MT8931CP Zarlink Semiconductor, MT8931CP Datasheet - Page 8

• Manufacturer Part Number: MT8931CP
• Description: Description = 4 Wire Full-duplex 2B+D (192Kb/s) Data Format Isdn S And T Subscriber Network Interface Circuit ;; Package Type = Pdip ;; No. Of Pins = 28
• Manufacturer: Zarlink Semiconductor

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
deactivates the SNIC in response to line activity or
external command.
hardware driven and need not be initialized by the
microprocessor. The state diagram for initialization
is shown in Figure 7.
8
Info0
Info2
Info4
state
TE State Activation Diagram
NT State Activation Diagram
Signals from NT to TE
No Signal
Valid frame structure with
all B, D, D-echo and A bits
set to ‘0’
Valid frame with data in B,
D, D-echo channels. Bit A is
set to 1.
activation
Deactivated
send Info0
Activation
The controller is completely
send Info2
Pending
controller
DR = 1
Figure 7 - Link Activation Protocol, State Diagram
DR = 1
Sync = 1
AR = 1
BA = 1
BA = 0
Sync = 0
AR = 1
Info0
Info1
Info3
activates
No Signal
Continuous Signal of +‘0’, -‘0’
and six ‘1’s
Valid frame with data in B & D
Bits
Activation Request
Signals from TE to NT
send Info1 if BA = 0
send Info0 if BA = 1
Deactivated
send Info3
Activated
send Info4
send Info0
Activated
Sync = 1
BA = 0
DR = 1
or
DR = 1
AR = 1
(1)
The protocol used by the state activation controller is
defined as follows:
1) In the deactivated state, neither the NT nor TE
2) If the TE wants to initiate activation, it must begin
3) Once the NT has detected Info1, it begins to
assert a signal on the line (Info0).
transmitting a continuous signal consisting of a
positive zero, a negative zero followed by six
ones (Info1).
transmit Info2 which consists of an S-Bus frame
Sync = 1
A = 1 &
BA =0
Sync = 0
Time out
DR = 1
Sync = 1
Where: BA
Note 1: signal is not timebase locked to NT.
Note 2: Sync/BA bit of the Status Register
send Info3 if Sync = 1
send Info0 if Sync = 0
Deactivation
Send Info0
A = 0
Pending
Synchronized
DR = Deactivation Request
AR = Activation Request
Sync
A = Activation bit
Time out = 32 ms Timer Signal
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.
(2)
(2)
= Bus Activity
= Frame Sync Signal
Data Sheet