MSAN-141 Zarlink Semiconductor, Inc., MSAN-141 Datasheet - Page 7

• Manufacturer Part Number: MSAN-141
• Description: Implementation Details of the MT8930B-31B S-T Interface
• Manufacturer: Zarlink Semiconductor, Inc.

Application Note
Note
2.3.1
In the NT mode, asserting the Activation Request
(AR=1) bit will result in the transmission of the
INFO2 signal after the first occurrence of the system
frame pulse (F0i).
Request bit is not asserted
remote terminal will synchronize to INFO2 and
respond with INFO3. If the TE fails to synchronize to
the
determined by the user, the DR bit of the NT should
be set to 0 in order to respond with INFO0.
In the TE mode, AR=1 established from the
management entity, will result in the transmission of
the INFO1 signal after the first occurrence of the
system frame pulse (F0i).
of the loop, the Network Terminator will detect the
presence of Bus Activity (BA) and respond with
INFO2. (Note that the NT need not synchronize to
the incoming INFO1 signal.) This will allow the
activation of the line even if a collision occurred
during multiple INFO1 signals. If the NT does not
respond to the INFO1 before a software defined
timeout period (30 seconds worst case value), the
DR on the TE should be set in order to return to
sending INFO0.
When the NT responds to INFO1 with the INFO2
signal, the TEs will synchronize to the line signal and
respond with INFO3. At this point, the activation
state machine responds in the same way as though
the NT had initiated the activation.
During fault conditions, the state machine responds
as follows. If the NT loses sync with the incoming
data signal, it will return to sending INFO2. If the TE
loses synchronization with the incoming data, it
immediately stops sending INFO3 and sends INFO0.
The progression through the state machine can be
monitored using the binary encoded state sequence
for the respective mode of operation.
(1)
incoming
:
State Machine
For MT8930B, the frequency of the INFO1 signal may deviate by up to 50% of the nominal frequency if pin CK is connected
to ground as opposed to a 4.096 MHz clock.
TE
TE
TE
TE
TE
signal
As long as the Deactivation
after
Regular Frame with B,D, D-echo bits. A-bits set to binary one.
Regular Frame with B,D, D-echo and A-bit set to binary zero
If DR =0 on the NT side
Synchronized Frame with data on B and D-channels
(DR=0) on the TE, the
Positive zero, negative zero and six ones
a
timeout
Idle Line : All 1’s
Figure 5 - INFO Signals
period
In the NT mode, the binary encoded states (see
Table 2) are as follows:
When NT is in a deactivated state it is receiving and
transmitting the INFO0 signal. In pending activation
state the NT transmits the INFO2 signal while trying
to sync to INFO3. This state is only active if the
DR=0. In activated state the device is synchronized
to the remote TEs. This implies that it is transmitting
INFO4 while receiving INFO3. This state can only be
entered if the DR=0. If the DR =1, the state machine
will enter the pending deactivation state (if not
already in the deactivated state). This implies that
the NT will be transmitting INFO0 while receiving
INFO3 until the TE can recognize the DR. The
device will remain in this state until it receives INFO0
from the TE or the 32 ms timer expires. If after 32
msec., the TE has not responded to the DR the NT
will go into the deactivation state. The NT must enter
the deactivated state before activation can be
reinitiated.
Note:
Deact. Req.
Rcv. INFO0
Rcv. INFO1
Rcv. INFO3
INFO Sent
IS0
Lost Sync
T2 Expiry
Act. Req.
0
0
1
1
(1)
--
/
T2
State
= No change
= Not applicable
= Start Timer 2
IS1
0
1
0
1
Table 2. NT State Machine
- deactivated (G1)
- pending deactivation (G4)
- pending activation (G2)
- activated (G3)
G1
G2
G2
I0
--
--
/
/
/
NT
NT
NT
NT
NT
T2;G4 T2;G4
G2
G3
I2
--
--
--
/
/
MSAN-141
INFO0
INFO1
INFO2
INFO3
INFO4
G3
G2
G2
I4
--
--
/
/
G4
G2
G1
G1
I0
--
--
--
/
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