to allow NT to reset all
TEs on the bus. This pin must be tied to VDD with a 10 kΩ resistor.
MT8930C
Data Sheet
Functional Description
allows implementation of maintenance functions and
monitoring of the device and the subscriber loop.
The MT8930C Subscriber Network Interface Circuit
(SNIC) is a multifunction transceiver providing a
complete interface to the S/T Reference Point as
specified in ETS 300-012, CCITT Recommendation
I.430 and ANSI T1.605. Implementing both
point-to-point and point-to-multipoint voice/data
transmission, the SNIC may be used at either end of
the digital subscriber loop. A programmable digital
interface allows the MT8930C to be configured as a
Network Termination (NT) or as a Terminal
Equipment (TE) device.
The SNIC supports 192 kbit/s (2B+D + overhead) full
duplex data transmission on a 4-wire balanced
transmission line. Transmission capability for both B
and D channels, as well as related timing and
synchronization functions, are provided on chip. The
signalling capability and procedures necessary to
enable customer terminals (TEs) to be activated and
deactivated, form part of the MT8930C’s
functionality. The SNIC handles D-channel resource
allocation and prioritization for access contention
resolution and signalling requirements in passive bus
line configurations. Control and status information
28
27
26
25
24
23
22
21
20
19
18
17
16
15
1
2
3
4
5
6
7
8
9
10
11
12
13
14
A block diagram of the MT8930C is shown in Figure
1. The SNIC has three interface ports: a 4-wire
CCITT compatible S/T interface (subscriber loop
interface), a 2048 kbit/s ST-BUS serial port, and a
general purpose parallel microprocessor port. This
8-bit parallel port is compatible with both Motorola or
CONTROLLER MODE
NT MODE
HALF
C4bi
F0bi
F0od
DSTi
DSTo
Cmode
NT
R/W/WR
DS/RD
AS/ALE
CS
IRQ, NDA
VSS
An HDLC transceiver is included on the SNIC for link
access protocol handling via the D-channel.
Depacketized data is passed to and from the
transceiver via the microprocessor port. Two 19 byte
deep FIFOs, one for transmit and one for receive,
are provided to buffer the data. The HDLC block can
be set up to transmit or receive to/from either the
S-interface port or the ST-BUS port. Further, the
transmit destination and receive source can be
independently selected, e.g., transmit to S-interface
while receiving from ST-BUS. The transmit and
receive paths can be separately enabled or disabled.
Both, one and two byte address recognition is
supported by the SNIC. A transparent mode allows
data to be passed directly to the D channel without
being packetized.
VDD
VBias
LTx
LRx
STAR
Rsti
AD7
AD6
AD5
AD4
AD3
AD2
AD1
AD0
HALF
C4bo
F0bo
F0od
DSTi
DSTo
Cmode
CK
R/W/WR
DS/RD
AS/ALE
CS
IRQ, NDA
VSS
TE MODE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
VDD
VBias
LTx
LRx
Rsto
Rsti
AD7
AD6
AD5
AD4
AD3
AD2
AD1
AD0
28
27
26
25
24
23
22
21
20
19
18
17
16
15
VDD
VBias
LTx
LRx
Rsto
Rsti
DR
AR
M/So
MCHi
MFRo
SYNC/BA
IS1
IS0
CONTROLLERLESS MODE
NT MODE
HALF
C4bi
F0bi
F0od
DSTi
DSTo
Cmode
NT
AFT
DinB
P/SC
IC
IC
VSS
1
2
3
4
5
6
7
8
9
10
11
12
13
14
TE MODE
28
27
26
25
24
23
22
21
20
19
18
17
16
15
VDD
VBias
LTx
LRx
STAR
Rsti
DR
AR
M/Si
MCHo
MFRi
SYNC/BA
IS1
IS0
HALF
C4bo
F0bo
F0od
DSTi
DSTo
Cmode
CK
PRI
DinB
P/SC
DReq
DCack
VSS
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Figure 3 - SNIC Pin Connections in Various Modes
5
Channel 3 (B2)
B2
B2
B2
Intel microprocessor bus signals and timing. The
SNIC also has provisions for a controllerless mode
(Cmode=0), where the microprocessor port is
redefined to allow access to the control/status
registers via external hardware.
Don’t care
Channel 2 (B1)
B1
B1
Channel 1 (C)
C3
C4
C5
C6
Channel 0 (D)
F0od
Only valid with 64 kbit/s D-channel
D6
D5
D4
D3
D2
D1
D0
DSTo
Figure 4 - ST-BUS Channel Assignment
6
The three major blocks of the MT8930C, consisting
of the system serial interface (ST-BUS), HDLC
transceiver, and the digital subscriber loop interface
(S-interface) are interconnected by high speed data
busses.
Data sent to and received from the
S-interface port (B1, B2 and D channels) can be
accessed from either the parallel microprocessor
port or the serial ST-BUS port. This is also true for
SNIC control and status information (C-channel).
Depacketized D-channel information to and from the
HDLC section can only be accessed through the
parallel microprocessor port.
S-Bus Interface
The S-Bus is a four wire, full duplex, time division
multiplexed transmission facility which exchanges
information at 192 kbit/s rate including two 64 kbit/s
PCM voice or data channels, a 16 kbit/s signalling
channel and 48 kbit/s for synchronization and
overhead. The relative position of these channels
with respect to the ST-BUS is shown in Figures 4
and 5.
The SNIC makes use of the first four channels on the
ST-BUS to transmit and receive control/status and
data to and from the S-interface port. These are the
B, D and C-channels (see Figure 4).
The B1 and B2 channels each have a bandwidth of
64 kbit/s and are used to carry PCM voice or data
across the network.
D7
C7
Output in high impedance state
C0
C2
C1
B1
B1
B1
B1
B1
B1
B2
B2
B2
B2
B2
B2
B2
B2
B2
B2
B2
B1
B1
B1
B1
B1
B1
B1
B1
C0
C1
C2
C3
C4
C5
C6
C7
D7
D6
D5
D4
D3
D2
D1
D0
DSTi
F0b
Data Sheet
B2
B2
MT8930C
The D-channel is primarily intended to carry
signalling information for circuit switching through
the ISDN network. The SNIC provides the capability
of having a 16 kbit/s or full 64 kbit/s D-channel by
allocating the B1-channel timeslot to the D-channel.
Access to the depacketized D-channel is only
granted through the parallel microprocessor port.
The C-channel provides a means for the system to
control and monitor the functionality of the SNIC.
This control/status channel is accessed by the
system through the ST-BUS or microprocessor port.
The C-channel provides access to two registers
which provide complete control over the state
activation
machine,
the
D-channel
priority
mechanism as well as the various maintenance
functions. A detailed description of these registers is
discussed in the microprocessor port interface.
HALF
Input
DSTo
F0b
NDA
HALF
Output
DSTi
F0b
B2 L
HALF
Output
DSTo
F0b
NDA
HALF
Input
DSTi
F0b
D1 L
L
F = Framing bit
L = DC balancing bit
D = Bit within D-channel
E = D-echo channel bit
R
C
V
N
T
X
M
T
T
E
TE to NT
R
C
V
T
E
X
M
T
N
T
NT to TE
F
F
L
D0 L
Fa L
B2 B2 B2 B2 B2 B2 B2 B2 L
D1 L
D0 S
A = Activation bit
M = Multiframing bit
S = S-channel bit
62.5 µs
B1 B1 B1 B1 B1 B1 B1 B1 L
B1 B1 B1 B1 B1 B1 B1 B1 E
Figure 5 - S-Bus Frame Structure and Functional Timing
Fa & N (NT to TE) = Auxiliary framing bits
Fa (TE to NT) = Auxiliary framing bit or Q-channel bit
B1 = Bit within B1-channel
B2 = Bit within B2-channel
62.5 µs
B1 B1 B1 B1 B1 B1 B1 B1 L
62.5 µs
B1 B1 B1 B1 B1 B1 B1 B1 E D0 A Fa N B2 B2 B2 B2 B2 B2 B2 B2 E D1 M
D0 L
D1 L
L
D1 L
F
F
L
B1 B1 B1
B1 B1 B1 B1 B1
Note: Shaded areas reveal data mapping
B2 B2 B2 B2 B2 B2 B2 B2 L
62.5 µs
B2 B2 B2 B2 B2 B2 B2 B2 E
Data Sheet
MT8930C
7
MT8930C
Data Sheet
Line Code
The line code used on the S-interface is a Pseudo
ternary code with 100% pulse width as seen in
Figure 6 below. Binary zeros are represented as
marks on the line and successive marks will
alternate in polarity.
BINARY
VALUE
0
1
0
0
0
1
0
0
1
1
LINE
SIGNAL
Violation
Figure 6 - Alternate Zero Inversion Line Code
A mark which does not adhere to the alternating
polarity is known as a bipolar violation.
Framing
The valid frame structure transmitted by the NT and
TE contains the following (refer Fig. 5):
NT to TE:
- Framing bit (F)
- B1 and B2 channels (B1,B2)
- DC balancing bits (L)
- D-channel bits (D0, D1)
- Auxiliary framing and N bit (Fa, N), N=Fa
- Activation bit (A)
- D-echo channel bits (E)
- Multiframing bit (M)
- S-channel bit
TE to NT:
- Framing bit (F)
- B1 and B2 channels (B1, B2)
- DC balancing bits (L)
- D-channel bits (D0, D1)
- Auxiliary framing bit (Fa) or Q-channel bit
The framing mechanism on the S-interface makes
use of line code violations to identify frame
boundaries. The F-bit violates the alternating
line code sequence to allow for quick identification of
the frame boundaries. To secure the frame
alignment, the next mark following the frame
balancing bit (L) will also produce a line code
violation. If the data following the balancing bit is all
binary ones, the zero in the auxiliary framing bit (Fa)
or N-bit (for the direction NT to TE) will provide
successive violations to ensure that the 14 bit
8
criterion (13 bit criterion in the direction TE to NT)
specified in Recommendations I.430 and T1.605 is
satisfied. If the B1-channel is not all binary ones, the
first zero following the L-bit will violate the line code
sequence, thus allowing subsequent marks to
alternate without bipolar violations.
The Fa and N bits can also be used to identify a
multiframe structure (when this is done, the 14 bit
criterion may not be met). This multiframe structure
will make provisions for a low speed signalling
channel to be used in the TE to NT direction
(Q-channel). It will consist of a five frame multiframe
which can be identified by the binary inversion of the
Fa and N-bit on the first frame and consequently on
every fifth frame of the multiframe. Upon detection
of the multiframe signal, the TE will replace the next
Fa-bit to be transmitted with the Q-bit.
The DC balancing bits (L) are used to remove any
DC content from the line. The balancing bit will be a
mark if the number of preceding marks up to the
previous balancing bit is odd.
If the number of
marks is even, the L-bit will be a space.
The A-bit is used by the NT during line activation
procedures (refer to state activation diagrams). The
state of the A-bit will advise the TE if the NT has
achieved synchronization.
The E-bit is the D-echo channel. The NT will reflect
the binary value of the received D-channel into the
E-bits.
This is used to establish the access
contention resolution in a point-to-multipoint
configuration. This is described in more detail in the
section of the D-channel priority mechanism.
The M-bit is a second level of multiframing which is
used for structuring the Q-bits. The frame with Mbit=1 identifies frame #1 in the twenty frame
multiframe. The Q-channel is then received as
shown in Table 1. All synchronization with the
multiframes must be performed externally.
FRAME #
Q-Bit
1
Q1
M-Bit
1
6
11
16
Q2
Q3
Q4
0
0
0
Table 1. Q-channel Allocation
Bit Order
When using the B-channels for PCM voice, the first
bit to be transmitted on the S-Bus should be the sign
bit.
This complies with the existing telecom
standards which transmit PCM voice as most
significant bit first. However, if the B-channels are to
MT8930C
Data Sheet
carry data, the bit ordering must be reversed to
comply with the existing datacom standards (i.e.,
least significant bit first).
These contradicting standards place a restriction on
all information input and output through the serial
and parallel ports. Information transferred through
the serial ports, will maintain the integrity of the bit
order. Data sent to either serial port from the parallel
port, will transmit the least significant bit first.
Therefore, a PCM byte input through the
microprocessor port must be reordered to have the
sign bit as the least significant bit.
When the microprocessor reads D, B1 or B2 channel
data of either ST-BUS or S-bus serial port, the least
significant bit read is the first bit received on that
particular channel of either serial port.
The D-channel received on the serial ST-BUS ports
must be ordered with the least significant bit first as
shown in Figure 4.
This also applies to the
D-channel directed to the ST-BUS from the
microprocessor port.
The C-channel bit mapping from the parallel port to
the ST-BUS is organized such that the most
significant bit is transmitted or received first.
State Activation
The state activation controller activates or
deactivates the SNIC in response to line activity or
external command. The controller is completely
hardware driven and need not be initialized by the
microprocessor. The state diagram for initialization
is shown in Figure 7.
The protocol used by the state activation controller is
defined as follows:
1)
2)
3)
4)
5)
In the deactivated state, neither the NT nor
TE assert a signal on the line (Info0).
If the TE wants to initiate activation, it must
begin transmitting a continuous signal
consisting of a positive zero, a negative zero
followed by six ones (Info1).
Once the NT has detected Info1, it begins to
transmit Info2 which consists of an S-Bus
frame with zeros in the B and D-channel and
the activation bit (A-bit) set to zero.
As soon as the TE synchronizes to Info2, it
responds with a valid S-Bus frame with data
in the B1, B2 and D-channel (Info3).
The NT will then transmit a valid frame with
data in the B1, B2 and D-channel. It will also
set the activation bit (A) to binary one once
synchronization to Info3 is achieved.
If the NT wishes to initiate the activation, steps 2 and
3 are ignored and the NT starts sending Info2. To
initiate a deactivation, either end begins to send
Info0 (Idle line).
D-channel Priority Mechanism
The SNIC contains a hardware priority mechanism
for D-channel contention resolution.
All TEs
connected in a point-to-multipoint configuration are
allocated the D-channel using a systematic
approach.
Allocation of the D-channel is
accomplished by monitoring the D-echo channel
(E-bit) and incrementing the D-channel priority
counter with every consecutive one echoed back in
the E bit. Any zero found on the D-echo channel will
reset the priority counter.
There are two classes of priority within the SNIC,
one user accessible and the other being strictly
internal. The user accessible priority selects the
class of operation and has precedence over the
internal priority. The latter (internal priority), will
select the level of priority within each class (i.e., the
internal priority is a subsection of the user accessible
priority). User accessible priority selects the terminal
count as 8/9 or 10/11 consecutive ones on the E-bit
(8 being high priority while 10 being low priority).
The internal priority selects the terminal between 8
or 9 for high class and 10 or 11 for low class. The
first terminal equipment to attain the E-bit priority
count will immediately take control of the D-channel
by sending the opening flag. If more than one
terminal has the same priority, all but one of them will
eventually detect a collision. The TEs that detect a
collision will immediately stop trans-mitting on the Dchannel, generate an interrupt through the Dcoll bit,
reset the DCack bit on the next frame pulse, and
restart the counting process. The remainder of the
packet in the Tx FIFO is ignored.
After successfully completing a transmission, the
internal priority level is reduced from high to low.
The internal priority will only be increased once the
terminal count for the respective level of priority has
been achieved (e.g., if TE has high priority internally
and externally, it must count 8 consecutive ones in
the D-echo channel. Once this is achieved and
successful transmission has been completed, the
internal priority is reduced to a lower level (i.e., count
= 9). This terminal will not return to the high internal
priority until 9 consecutive ones have been
monitored on the D-echo channel).
9
MT8930C
Data Sheet
Signals from NT to TE
Info0
No Signal
Info2
Valid frame structure with
all B, D, D-echo and A bits
set to ‘0’
Info4
Where: BA(2) = Bus Activity
DR = Deactivation Request
AR = Activation Request
Sync(2) = Frame Sync Signal
A = Activation bit
Time out = 32 ms Timer Signal
Signals from TE to NT
Info0
Info1
No Signal
Continuous Signal of +‘0’, -‘0’
and six ‘1’s(1)
Note 1: signal is not timebase locked to NT.
Info3
Valid frame with data in B,
D, D-echo channels. Bit A is
set to 1.
TE State Activation Diagram
Note 2: Sync/BA bit of the Status Register
is configured as Sync bit when
AR = 1 and DR = 0, or as BA bit
when AR = 0 or DR = 1. A change in
the state of the AR and/or DR bits
will cause a change in the function
of the Sync/BA bit in the following
ST-BUS frame.
Valid frame with data in B & D
Bits
Activation Request
send Info1 if BA = 0
send Info0 if BA = 1
DR = 1
Sync = 1
AR = 1
BA = 0
Synchronized
send Info3 if Sync = 1
send Info0 if Sync = 0
Sync = 1
Deactivated
send Info0
DR = 1
A=1&
Sync = 1
DR = 1
BA = 0
Sync = 0
A=0
Activated
send Info3
NT State Activation Diagram
BA = 1
Deactivated
send Info0
AR = 1
Time out
BA =0
DR = 1
Pending
Activation
send Info2
AR = 1
Pending
Deactivation
Send Info0
Sync = 1
DR = 1
Sync = 0
Activated
send Info4
Figure 7 - Link Activation Protocol, State Diagram
For an NT SNIC in fixed timing mode, the VCO and
Line Wiring Configuration
Rx filters/peak detectors are disabled and the
threshold voltage is fixed. However, for a TE SNIC
The MT8930C can interface to any of the three
or an NT SNIC (in adaptive timing mode), the VCO
wiring configurations which are specified by CCITT
and Rx filters/peak detectors are enabled. In this
Recommendation I.430 and ANSI T1.605 (refer to
manner, the device can compensate for variable
Figs. 8 to 10). These consist of a point-to-point or
round trip delays and line attenuation using a
one of the two point-to-multipoint configurations (i.e.,
threshold voltage set to a fixed percentage of the
short passive bus or the extended passive bus). The
pulse peak amplitude.
selection of line configurations is performed using
the timing bit (B4 of NT Mode Control Register).
Another operation can be implemented using the
SNIC in the star configuration as shown in Figure 14.
For the short passive bus, TE devices are connected
This mode allows multiple NTs, with physically
at random points along the cable. However, for the
independent S-Busses, to share a common input
extended passive bus all connection points are
source and transfer information down the S-Bus to
grouped at the far end of the cable from the NT.
10
MT8930C
Data Sheet
0 - 1 Km
T
R
T
R
NT
TE
NT is operating in adaptive timing
TR is the line termination resistor = 100 Ω
Figure 8 - Point-to-Point Configuration
100 m for 75 Ω
impedance cable and 200 m for 150 Ω
impedance cable
100 - 200 m
NT
T
R
T
0 - 10 m R
TE
TE
TE
TE
TE
TE
TE
TE
NT is operating in fixed timing
TR is the line termination resistor = 100 Ω
Fiure 9 - Short Passive Bus Configuration, up to 8 TEs can be supported
0-500 m
NT
T
R
0-50 m
T
R
0 - 10 m
TE
TE
TE
TE
TE
TE
TE
TE
NT is operating in adaptive timing
TR is the line termination resistor = 100 Ω
Figure 10 - Extended Passive Bus Configuration, up to 8 TEs can be supported
all TEs . All NT devices connected into the star will
receive the information transmitted by all TEs on all
branches of the star, exactly as if they were on the
same physical S-Bus.
All NTs in the star
configuration must be operating in fixed timing mode.
Refer to the description of the star configuration in
the ST-BUS section.
The SNIC has one last mode of operation called the
NT slave mode. This has the effect of operating the
SNIC in network termination mode (CK/NT pin = 1)
but having the frame structure and registers
description defined by the TE mode. This can be
used where multiple subscriber loops must carry a
fixed phase relation between each line. A typical
situation is when the system is trying to synchronize
two nodes of a synchronous network. This allows
multiple TEs to share a common ST-BUS timebase.
The synchronization of the loops is established by
using the clock signals produced by a local TE as an
input timing source to the NT slave.
Adaptive Timing Operation
On power-up or after a reset, the SNIC in NT mode is
set to operate in fixed timing. To switch to adaptive
timing, the user should:
1) set the DR bit to 1
2) set the Timing bit to 1 in the C-channel
Control Register
3) wait for 100 ms period
4) proceed in using the AR and DR bits as
desired
Switching from adaptive timing mode is completed
by resetting the Timing bit.
11
MT8930C
Data Sheet
125 µs
Channel
0
Channel
1
Channel
2
Bit 7
Bit 6
• • •
Bit 5
Channel
30
Bit 4
Bit 3
Bit 2
Channel
31
Bit 1
Channel
0
Bit 0
(8/2048) ms
Figure 11 - ST-BUS Stream Format
F0b
C4b
ST-BUS
BIT CELLS
Channel 31
Bit 0
Channel 0
Bit 7
Channel 0
Bit 6
Channel 0
Bit 5
Channel 0
Bit 4
Figure 12 - Clock & Frame Alignment for ST-BUS Streams
ST-BUS Interface
The ST-BUS is a synchronous time division
multiplexed serial bussing scheme with data streams
operating at 2048 kbit/s configured as 32, 64 kbit/s
channels (refer to Fig. 11). Synchronization of the
data transfer is provided from a frame pulse which
identifies the frame boundaries and repeats at an 8
kHz rate. Figure 4 shows how the frame pulse
(F0b) defines the ST-BUS frame boundaries. All
data is clocked into the device on the rising edge of
the 4096 kHz clock (C4b) three quarters of the way
into the bit cell, while data is clocked out on the
falling edge of the 4096 kHz clock at the start of the
bit cell.
All timing signals (i.e. F0b & C4b) are identified as
bidirectional (denoted by the terminating b). The
I/O configuration of these pins is controlled by the
mode of operation (NT or TE). In the NT mode, all
synchronized signals are supplied from an external
source and the SNIC uses this timing while
transferring information to and from the S or
ST-BUS. In the TE mode, an on-board analog
phase-locked loop extracts timing from the received
data on the S-Bus and generates the system
4096 kHz (C4b) and frame pulse (F0b).
The
analog phase-locked loop also maintains proper
phase relation between the timing signals as well as
filtering out jitter which may be present on the
received line port.
12
When the TE mode is selected by tying the CK/NT
pin low, a continuous INFO0 signal on the receiver
will cause the PLL frequency to drift from its nominal
4.096 MHz value (C4b output). Hence, transmitted
INFO1 from the TE will not be at 192 kbps as
required in I.430 and T1.605. However, if the user’s
application requires the transmission of INFO1 at
exactly 192 kbit/s or the presence of an exact 4.096
MHz C4b clock at all times, then a 4.096 MHz clock
should be connected to the CK/NT pin.
This input clock serves to configure the device in TE
mode and to train the PLL in the absence of an
INFO2 or INFO4 signal on the line.
The SNIC uses the first four channels on the
ST-BUS (as shown in Figure 4). To simplify the
distribution of the serial stream, the SNIC
provides a delayed frame pulse (F0od) to eliminate
the need for a channel assignment circuit. This
signal is used to drive subsequent devices in the
daisy chain (refer Figure 13).
In this type of
arrangement, only the first SNIC in the chain will
receive the system frame pulse (F0b) with the
following devices receiving its predecessor’s delayed
output frame pulse (F0od).
The SNIC makes efficient use of its TDM bus
through the Star configuration. It does so by sharing
four common ST-BUS channels to multiple NT
devices.
MT8930C
Data Sheet
ST-BUS Clock
ST-BUS
Stream
Active on
Channels 4 - 7
Active on
Channel 0 - 3
MT8930C
NT
System
Frame Pulse
MT8930C
NT
F0b
F0b
F0od
MT8930C
NT
F0b
F0od
to TE
to TE
Active on
Channels 12 - 15
Active on
Channels 8 - 11
MT8930C
NT
F0b
F0od
F0od
to TE
to TE
Figure 13 - Daisy Chaining the SNIC
VDD
MT8930C
NT
System
Frame Pulse
to TE
STAR
F0b
DSTi
MT8930C
NT
STAR
F0b
DSTi
DSTo
to TE
Output
ST-BUS Stream
Input
ST-BUS Stream
MT8930C
NT
to TE
STAR
F0b
DSTi
MT8930C
NT
STAR
F0b
DSTi
to TE
Figure 14 - NT in Star Configuration
Up to eight SNICs in NT mode with physically
independent S-Busses can be connected in parallel
to realize a star configuration, as shown in Figure 14.
All devices connected into the star will carry the
same input, thus information is sent to all TEs
simultaneously. The 2B+D data received from every
TE is transmitted to all NTs through the STAR pin.
Consequently, all the DSTo streams will carry
identical 2B+D data reflecting what is being
transmitted by the various TEs.
The flow of data in the direction of S-Bus to ST-BUS
is transparent to the SNIC, regardless of the state
machine status. On the other hand, the flow of data
in the direction of ST-BUS to S-Bus becomes
transparent only after the state machine is in the
active state (IS0, IS1=1,1), in case of an NT, or in the
synchronization state (IS0, IS1=1), in case of a TE.
Microprocessor/Control Interface
The parallel port on the SNIC operates as either a
general purpose microprocessor interface or as a
hardwired control port.
In microprocessor control mode (Cmode = 1), the
parallel port is compatible with either Motorola or
Intel multiplexed bus signals and timing.
The
MOTEL
circuit
(MOtorola
and
InTEL
Compatible bus) uses the level of the DS/RD pin
at the rising edge
of AS/ALE to select the
appropriate bus timing. If DS/RD is low at the
rising edge of AS/ALE (refer Fig. 26) then Motorola
bus timing is selected. Conversely, if DS/RD is
high at the rising edge of AS/ALE (refer Figs. 24 &
25), then Intel bus timing is selected. This has the
effect of redefining the microprocessor port
transparently to the user.
In this mode, the user has the option of writing to the
C-channel Control or Diagnostic Register through
the parallel port interface or through the C-channel
on DSTi. Bit 0 of the Master Control Register
provides this option.
The parallel port on the SNIC allows complete
control of the HDLC transceiver and access to all
data, control and status registers. The internal
registers (defined in Table 2) can be accessed
through the microprocessor port only when the
Cmode pin is held high. Reading these registers
allows the microprocessor to monitor incoming data
on the S or ST-BUS without interrupting the normal
data flow.
13
MT8930C
A
S
Y
N
C
S
Y
N
C
A4
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
Address Lines
A3 A2 A1
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
0
0
0
0
0
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
Data Sheet
A0
0
1
0
1
0
1
0
1
0
1
0
0
0
1
0
1
0
1
0
1
Write
Read
Master Control Register
ST-BUS Control Register
HDLC Control Register 1
HDLC Control Register 2
HDLC Interrupt Mask Register
HDLC Tx FIFO
HDLC Address Byte #1 Register
HDLC Address Byte #2 Register
C-channel Control Register
verify
verify
verify
HDLC Status Register
HDLC Interrupt Status Register
HDLC Rx FIFO
verify
verify
Control Register 1
Not Available
DSTo C-channel
S-Bus Tx D-channel
DSTo D-channel
S-Bus Tx B1-channel
DSTo B1-channel
S-Bus Tx B2-channel
DSTo B2-channel
Table 2. SNIC Address Map
Some registers are classified as asynchronous and
others as synchronous. Synchronous registers are
single-buffered and require synchronous access.
Not all the synchronous registers have the same
access times, but all can be accessed synchronously
in the time during which the NDA signal is low
(refer to Fig. 5). Therefore, it is recommended that
the user make use of the NDA signal to access these
registers. Since the synchronous registers use
common circuitry, it is essential that the register be
read before being written.
This sequence is
important as a write cycle will overwrite the last data
received. These parallel accesses must be refreshed
every frame. Asynchronous registers, on the other
hand, can be accessed at any time.
When the Cmode pin is low, controllerless mode is
selected and the parallel port reverts to hardwired
control/status pins. This allows the MT8930C to
function without the need for a controlling
microprocessor. In the controllerless mode, the
parallel bus has direct connection to the relevant
control/status registers (refer to Pin Description).
Discrete logic can be used to drive/sense
the respective pins.
In this mode, pin 11
(P/SC determines whether the microport pins or
the C-channel bits on DSTi stream are the control
source of the device.
If the C-channel is selected
to be the source, P/SC is tied low, then the
microport pins are ignored and the C-channel is
loaded into the C-channel Control Register.
14
C-channel Status Register
Not available
Master Status Register
DSTi C-channel
DSTi D-channel
S-Bus Rx D-channel
DSTi B1-channel
S-Bus Rx B1-channel
DSTi B2-channel
S-Bus Rx B2-channel
The data in TE or NT Mode Status Register,
depending upon the mode selected, is always sent
out on the C-channel of DSTo.
However, in
microprocessor control mode the user can overwrite
this data by writing to the DSTo C-channel Register.
This access can be done anytime outside the frame
pulse interval of the ST-BUS frame. Data written in
the current ST-BUS frame will only appear in the Cchannel of the following frame.
The least significant bit (B0) of the C-channel
Register, selects between the control register or the
diagnostic register. Setting the B0 of the C-channel
Register to ’0’ allow access to the control register.
Setting the LSB of the C-channel Register to ’1’ allow
access to the diagnostic register. The interpretation
of each register is defined in Tables 13 and 14 for NT
mode or Tables 16 and 17 for the TE mode.
It is important to note that in TE mode, the C-channel
Diagnostic Register should be cleared while the
device is not in the active state (IS0, IS1 ≠ 1,1). This
is accomplished by setting the ClrDia bit of the Cchannel Control Register to 1 until the device is
activated. In serial control mode, the C-channel on
the ST-BUS is loaded into the C-channel Control
Register in every ST-BUS frame; the user should
make sure that a 1 is written to the ClrDia bit in every
frame. However, in parallel control mode the user
needs to set the ClrDia bit only once to keep the
MT8930C
Data Sheet
Diagnostic Register cleared. Once full activation is
achieved the Diagnostic Register can be written to in
order to enable the various test functions.
HDLC Transceiver
The HDLC Transceiver handles the bit oriented
protocol structure and formats the D-channel as per
level 2 of the X.25 packet switching protocol defined
by CCITT. It transmits and receives the packetized
data (information or control) serially in a format
shown in Figure 15, while providing data
transparency by zero insertion and deletion. It
generates and detects the flags, various link channel
states and the abort sequence. Further, it provides a
cyclic redundancy check on the data packets using
the CCITT defined polynomial. In addition, it can
recognize a single byte, dual byte or an all call
address in the received frame. There is also a
provision to disable the protocol functions and
provide transparent access to either serial port
through the microprocessor port. Other features
provided by the HDLC include, independent port
selection for transmit and received data (e.g.
transmit on S-Bus and receive from ST-BUS),
selectable 16 or 64 kbit/s D-channel as well as an
HDLC loopback from the transmit to the receive port.
These features are enabled through the HDLC
control registers (see Tables 6 and 7).
HDLC Frame Format
All frames start with an opening flag and end with a
closing flag as shown in Figure 15. Between these
two flags, a frame contains the data and the frame
check sequence (FCS).
FLAG
DATA FIELD
FCS
FLAG
One
Byte
n Bytes
(n ≥ 2)
Two
Bytes
One
Byte
Figure 15 - Frame Format
i) Flag
The flag is a unique pattern of 8 bits (01111110)
defining the frame boundary. The transmit section
generates the flags and appends them automatically
to the frame to be transmitted. The receive section
searches the incoming packets for flags on a
bit-by-bit
basis
and
establishes
frame
synchronization. The flags are used only to identify
and synchronize the received frame and are not
transferred to the FIFO.
ii) Data
The data field refers to the Address, Control and
Information
fields
defined
in
the
CCITT
recommendations. A valid frame should have a data
field of at least 16 bits. The first and second byte in
the data field is the address of the frame.
iii) Frame Check Sequence (FCS)
The 16 bits following the data field are the frame
check sequence bits. The generator polynomial is:
G(x)=x16+x12+x5+1
The transmitter calculates the FCS on all bits of the
data field and transmits the complement of the FCS
with most significant bit first. The receiver performs
a similar computation on all bits of the received data
but also includes the FCS field. The generating
polynomial will assure that if the integrity of of the
transmitted data was maintained, the remainder will
have a consistent pattern and this can be used to
identify, with high probability, any bit errors occurred
during transmission. The error status of the received
packet is indicated by B7 and B6 bits in the HDLC
Status Register.
iv) Zero Insertion and Deletion
The transmitter, while sending either data from the
FIFO or the 16 bits FCS, checks the transmission on
a bit-by-bit basis and inserts a ZERO after every
sequence of five contiguous ONEs (including the last
five bits of FCS) to ensure that the flag sequence is
not imitated. Similarly the receiver examines the
incoming frame content and discards any ZERO
directly following the five contiguous ONEs.
v) Abort
The transmitter aborts a frame by sending a zero
followed by seven consecutive ONEs. The FA bit in
the HDLC Control Register 2 along with a write to the
HDLC Transmit FIFO enables the transmission of an
abort sequence instead of the byte written to the
register (to have a valid abort there must be at least
two bytes in the packet). On the receive side, a
frame abort is defined as seven or more contiguous
ONEs occurring after the start flag and before the
end flag of a packet. An interrupt can be generated
on reception of the abort sequence using FA bit in
the HDLC Interrupt Mask/Vector Registers (refer to
Tables 9 and 10).
15
MT8930C
Interframe Time Fill
When the HDLC Tranceiver is not sending packets,
the transmitter can be in one of two states mentioned
below depending on the status of the IFTF bit in the
HDLC Control Register 1.
i) Idle State
The Idle state is defined as 15 or more contiguous
ONEs. When the HDLC Protocoller is observing this
condition on the receiving channel, the Idle bit in the
HDLC Status Register is set HIGH. On the transmit
side, the Protocoller ends the transmission of all
ones (idle state) when data is loaded into the
transmit FIFO.
CCITT I.430 Specification requires every TE that
does not have layer 2 frames to transmit, to send
binary ONEs on the D-channel. In this manner, other
TEs on the line will have the opportunity to access
the D-channel using the priority mechanism circuitry.
ii) Flag Fill State
The HDLC Protocoller transmits continuous flags
(7EHex) in Interframe Time Fill state and ends this
state when data is loaded into the transmit FIFO.
The reception of the interframe time fill will have the
effect of setting the idle bit in the HDLC Status
Register is set to ’0’.
HDLC Transmitter
On power up, the HDLC transmitter is disabled and
in the idle state. The transmitter is enabled by
setting the TxEN bit in the HDLC Control Register 1.
To start a packet, the data is written into the 19 byte
Transmit FIFO starting with the address field. All the
data must be written to the FIFO in a bytewide
manner. When the data is detected in the transmit
FIFO, the HDLC protocoller will proceed in one of the
following ways:
1) If the transmitter is in idle state, the present byte
of ones is completely transmitted before sending
the opening flag. The data in the transmit FIFO is
then transmitted. A TE transmitting on the Dchannel will use the contention circuitry
described previously in D-channel Priority
Mechanism to access this channel.
2) If the transmitter is in the flag fill state, the
flag presently being transmitted is used as the
opening flag for the packet stored in the transmit
FIFO.
16
Data Sheet
3) If the HDLC transmitter is in transparent
data mode, the protocol functions are disabled
and the data in the transmit FIFO is transmitted
without a framing structure.
To indicate that the particular byte is the last byte of
the packet, the EOP bit in the HDLC Control Register
2 must be set before the last byte is written into the
transmit FIFO. The EOP bit is cleared automatically
when the data byte is written to the FIFO. After the
transmission of the last byte in the packet, the frame
check sequence (16 bits) is sent followed by a
closing flag. If there is any more data in the transmit
FIFO, it is immediately sent after the closing flag.
That is, the closing flag of a packet is also used as
the opening flag the the next packet.
However, CCITT I.430 and ANSI T1.605
Recommendations state that after the successful
transmission of a packet, a TE must lower its priority
level within the specified priority class. The user can
meet this requirement by loading the Tx FIFO with no
more than one packet and then waiting for the
DCack bit to go to zero, or for an HDLC interrupt by
the TEOP bit in the HDLC Interrupt Status Register,
before attempting to load a new packet. If there is no
more data to be transmitted, the transmitter assumes
the selected link channel state.
During the transmission of either the data or the
frame check sequence, the Protocol Controller
checks the transmitted information on a bit by bit
basis to insert a ZERO after every sequence of five
consecutive ONEs. This is required to eliminate the
possibility of imitating the opening or closing flag, the
idle code or an abort sequence.
i) Transmit Underrun
A transmit underrun occurs when the last byte
loaded into the transmit FIFO was not ‘flagged’ with
the ‘end of packet’ (EOP) bit and there are no more
bytes in the FIFO. In such a situation, the Protocol
Controller transmits the abort sequence (zero and
seven ones) and moves to the selected link channel
state.
Conversely, in the event that the transmit FIFO is full,
any further writes will overwrite the last byte in the
Transmit FIFO.
ii) Abort Transmission
If it is desired to abort the packet currently being
loaded into the transmit FIFO, the next byte written
to the FIFO should be ‘flagged’ to cause this to
happen. The FA bit of the HDLC Control Register 2
MT8930C
Data Sheet
must be set HIGH, before writing the next byte into
the FIFO. This bit is cleared automatically once the
byte is written to the Transmit FIFO. When the
‘flagged’ byte reaches the bottom of the FIFO, a
frame abort sequence is sent instead of the byte and
the transmitter operation returns to normal. The
frame abort sequence is ignored if the packet has
less then two bytes.
iii) Transparent Data Transfer
The Trans bit (B4) in the HDLC Control Register 2
can be set to provide transparent data transfer by
disabling the protocol functions. The transmitter no
longer generates the Flag, Abort and Idle sequences
nor does it insert the zeros and calculate the FCS.
It should be noted that none of the protocol related
status or interrupt bits are applicable in transparent
data transfer state. However, the FIFO related
status and interrupt bits are pertinent and carry the
same meaning as they do while performing the
protocol functions.
HDLC Receiver
After a reset on power up, the receive section is
disabled. Address detection is also disabled when a
reset occurs. If address detection is required, the
Receiver Address Registers are loaded with the
desired address and the ADRec bit in the HDLC
Control Register 1 is set HIGH. The receive section
can then be enabled by RxEN bit in this same
Control Register 1. All HDLC interrupts are masked,
thus the desired interrupt signal must be unmasked
through the HDLC Interrupt Mask Register. All active
interrupts are cleared by reading the HDLC Interrupt
Status Register.
i) Normal Packets
After initialization as explained above, the serial data
starts to be clocked in and the receiver checks for
the idle channel and flags. If an idle channel is
detected, the ‘Idle’ bit in the HDLC Status Register is
set HIGH. Once a flag is detected, the receiver
synchronizes itself in a bytewide manner to the
incoming data stream.
The receiver keeps
resynchronizing to the flags until an incoming packet
appears. The incoming packet is examined on a
bit-by-bit basis, inserted zeros are deleted, the FCS
is calculated and the data bytes are written into the
19 byte Receive FIFO. However, the FCS and other
control characters, i.e., flag and abort , are never
stored in the Receive FIFO. If the address detection
is enabled, the address field following the flag is
compared to the bytes in the Receive Address
Registers.
If one byte address recognition is
enabled, the address field is one byte long and it is
compared with the six most significant bits in
address recognition register 1. If two byte address
recognition is enabled, the address field is two bytes
long and is compared with the address recognition
registers 1 and 2. The address byte can also be
recognized if it is an all call address (i.e., seven most
significant bits are 1). If a match is not found, the
entire packet is ignored, nothing is written to the
Receive FIFO and the receiver waits for the next
packet. If the active address byte is valid, the packet
is received in normal fashion.
All the bytes written to the receive FIFO are flagged
with two status bits. The status bits are found in the
HDLC status register and indicate whether the byte
to be read from the FIFO is the first byte of the
packet, the middle of the packet, the last byte of the
packet with good FCS or the last byte of the packet
with bad FCS. This status indication is valid for the
byte which is to be read from the Receive FIFO.
The incoming data is always written to the FIFO in a
bytewide manner. However, in the event of data sent
not being a multiple of eight bits, the software
associated with the receiver should be able to pick
the data bits from the LSB positions of the last byte
in the received data written to the FIFO. The
Protocoller does not provide any indication as to how
many bits this might be.
ii) Invalid Packets
In TE mode, if there are less than 25 data bits
between the opening and closing flags, the packet is
considered invalid and the data never enters the
receive FIFO (inserted zeros do not form part of the
valid bit count). This is true even with data and the
abort sequence, the total of which is less than 25
bits. The data packets that are at least 25 bits but
less than 32 bits long are also invalid, but not
ignored. They are clocked into the receive FIFO and
tagged as having bad FCS.
In NT mode, however, all the data packets that are
less than 32 bits long are considered invalid. They
are clocked into the receive FIFO with “Bad FCS”
status.
iii) Frame Abort
When a frame abort is received, the EOPD and FA
bits in the HDLC Interrupt Status Register are set.
The last byte of the aborted packet is written to the
FIFO with a status of “Packet Byte”. If there is more
than one packet in the FIFO, the aborted packet is
17
MT8930C
Data Sheet
distinguished by the fact that it has no “Last Byte”
status on any of its bytes.
status and interrupt bits are pertinent and carry the
same meaning as they do while performing the
protocol functions.
iv) Idle Channel
vi) Receive Overflow
While receiving the idle channel, the idle bit in the
HDLC status register remains set.
v) Transparent Data Transfer
By setting the Trans bit in the HDLC Control Register
2 to select the transparent data transfer, the receive
section will disable the protocol functions like Flag/
Abort/Idle detection, zero deletion, CRC calculation
and address comparison. The received data is
shifted in from the active port and written to receive
FIFO in bytewide format.
Receive overflow occurs when the receive section
attempts to load a byte to an already full receive
FIFO. All attempts to write to the full FIFO will be
ignored until the receive FIFO is read. When
overflow occurs, the rest of the present packet is
ignored as the receiver will be disabled until the
reception of the next opening flag.
It should be noted that none of the protocol related
status or interrupt bits are applicable in transparent
data transfer state. However, the FIFO related
BIT
NAME
DESCRIPTION
B7
NA
B6-B3
NA(1)
B2
IRQ/NDA
The state of this pin will select the mode of the IRQ/NDA pin.
A ’0’ will enable the IRQ pin for HDLC interrupts.
A ’1’ will enable the New Data Available signal which identifies the access time to the
synchronous registers. (If NDA is enabled, the HDLC interrupts are disabled.)
B1
M/Sen
A ’0’ will enable the transmission of the M(2) or S bit as selected in the NT Mode C-channel
Register (refer to Table 13). The selection of M or S is determined by the HALF signal
(refer to functional timing).
A ’1’ will disable this feature forcing the M and S bits to binary zero.
B0
P/SC
The Parallel/Serial Control bit selects the source of the control channel. If ’0’, then the Cchannel Register is access through the ST-BUS stream. If ’1’, then the C-channel
Register is accessed through the microprocessor port.
A ‘1’ will allow access to Control Register 1 and Master Status Register.
A ‘0’ will prevent it.
Keep at ’0’ for normal operation.
Table 3. Master Control Register (Read/Write Add. 00000 B)
Note 1:
Note 2:
These bits have no designated memory space and will read as the last values written to the microprocessor port.
The transmission of M=1 is used for a second level of multiframing.
BIT
NAME
B7
NA
B6
RxDIS
B5-B0
NA
DESCRIPTION
Keep at ‘0’ for normal operation.
When set to ‘1’, this bit disables the S-Bus signal receiver. It can be used, for example, to
force INFO4 to INFO2 transition in the NT state machine while receiving INFO3 from the
TE.
Keep at ‘0’ for normal operation.
Table 4. Control Register 1 (Write Add. 10000B)
18
MT8930C
Data Sheet
BIT
NAME
DESCRIPTION
B7
CH3i(3)
If ’1’, then the ST-BUS channel 3 input port is enabled (B2-channel).
If ’0’, then the channel is disabled, and will read FFH.
B6
CH2i(3)
If ’1’, then the ST-BUS channel 2 input port is enabled (B1-channel).
If ’0’, then the channel is disabled, and will read FFH.
B5
CH1i(3)
If ’1’, then the ST-BUS channel 1 input port is enabled (C-channel).
If ’0’, then the channel is disabled, and will read 00H.
B4
CH0i(3)
If ’1’, then the ST-BUS channel 0 input port is enabled (D-channel).
If ’0’, then the channel is disabled, and will read FFH.
B3
CH3o(3)
If ’1’, then the ST-BUS channel 3 output port is enabled (B2-channel).
If ’0’, then the channel is disabled and it will be placed in High impedance.
B2
CH2o(3)
If ’1’, then the ST-BUS channel 2 output port is enabled (B1-channel).
If ’0’, then the channel is disabled and it will be placed in High impedance.
B1
CH1o(3)
If ’1’, then the ST-BUS channel 1 output port is enabled (C-channel).
If ’0’, then the channel is disabled and it will be placed in High impedance
B0
CH0o(3)
If ’1’, then the ST-BUS channel 0 output port is enabled (D-channel).
If ’0’, then the channel is disabled and it will be placed in High impedance.
Table 5. ST-BUS Control Register (Read/Write Add. 00001 B)
Note 3: All ST-BUS channels are enabled in controllerless mode.
BIT
NAME
DESCRIPTION
B7
TxEn
A ’1’ enables the HDLC transmitter for the selected D-channel (i.e., ST-BUS or S-Bus).
A ’0’ disables the HDLC transmitter (i.e., an all 1s signal will be sent).
B6
RxEn
A ’1’ enables the HDLC receiver for the selected D-channel (i.e., ST-BUS or S-Bus).
A ’0’ disables the HDLC receiver (i.e., an all 1s signal will be received).
B5
ADRec
B4
TxPrtSel
This bit selects the port of the HDLC transmitted D-channel.
A’1’ selects the S-Bus port. A ’0’ selects the ST-BUS port.
B3
RxPrtSel
This bit selects the port of the HDLC received D-channel.
A ’1’ selects the S-Bus port. A ’0’ selects the ST-BUS port.
B2
IFTF
B1
NA
B0
HLoop
If ’1’, then the address recognition is enabled. This forces the receiver to recognize only
those packets having the unique address as programmed in the Receive Address
Registers or if the address byte is the All-Call address (all 1s).
If ’0’, then the address recognition is disabled and every valid packet is stored in the
received FIFO.
This bit selects the Inter Frame Time Fill.
A ’1’ selects continuous flags. A ’0’ selects an all 1’s idle state.
Keep at ’0’ for normal operation.
A ’1’ will activate the HDLC loopback where the transmitted D-channel is looped back to
the received D-channel(1). In NT mode, the transmission of the packet is not affected. In
TE Mode, however, the DReq bit of C-channel Control Register must be set to ‘1’ for the
packet to be transmitted to the S-Bus.
A ’0’ disables the loopback.
Table 6. HDLC Control Register 1 (Read/Write Add. 00010B)
Note 1: The HDLC receiver must be enabled as well as the designated channel.
19
MT8930C
Data Sheet
BIT
NAME
DESCRIPTION
B7-B5
NA
B4
Trans
A ’1’ will place the HDLC in a transparent mode. This will perform the serial to parallel or
parallel to serial conversion without inserting or deleting the opening and closing flags,
CRC bytes or zero insertion. The source or destination of the data is determined by the
port selection bits in the HDLC Control Register 1.
B3
RxRst
A transition from ‘0’ to ’1’ will reset the receive FIFO. This causes the receiver to be
disabled until the reception of the next flag. (The status Register will identify the RxFIFO
as being empty). The device resets this bit to ‘0’ immediately after clearing the receive
FIFO.
B2
TxRst
A transition from ‘0’ to ’1’ will reset the transmit FIFO. This causes the transmitter to
clear all data in the TxFIFO. The device resets this bit to ‘0’ immediately after clearing
the transmit FIFO.
B1
FA(2)
A ’1’ will ’tag’ the next byte written to the transmit FIFO and cause an abort sequence to
be transmitted once it reaches the bottom of the FIFO.
B0
EOP(2)
Keep at ’0’ for normal operation.
A ’1’ will ’tag’ the next byte written to the transmit FIFO and cause an end of packet
sequence to be transmitted once it reaches the bottom of the FIFO.
Table 7. HDLC Control Register 2 (Write Add. 00011 B)
Note 2: These bits will be reset after a write to the TxFIFO
BIT
NAME
DESCRIPTION
B7-B6
RxByte
Status
These two bits indicate the status of the received byte which is ready to be read from the
19 deep received FIFO. The status is encoded as follows:
B7 -B6
0 - 0
- Packet Byte
0 - 1
- First Byte
1 - 0
- Last Byte (Good FCS)
1 - 1
- Last Byte (Bad FCS)
B5-B4
RxFIFO
Status
These two bits indicate the status of the 19 deep receive FIFO. This status is encoded
as follows:
B5 - B4
0 - 0
- Rx FIFO Empty
0 - 0
- ≤14 Bytes
1 - 0
- Rx FIFO Overflow
1 - 1
- ≥15 Bytes
B3-B2
TxFIFO
Status
These two bits indicate the status of the 19 deep transmit FIFO as follows:
B3 - B2
0 - 0
- Tx FIFO Full
0 - 1
- ≥5 Bytes
1 - 0
- Tx FIFO Empty
1 - 1
- ≤ Bytes
B1
Idle
If ’1’, an idle channel state has been detected.
B0
Int
If ’1’ an unmasked asynchronous interrupt has been detected.
Table 8. HDLC Status Register (Read Add. 00011B)
20
MT8930C
Data Sheet
BIT
NAME
DESCRIPTION
B7
EnDcoll
B6
EnEOPD
A ’1’ will enable the received End of Packet interrupt.
A ’0’ will disable it.
B5
EnTEOP
A ’1’ will enable the transmit End of Packet interrupt.
A ’0’ will disable it.
B4
EnFA
B3
EnTxFL
A ’1’ will enable the Transmit FIFO Low interrupt.
A ’0’ will disable it.
B2
EnTxFun
A ’1’ will enable the Transmit FIFO Underrun interrupt.
A ’0’ will disable it.
B1
EnRxFF
A ’1’ will enable the Receive FIFO Full interrupt.
A ’0’ will disable it.
B0
EnRxFov
A ’1’ will enable the Receive FIFO Overflow interrupt.
A ’0’ will disable it.
A ’1’ will enable the D-channel collision interrupt.
A ’0’ will disable it. This bit is available only in TE mode.
A ’1’ will enable the Frame Abort interrupt.
A ’0’ will disable it.
Table 9. HDLC Interrupt Mask Register (Write Add. 00100 B)
BIT
NAME
DESCRIPTION
B7
Dcoll(1)
A ’1’ indicates that a collision has been detected on the D-channel (i.e., received E-bit
does not match with transmitted D-bit). This bit is available only in TE mode and when the
HDLC transmitter is enabled. It always reads ’0’ in NT mode.
B6
EOPD(1)
A ’1’indicates that an end of packet has been detected on the HDLC receiver. This can be
in the form of a flag, an abort sequence or as an invalid packet.
B5
TEOP(1)
A ’1’ indicates that the transmitter has finished sending the closing flag of the last packet in
the Tx FIFO, and the internal priority level is reduced from high to low.
B4
FA(1)
A ’1’ indicates that the receiver has detected a frame abort sequence on the received data
stream.
B3
TxFL(1)
A ’1’ indicates that the device has only four Bytes remaining in the Tx FIFO. This bit has
significance only when the Tx FIFO is being depleted and not when it is getting loaded.
B2
TxFun(1)
A ’1’ indicates that the Tx FIFO is empty without being given the ’end of packet’ indication.
The HDLC will transmit an abort sequence after encountering an underrun condition.
B1
RxFF(1)
A ’1’ indicates that the HDLC controller has accumulated at least 15 bytes in the Rx
FIFO.
B0
RxFov(1)
A ’1’ indicates that the Rx FIFO has overflown (i.e., an attempt to write to a full Rx FIFO).
The HDLC will always disable the receiver once the receive overflow has been detected.
The receiver will be re-enabled upon detection of the next flag.
Table 10. HDLC Interrupt Status Register (Read Add. 00100 B)
Note 1:
All interrupts will be reset after a read to the HDLC Interrupt Status Register.
21
MT8930C
BIT
B7-B2
NAME
Data Sheet
DESCRIPTION
R1A7-R1A2 A six bit mask used to interrogate the first byte of the received address (where B7 is MSB).
If address recognition is enabled, any packet failing the address comparison will not be
stored in the Rx FIFO.
B1
NA
B0
A1En
Not applicable to address recognition.
If ’0’, the first byte of the address field will not be used during address recognition.
If ’1’ and the address recognition is enabled, the six most significant bits of the first
address byte will be compared with the first six bits of this register.
Table 11. HDLC Address Recognition Register 1 (Read/Write Add. 00110B)
BIT
B7-B1
B0
NAME
DESCRIPTION
R2A7-R2A1 A seven bit mask used to interrogate the second byte of the received address (where B7 is
MSB). If address recognition is enabled, any packet failing the address comparison will
not be stored in the Rx FIFO. This mask is ignored if the address is a Broadcast (i.e., R2A
= 1111111).
A2En
If ’0’, the second byte of the address field will not be used during address recognition.
If ’1’ and the address recognition is enabled, the seven most significant bits of the second
address byte will be compared with the first seven bits of this register.
Table 12. HDLC Address Recognition Register 2 (Read/Write Add. 00111 B)
BIT
NAME
DESCRIPTION
B7
AR
Setting this bit will initiate the activation of the S-Bus.
If ’0’, the device will remain in the present state.
B6
DR
Setting this bit will initiate the deactivation of the S-Bus.
If ’0’, the device will remain in the present state. This bit has priority over AR.
B5
DinB
If ’1’, the D-channel will be placed in the B1 timeslot allocating 64 kbit/s to the D-channel.(1)
If ’0’, the D-channel will assume its position with a 16 kbit/s bandwidth.(1)
B4
Timing
A ’0’ will set the NT in a short passive bus configuration using a fixed timing source (no
compensation for line length).
A ’1’ will set the NT in a point-to-point or extended passive bus configuration with adaptive
timing compensation.
B3
M/S
B2
HALF
B1
TxMFR
A ’1’ in this bit, while HALF = 0, will force the transmission of a multiframe sequence in the
Fa and N bits, i.e., Fa=1 and N=0. A ‘0’ will resume normal operation, i.e., Fa=0 and N=1.
B0
RegSel
If the register select bit is set to ’1’, the control register is redefined as the diagnostic
register. A ’0’ give access to the control register.
This bit represents the state of the transmitted M/S-bit. M when HALF=0 and S when
HALF=1.
The state of this bit identifies which half of the frame will be transmitted on the SBus. The operation of this signal is similar to that of the HALF pin.
Table 13. NT Mode C-channel Control Register(2) (Write Add. 01000B and B0 = 0)
Note 1:
Note 2:
22
Allow one ST-BUS frame to input the C-channel and one ST-BUS frame to establish the connection.
The C-channel Control Register is updated once every ST-BUS frame. Therefore, this register should not be written to
more than once per frame, otherwise, the last access will override previous ones.
MT8930C
Data Sheet
BIT
NAME
DESCRIPTION
B7-B6
Loop
B5
FSync
If ’1’, the device will maintain frame synchronization even after losing the framing
sequence (i.e., if the device is transmitting INFO2 or INFO4 and this bit is set, the same
INFO signal will still be transmitted even if the frame sync sequence in the received signal
is lost).
If ’0’, synchronization will be declared when three consecutive framing sequences have
been detected without error.
B4
FLv
If ’1’, the frame sync sequence will violate the bipolar violation encoding rule.
If ’0’, the framing pattern resumes normal operation, i.e., Framing bit is a bipolar violation.
B3
Idle
Setting this bit to ’1’ will force an all 1s signal to be transmitted on the line.
B2
Echo
Setting this bit to ’1’ will force all D-echo bits (E) to zero.
B1
Slave
If ’1’, the device will operate in a NT slave mode. This allows the device to be used at the
terminal equipment end of the line while receiving its clocks from an external source.
B0
RegSel
The status of these two bits determine which type of loopback is to be performed:
B7 - B6
0 - 0 - no loopback active
0 - 1 - near end loopback LTx to LRx
1 - 0 - digital loopback DSTi to DSTo
1 - 1 - remote loopback LRx to LTx
If the register select bit is set to ’1’, the control register is redefined as the diagnostic
register. A ’0’ gives access to the control register.
Table 14. NT Mode C-channel Diagnostic Register (Write Add. 01000B and B0 = 1)
BIT
NAME
DESCRIPTION
B7
Sync/BA
This bit is set when the device has achieved frame synchronization while the activation
request is asserted (DR = 0 and AR = 1). If there is a deactivation request or AR is low
(DR = 1 or AR = 0), this bit indicates the presence of bus activity(1). A bus activity identifies
the reception of INFO frames (INFO1 or INFO3).
B6-B5
IS0-IS1
Binary encoded state sequence.
IS0 - IS1
0 - 0
- deactivated
0 - 1
- pending deactivation
1 - 0
- pending activation
1 - 1
- activated
B4
RxMCH
Following a ‘0’ input at the HALF pin or HALF bit in the C-channel Control Register, the
state of this bit reflects the received maintenance Q-channel (received in the Fa bit position
during multiframing).
This bit will always read ‘1’ if multiframing is not used.
B3-B0
NA
Note 1:
Note 2:
These bits will read ’1’.
Table 15. NT Mode Status Register(2) (Read Add. 01001 B)
Bus activity is set when three zeros are received in a time period equivalent to 48 bits or 250 µs. It is reset when 128
consecutive ones are received.
The Status Register is updated internally once every ST-BUS frame. Therefore, more than one read access per frame will
return the same value.
23
MT8930C
Data Sheet
BIT
NAME
DESCRIPTION
B7
AR
Setting this bit will initiate the activation of the S-Bus.
If ’0’, the device will remain in the present state.
B6
DR
Setting this bit will initiate the deactivation of the S-Bus.
If ’0’, the device will remain in the present state. This bit has priority over AR.
B5
DinB
If ’1’, the D-channel will be placed in the B1 timeslot allocating 64 kbit/s to the
D-channel. (1)
If ’0’, the D-channel will assume its position with a 16 kbit/s bandwidth.(1)
B4
Priority
The status of this bit selects the priority class of the terminal equipment. A ’1’ selects the
high priority and a ’0’ selects the low priority.
B3
DReq
This bit is used to request or relinquish the D-channel on the S-Bus when the D-channel
source is the ST-BUS. A ’1’ will request the D-channel, a ’0’ will relinquish it.
Keep at ’0’ when the D-channel source is the HDLC transmitter.
B2
TxMCH
B1
ClrDia
A ’1’ will clear the contents of the Diagnostics Register.
A ’0’ will enable the maintenance functions found in the Diagnostic Register.
This bit should be set to 1 as long as the device is not fully active (IS0, IS1 ≠ 1,1).
B0
RegSel
If the register select bit is set to ’1’, the control register is redefined as the diagnostic
Register. A ’0’ gives access to the Control Register.
The state of this bit will be transmitted in the maintenance channel (Q-channel).
Table 16. TE Mode C-channel Control Register
Note 1:
Note 2:
(2)
(Write Add. 01000B and B0 = 0)
Allow one ST-BUS frame to input the C-channel and one ST-BUS frame to establish the connection.
The C-channel Control Register is updated once every ST-BUS frame. Therefore, this register should not be written to
more than once per frame, otherwise, the last access will override previous ones.
BIT
NAME
DESCRIPTION
B7-B6
Loop
B5
FSync
B4
FLv
If ’1’, the frame sync sequence will violate the normal bipolar encoding rule.
If ’0’, the framing pattern resumes normal operation, i.e., framing bit will be a bipolar
violation.
B3
Idle
If ’1’, an all 1s signal is transmitted on the line.
If ’0’, the transmitter will resume normal operation.
B2-B1
NA
Unused.
B0
RegSel
The status of these two bits determine which type of loopback is to be performed:
B7 - B6
0 - 0 - no loopback active
0 - 1 - near end loopback LTx to LRx
1 - 0 - digital loopback DSTi to DSTo
1 - 1 - remote loopback LRx to LTx
If ’1’, the device will maintain frame synchronization even after losing the frame sync
sequence (i.e., if the device is transmitting INFO3 and this bit is set, INFO3 will still be
transmitted even if the frame sync sequence in the received signal is lost).
If ’0’, synchronization will be declared when three consecutive framing sequences have
been detected.
If the register select bit is set to ’1’, the control register is redefined as the diagnostic
register. A ’0’ gives access to the control register.
Table 17. TE Mode Diagnostic Register (Write Add. 01000B and B0 = 1)
24
MT8930C
Data Sheet
BIT
NAME
DESCRIPTION
B7
Sync/BA
This bit is set if the device has achieved frame synchronization while the activation request
is asserted (DR = 0 and AR = 1). If there is a deactivation request or that AR is low ( DR =
1 or AR = 0), this pin indicates the presence of bus activity(1). A bus activity identifies the
reception of INFO frames (INFO2 or INFO4).
B6-B5
IS0-IS1
Binary encoded state sequence.
IS0 - IS1
0 - 0
- deactivated
0 - 1
- synchronized
1 - 0
- activation request
1 - 1
- activated
B4
M/S
B3
HALF
The state of this bit identifies which half of the S-Bus frame is currently being output on the
ST-BUS.
B2
RxMFR
A ’1’ when HALF=0 indicates that the multiframe pattern on Fa and N has been detected.
B1
Priority
The status of this bit indicates the internal priority of the device within the designated
priority class. If 1, then it has high priority within the priority class designated in B4 of
control register. If 0, then it has low priority within the priority class designated in B4 of
control register.
B0
DCack
A ’1’ indicates that the device has gained access to the D-channel and has transmitted an
opening flag. This bit is reset to ‘0’ when the closing flag of the last packet in the TxFIFO is
transmitted and the internal priority is reduced from high to low. A collision during
transmission will also reset this bit back to ‘0’.
This bit respresents the state of the received M/S-bit. M when HALF=0 and S when
HALF=1
Table 18. TE Mode Status Register (2) (Read Add. 01001 B)
Note 1:
Note 2:
Bus activity is set when three zeros are received in a time period equivalent to 48 bits or 250 µs. It is reset when 128
consecutive ones are received.
The Status Register is updated internally once every ST-BUS frame. Therefore, more than one read access per frame will
return the same value.
BIT
NAME
DESCRIPTION
B7-B2
NA
B1*
INFO1
In TE mode, this bit is set to ‘1’ only when the device is transmitting INFO1.
Not available in NT mode.
B0*
INFO0
In NT or TE mode, this bit is set to ‘1’ only when the device is transmitting INFO0.
Not available.
Table 19. Master Status Register (Read Add. 10010B)
*
These two bits can be used along with status bits IS0 and IS1 to distinguish between states F6/F8 and F4/F5 of the device’s state machine
in TE mode. Please refer to “State Machine” section of Application Note MSAN-141 for further details.
25
MT8930C
Data Sheet
Applications
Both the MT8930C and MT9094 are controlled and
monitored by a microprocessor to implement various
features and control functions. Signalling may be
performed by scanning the keypad and generating
appropriate messages to be packetized by the HDLC
section of the SNIC and transmitted via the Dchannel. A twelve segment, non-multiplexed LCD
display can be connected directly to the S12-S1
outputs to provide various status and call progress
indicators.
The MT8930C is useful in a wide variety of ISDN
applications.
Being used at both the Network
Termination (NT) and Terminal Equipment (TE) ends
of the line, the SNIC finds application on digital
subscriber line cards and in full featured digital
telephone sets.
The SNIC can be combined with the MT8971B/72B
to implement an NT1 function(with biphase line code
on the U interface) as shown in Figure 16. It can
also be combined with the MT8910 to implement an
ISDN NT1 function (with 2B1Q line code on the U
interface) as shown in Figure 17. The MT8930C is
configured in NT mode, acting as a master to the Sinterface line, while the MT8971B/72B or the
MT8910 operates in slave mode and derives its
timing from the U-interface line originating from the
central office.
For Figure 16, communication
between the two devices is done via the serial STBUS ports. Control and status of the SNIC is
communicated with the MT8971B/72B through the
C-channel of the ST-BUS.
Figure 18 illustrates the use of the SNIC in
conjunction with the MT9094 to implement a 2B+
D, ISDN telephone set. The MT9094 provides such
features as A/D and D/A conversion, handset
interface, handsfree operation and tone ringer. PCM
encoded voice is passed from the MT9094 to the
SNIC via the ST-BUS port for transmission on one of
the B-channels. The second B-channel is available
for transmission of data. These two devices have
been designed to connect together with virtually no
interconnection components.
MT8930C
RTx
LTx
1:2*
DSTi
DSTo
LRx
+5V
1.5 nF
390 Ω
22 nF
LOUT
2:1
F0b
C4b
+5V
Star
Cmode
47 Ω
LIN
MS0
P/SC
NT
Rsti
10kΩ
1:2*
The microprocessor interface for the SNIC was
designed around a multiplexed bus architecture
which may be found with most Intel processors/
controllers or a few Motorola processors. In the
event that your choice of processors is restricted, a
simple application circuit can convert the nonmultiplexed bussing to that of a multiplexed
architecture. Figure 19 provides an to interface the
MC6802 or the MC6809 microprocessors.
DSTi
C4b
R‡
Interfacing to Non-Multiplexed Busses
DSTo
10 µF
VBias
In multidrop applications, a powered-off TE must not
load the line and prevent communications between
the NT and other TEs. To avoid such a situation, one
mechanical relay should be used to disconnect the
LTx pin and the LRx pin from the line transformers.
MT8971B/72B
F0b
+5V
R‡
It must be noted, that the pseudo-ternary line code
will tolerate line reversals within the LRx and LTx pair
between the NT and TE. However, reversal of the
TE transmit pair between two or more TEs will make
the S-interface inoperable.
MS1
MS2
OSC1
VREF
VBias
OSC2
0.33 µF
1.0 µF
10.24 MHz XTAL
33 pF
0.33 µF
0.33 µF
33 pF
+5V
DC to DC
Converter
‡100Ω
Figure 16 - NT1 Function
26
terminating resistor
MT8930C
Data Sheet
Microprocessor
Termination
Network
RTx
Lout+
C4b
F0b
R‡
VDD
MT8930C
NT Mode
Lin+
MT8910-1
DSLIC
MH89101
2:1
LTx
C4b
F0b
10µF
VBias
LinLout-
DSTi
DSTo
DSTo
DSTi
R‡
LRx
2:1
+5V
Power Supply
and
Power Feed
U Reference
Point
‡100Ω
S Reference
Point
terminating resistor
Figure 17 - NT1 using the MT8910-1 (DSLIC) and MT8930C (SNIC)
MT9094
MT8930C
DSTi
DSTo
DSTo
RTx
DSTi
HSPKR-
1:2
VDD
‡
R
HSPKR+
LTx
VBias
F0b
F0i
C4b
C4i
VDD
R‡
LRx
MMIC+
MIC-
Cmode
1:2
Handset
M+
Microphone
SPKR+
Speaker
2kΩ
SPKRData Port
IRQ
S12-1
Display
DATA1 SCLK CS
DC to DC
Converter
+5V
+5V
8051
10k
IRQ
‡
100Ω
terminating resistor
1
2
3
4
5
6
7
8
9
*
0
#
K
e
y
p
a
d
Figure 18 - ISDN Digital Telephone Set
27
MT8930C
Data Sheet
VDD
MC6802
74HCT245
(MC6809)
DIR
MT8930C
A
B
A0 - A7
Address
Decoder
AD0-AD7
G
CS
DS
R/W
VDD
VMA
74HCT245
AS
A
B
DIR
D0 - D7
R/W
G
E
EXTAL (Q)
Q
D
Connections to interface to MC6809
Figure 19 - Interfacing to the MC6802 Microprocessor
ETS 300-012 NT&TE Line Interface
Figures 20, 21 and 22 show the recommended line
interface circuits for meeting the ETS 300-012
requirements. These circuits assume that test
measurements are made using the "standard
reference
cord"
which
has
the
following
specifications:
C = 315pF to 350pF
R = 2.7Ω to 3.0Ω
Z > 75Ω
Length < 10m
Several types of transformers can be used:
L4096-X028 and L4096-X027 with the exceptions of
pin out; L4096-X029 and L4096-X030 are pin
compatible with L4096-X028-80.
In Figure 20, T1, 2 (Filtran TPW-3852-4) provides
isolation, longitudinal balance, impedance matching
and voltage level conversion. D5 and 6 (germanium)
ensure that the pulse shape lies within the center of
the various pulse templates. D1-4 protect the
MT8930C from line transients. C2, 3 decouple the
VBias voltage and optimize the receiver sensitivity.
R1 and C4 make up a low-pass filter recommended
for delaying the signal in TE applications, this filter
can also be used for NT applications allowing
common hardware for TE and NT applications. K1
isolates the MT8930C from the line for multidrop
applications in cases where the device is powered
down. L1 is 4-winding 5mH common mode choke to
suppress EMI on the 4-wire line.
•
Filtran TPW-3852-4 (Figure 20)
•
VAC T60403-L4096-X028 (Breakdown Voltage
4KV) (Figure 21)
•
VAC T60403-L4096-X027 Breakdown Voltage
2KV) (Figure 21)
The TPW-3852-4 is available from:
•
VAC T60403-L4096-X029 (Breakdown Voltage
4KV) (Figure 22)
•
VAC T60403-L4096-X030 (Breakdown Voltage
2KV) (Figure 22)
Filtran Ltd.
229 Colonnade Road
Nepean, Ontario
Canada
Telephone: (613) 226-1626
L4096-X029 and L4096-X030 are equivalent to
28
MT8930C
Data Sheet
In Figure 21, two types of diodes (germanium 1N270
or schottky MBD301) can be used for D5,6. 1N270
will leave more margin for pulse template and
longitudinal conversion loss. However, MBD301 will
leave more margin for impedance template. All other
components are as described previously for Figure
20.
The VAC Transformers are available from:
Germany
Vacuumschmelze GMBH
Postfach 22 53
D-63412 Hanau
Telephone: (49) 6181 380
Proprietary NT&TE Line Interface
For proprietary applications, where stringent
requirements such as ETS 300-012 do not have to
be met, the line interface circuit may be simpler and
consequently less expensive. Figure 23 shows such
a line interface circuit.
R1 should be chosen
according to the transformer selected and the
desired output signal level, typical values of R1 may
vary from 30Ω
to 75Ω .
Numerous types of
transformers may be used, including the following:
APC
Filtran
Filtran
Pulse
VAC
Canada
Votron Electronic Ltd.
250 Rayette Road
Concord, Ontario L4K 2G6
Telephone: (905) 669-9870
8016D (dual with common mode choke)
TEW-5660 (surface mount)
TPW-3852-4 (single)
PE-65495 (dual)
L4097-X028-80 (single)
In Figure 22, everything is the same as in Figure 21,
except transformer pin out.
USA
Vacuumschmelze Corporation
4027 Will Rogers Parkway
Oklahoma City, OK 73108
Telephone: (405) 943-9651
VDD
VDD
VDD
C1
MT8930C
D5
D1
LTx
T1
5
6
4
1
3
2
K1
VDD
D6
D2
+
C2
R2
C3
VBias
T2
3
VDD
R1
C4
6
5
Tx+
7
4
Tx-
9
2
10
1
2
R3
4
1
5
6
RxRx+
D3
LRx
VSS
L1
D4
K1
K1
D7
VDD
Parts List:
C1, 3 = 0.1µF Ceramic
C2 = 10µF Tantalum
C4 = 22pF
D1-4 = IN914
D5, 6 = IN270 Germanium
D7 = IN4003
K1 = 2 Form A or C Relay
(eg., Aromat TQ2E-5V)
L1 = VAC N4025-X034
R1 = 3k01 1%
R2, 3 = 100Ω 1%
T1, 2 = Filtran TPW-3852-4
Figure 20 - ETS 300-012 NT & TE Line Interface for Filtran TPW-3852-4
29
MT8930C
Data Sheet
VDD
VDD
VDD
C1
MT8930C
D5
D1
LTx
T1
1
4
2
5
3
6
K1
VDD
D6
D2
+
C2
L1
R2
C3
VBias
T2
VDD
R1
6
2
5
1
4
R3
5
7
4
9
2
10
1
D3
LRx
C4
3
6
D4
K1
TxRxRx+
Parts List:
C1, 3 = 0.1µF Ceramic
C2 = 10µF Tantalum
C4 = 22pF
D1-4 = IN914
D5, 6 = IN270 Germanium or
MBD301 Schottky
D7 = IN4003
K1 = 2 Form A or C Relay
(Aromat TQ2E-5V)
L1 = VAC N4025-X034
R1 = 3k01 1%
R2,3 = 100Ω 1%
T1, 2 = VAC T60403-L4096X027 or VAC T60403-L4096X028
K1
VSS
Tx+
VDD
D7
Figure 21 - ETS 300-012 NT & TE Line Interface for VAC X027 or X028
VDD
VDD
VDD
C1
MT8930C
D5
D1
T1
6
LTx
4
K1
VDD
D6
3
D2
1
+
C2
2
T2
1
VDD
2
5
R1
D3
6
D4
5
7
4
9
2
10
1
R3
4
K1
K1
D7
TxRxRx+
VDD
Parts List:
C1, 3 = 0.1µF Ceramic
C2 = 10µF Tantalum
C4 = 22pF
D1-4 = IN914
D5, 6 = IN270 Germanium or
MBD301 Schottky
D7 = IN4003
K1 = 2 Form A or C Relay
(Aromat TQ2E-5V)
L1 = VAC N4025-X034
R1 = 3k01 1%
R2,3 = 100Ω 1%
T1, 2 = VAC T60403-L4096X029 or VAC T60403-L4096X030
Figure 22 - ETS 300-012 NT & TE Line Interface for VAC X029 or X030
30
Tx+
3
LRx
C4
6
R2
C3
VBias
VSS
L1
5
MT8930C
Data Sheet
VDD
VDD
VDD
C1
MT8930C
D1
R1
T1
LTx
VDD
D2
R3
+
C2
C3
Tx+
Tx-
VBias
T2
VDD
R2
RxR4
Rx+
D3
LRx
D4
VSS
Parts List:
C1, 3 = 0.1µF Ceramic
C2 = 10µF Tantalum
D1-4 = IN914
R1 = see circuit description
R2 = 2k to 4k
R3, 4 = 100Ω
T1, 2 = see circuit description
Figure 23 - Proprietary NT & TE Line Interface
31
MT8930C
Data Sheet
Absolute Maximum Ratings*
Parameters
Symbol
Min
Max
Units
1
Supply Voltage
VDD
-0.3
7.0
V
2
Voltage on any I/O pin
VI/O
-0.3
VDD + 0.3
V
3
Current on any I/O pin
II/O
20
mA
4
Storage Temperature
TST
150
°C
5
Package Power Dissipation
PD
1000
mW
-65
* Exceeding these values may cause permanent damage. Functional operation under these conditions is not implied.
Recommended Operating Conditions - Voltages are with respect to ground (VSS) unless otherwise stated
Characteristics
Sym
Min
Typ‡
Max
Units
5.0
5.25
V
Test Conditions
1
Supply Voltage
VDD
4.75
2
Input High Voltage*
VIH
2.4
VDD
V
For 400mV noise margin
3
Input Low Voltage*
VIL
0
0.4
V
For 400mV noise margin
4
Load Resistance
(LTx)
RL
5
Load Capacitance
(LTx)
CL
6
Operating Temperature
250**
TOP
-40
Ω
With reference to VBias
32
pF
With reference to VBias
85
°C
‡ Typical figures are at 25°C and are for design aid only: not guaranteed and not subject to production testing.
* Except for CK/NT pin. See below.
** Including the transformer DC resistance.
DC Electrical Characteristics - Voltages are with respect to ground (VSS) unless otherwise stated
Characteristics
1
Supply Current
NT Activated
NT Deactivated
TE Activated
TE Deactivated
Sym
Min
Typ‡
Max
Units
14
8
16
10
20
11
25
14
mA
mA
mA
mA
IDDNA
IDDND
IDDTA
IDDTD
Test Conditions
Outputs loaded
Outputs unloaded
Outputs loaded
Outputs unloaded
2
Input High Voltage except for pin
CK/NT
VIH
2.0
V
Digital inputs
3
Input High Voltage for pin CK/NT
VIH
4
V
Digital input
4
Input Low Voltage except for pin
CK/NT
VIL
0.8
V
Digital inputs
5
Input Low Voltage for pin CK/NT
VIL
1
V
Digital input
6
Output High Current
IOH
10
15
mA
VOH=2.4V digital outputs
7
Output Low Current
IOL
5
7.5
mA
VOL=0.4V digital outputs
8
Input Leakage (except pin 8)
10
µA
VIN = VSS to VDD
9
Input Current for pin 8
25
µA
VIN = VSS to VDD
10
µA
VOUT = VSS to VDD
10
Output Leakage High Imped.
IiI
IOZ
‡ Typical figures are at 25°C and are for design aid only: not guaranteed and not subject to production testing.
AC Electrical Characteristics - Voltages are with respect to ground (VSS) unless otherwise stated
Characteristics
Sym
1
Input Voltage
(LRx)
VIN
2
Input Current
(LRx)
IIN
3
Output Voltage
(LTx)
VO
4
Output Current
(LTx)
5
Input Impedance
(LRx)
Min
Typ‡
Max
1.5
Units
Test Conditions
V
Peak with Ref. to VBias
µA
VI=1.5Vp Ref. VBias
@ f=0 - 100 kHz
1.5
V
Ref. VBias, RL=250Ω
IO
7.5
mA
VO=1.5Vp Ref. VBias, RL=250Ω
ZIN
20
kΩ
f = 100 kHz
70
‡ Typical figures are at 25°C and are for design aid only: not guaranteed and not subject to production testing.
32
MT8930C
Data Sheet
AC Electrical Characteristics† - ST-BUS Timing NT Mode (Ref. Figure 22)
Characteristics
Sym
Min
Typ‡
244
Max
Units
1
F0b input pulse width
tFPW
122
2
Frame pulse (F0b) set-up time
tFPS
35
ns
3
Frame pulse (F0b) hold time
tFPH
50
ns
4
C4b input clock period
tP4o
244
ns
5
C4b pulse width High or Low
tC4W
122
ns
6
C4b transition time
tC4T
20
ns
7
F0od delay
tDFD
8
F0od pulse width
tDFW
9
Serial input set-up time
tSIS
70
ns
10
Serial input hold time
tSIH
0
ns
11
Serial output delay
tSOD
12
HALF input setup time
tHAS
0
ns
13
HALF input hold time
tHAH
200
ns
20
Test Conditions
ns
87
244
ns
40 pF Load
ns
160
320
ns
ns
50 pF load
50 pF load (HDLC connected
to ST-BUS)
† Timing is over recommended temperature & power supply voltages
‡ Typical figures are at 25°C and are for design aid only: not guaranteed and not subject to production testing.
ST-BUS Bit Cell
tFPW
F0b
VIH
VIL
tFPS
C4b
DSTi
tC4W
VIH
VIL
tC4T
F0od
tP4o
tFPH
tDFD
tC4W
VOH
VOL
tSIS
tSIH
tDFW
VIH
VIL
tSOD
DSTo
VOH
VOL
tHAS
HALF
tHAH
VIH
VIL
Figure 22 - ST-BUS Timing NT Mode
33
MT8930C
Data Sheet
AC Electrical Characteristics† - ST-BUS Timing TE Mode (Ref. Figure 23)
Characteristics
Sym
Min
Typ‡
1
F0b output pulse width
tFPW
244
2
C4b to (F0b) delay
tCFD
10
3
C4b to (F0b) hold time
tCFH
10
4
C4b output clock period
tP4o
5
C4b pulse width High or Low
tC4W
6
C4b transition time
7
Max
Units
Test Conditions
ns
50 pF load
50
ns
50 pF load
50
ns
50 pF load
244
ns
50 pF load
122
ns
50 pF load (activated state)
tC4T
20
ns
50 pF load
F0od delay
tDFD
10
8
F0od pulse width
tDFW
220
9
Serial input setup time
tSIS
150
ns
10
Serial input hold time
tSIH
0
ns
11
Serial output delay
tSOD
125
ns
50 pF load
12
HALF output Delay
tHAD
150
ns
50 pF load
110
50
244
ns
ns
† Timing is over recommended temperature & power supply voltages
‡ Typical figures are at 25°C and are for design aid only: not guaranteed and not subject to production testing.
ST-BUS Bit Cell
tFPW
F0b
VOH
VOL
tCFH
tCFD
tP4o
tC4W
VOH
C4b
VOL
tC4W
F0od
DSTi
tC4T
VOH
VOL
tSIS
tSIH
VIH
VIL
tSOD
DSTo
VOH
VOL
tHAD
HALF
VOH
VOL
Figure 23 - ST-BUS Timing TE Mode
34
tDFD
tDFW
MT8930C
Data Sheet
AC Electrical Characteristics† - Intel Bus Interface Timing
Characteristics
Sym
Min
Typ‡
Max
(Ref. Figure 24 & 25)
Units
1
Chip select setup time
tCSS
10
ns
2
Chip select hold time
tCSH
25
ns
3
Address Latch pulse width
tALW
50
ns
4
Address setup time
tADS
20
ns
5
Address hold time
tADH
20
ns
6
Data setup time - Write
tDWS
35
ns
7
Data hold time - Write
tDHW
20
ns
8
Data output delay - Read
tDOD
9
Data hold time - Read
tDHR
25
10
Write pulse width
tWPW
60
ns
11
RD, WR delay
tRWD
60
ns
12
Read pulse width
tRPW
240
ns
13
Read setup time
tRDS
20
ns
Test Conditions
240
ns
50 pF load
90
ns
50 pF load
† Timing is over recommended temperature & power supply voltages
‡ Typical figures are at 25°C and are for design aid only: not guaranteed and not subject to production testing.
VIH
CS
VIL
tCSS
ALE
VIH
VIL
tADS
AD0-7
VIH
VIL
WR
VIH
VIL
RD
VIH
VIL
tCSH
tALW
tADH
tDHW
tRWD
Address
Data in
tWPW
tDWS
tRDS
Figure 24 - Intel Bus Interface Timing (Write Cycle)
CS
VIH
VIL
tCSS
ALE
VIH
tALW
VIL
tADS
AD0-7
VI/OH
tADH
Address
VI/OL
Data out
tRWD
RD
WR
VIH
VIL
VIH
tCSH
tDOD
tDHR
tRPW
tRDS
VIL
Figure 25 - Intel Bus Interface Timing (Read Cycle)
35
MT8930C
Data Sheet
AC Electrical Characteristics† - Motorola Bus Interface Timing (Ref. Figure 26)
Characteristics
Sym
Min
Typ‡
Max
Units
1
Chip select setup time
tCSS
10
ns
2
Chip select hold time
tCSH
10
ns
3
Address strobe pulse width
tASW
50
ns
4
Data strobe setup time
tDSS
20
ns
5
Data strobe hold
tDSH
20
ns
6
Data strobe pulse width
tDSW
100
240
ns
ns
7
Read/Write setup time
tRWS
40
ns
8
Read/Write hold time
tRWH
10
ns
9
Address setup time
tADS
20
ns
10
Address hold time
tADH
20
ns
11
Data setup time - Write
tDWS
35
ns
12
Data hold time - Write
tDHW
30
ns
13
Data output delay
tDOD
14
Data hold time - Read
tDHR
- Write
- Read
25
Test Conditions
240
ns
50 pF load
90
ns
50 pF load
† Characteristics are for clocked operation over the ranges of recommended operating temperature and supply voltage.
‡ Typical figures are at 25°C and are for design aid only: not guaranteed and not subject to production testing.
tCSH
tCSS
CS
VIH
VIL
tASW
AS
VIH
VIL
tDSS
DS
tDSH
VIH
VIL
tDSW
tRWS
R/W
VIH
VIL
tADS
AD0
-AD7
(Write)
VIH
VIL
VI/OH
VI/OL
tADH
tDWS
Address
tADS
AD0
-AD7
(Read)
tRWH
tADH
Data Input
tDHR
tDOD
Address
Figure 26 - Motorola Bus Interface Timing
36
tDHW
Data Output
MT8930C
Data Sheet
AC Electrical Characteristics† - Controllerless Mode Timing (Ref. Figure 27)
Typ‡
Characteristics
Sym
Min
Max
Units
Test Conditions
1
Cmode inputs setup time (TE Mode)
tCIS
120
ns
2
Cmode inputs setup time (NT Mode)
tCIS
120
ns
3
Cmode inputs hold time (TE Mode)
tCIH
120
ns
4
Cmode inputs hold time (NT Mode)
tCIH
120
ns
5
Cmode outputs delay (TE Mode)
tCOD
240
ns
50 pF load
6
Cmode outputs delay (NT Mode)
tCOD
240
ns
50 pF load
† Characteristics are for clocked operation over the ranges of recommended operating temperature and supply voltage.
‡ Typical figures are at 25°C and are for design aid only: not guaranteed and not subject to production testing.
F0b
VIH
VIL
C4b
VIH
VIL
tCIS
Inputs
VIH
VIL
Outputs
VOH
VOL
tCIH
tCOD
Controllerless Inputs include:
MFR (NT Mode)
MCH (TE Mode)
M/S (NT Mode)
AR
DR
Controllerless Outputs include:
IS0 & IS1
MFR (TE Mode)
MCH (NT Mode)
M/S (TE Mode)
Figure 27 - Controllerless Mode Timing
AC Electrical Characteristics† - IRQ, Rsti Timing (Ref. Figure 28)
Characteristics
Sym
1
Interrupt release delay
tIRD
2
Reset pulse width
tRSW
Min
Typ‡
Max
100
1
Units
Test Conditions
ns
µs
† Characteristics are for clocked operation over the ranges of recommended operating temperature and supply voltage.
‡ Typical figures are at 25°C and are for design aid only: not guaranteed and not subject to production testing.
DS/RD
VIH
VIL
tIRD
IRQ
VOH
VOL
tRSW
VIH
Rsti
VIL
Figure 28 - INT & Rsti Timing
37
MT8930C
Notes:
38
Data Sheet
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