stlc5412 STMicroelectronics, stlc5412 Datasheet - Page 18

• Manufacturer Part Number: stlc5412
• Description: 2b1q U Interface Device Enhanced With Dect Mode
• Manufacturer: STMicroelectronics

STLC5412
GCI MODE
The GCI is a standard interface for the intercon-
nection of dedicated ISDN components in the dif-
ferent equipments of the subscriber loop :
In a Terminal, GCI interlinks the STLC5412, the
ISDN layer 2 (LAPD) controller and the voice/data
processing components as an audio-processor or
a Terminal Adaptor module.
In NT1-2, PABX subscriber line card, or central
office line card (LT), GCI interlinks the UID, the
ISDN Layer 2 (LAPD) controllers and eventually
the backplane where the channels are multi-
plexed.
In NT1, GCI interlinks SID-GCI and STLC5412,
via automode (NT1-auto). In Regenerators, GCI
links both STLC5412 UID in automode (NT-RR-
auto, LT-RR-auto). (See Fig. 4a)
Frame Structure
2B+D data and control interface is transferred in a
time-division multiplexed mode based on 8 kHz
frame structure and assigned to four octets per
frame and direction.(see fig.4b).
The 64 kbit/s channels B1 and B2 are conveyed
in the first two octets; the third octet (M: Monitor)
is used for transferring most of the control and
status registers; the fourth octet (SC: Signalling &
Control) contains the two D channel bits, the four
C/I (command/lndicate) bits controlling the activa-
tion/deactivation procedures, and the E & A bits
which support the handling of the Monitor chan-
nel.
Figure 4a: GCI configurations of the UID.
18/74
Figure 4a: GCI configurations of the UID
TERMINAL
SID-GCI
S
SID-GCI
PRIVA TE TERMINAL
OR NT1-2
NT1
NT1-AUTO
NT
U
U
LT-RR-AUTO
These four octets per frame serving one ISDN
subscribers line form a GCI Channel. One GCI
channel calls for a bit rate of 256 kbit/s.
In NT1-2s or subscriber Line Cards up to 8 GCI
channels may be carried in a frame of a GCI mul-
tiplex. The bit rate of a GCI multiplex may be from
256 kbit/s and up to 3088 kbit/s. Adjacent 4-octet
slots from the frame start are numbered 0 to 7.
The GCI channel takes the number of the slot it
occupies. Spare bits in the frame beyond 256 bits
from the frame start will be ignored by GCI com-
patible devices but may be used for other pur-
poses if required (see Fig.4c). GCI channel num-
ber is selected by biasing pins S0,S1,S2.
Physical Links
Four physical links are used in the GCI.
Transmitted data to the line: Bx
Received data from the line: Br
Data clock: BCLK
Frame Synchronization clock: FSa
GCI is always synchronized by frame and data
clocks derived by any master clock source.
A device used in NT mode can deliver clock
sources able to synchronize GCI, either directly,
or via a local Clock Generator synchronized on
the line by means of the SCLK 15.36 MHz output
clock. Frame clock and data clock could be inde-
pendent of the internal devices clocks. Logical
one on the Br output is the high impedance state
while logical zero is low voltage. For E and A bits,
active state is voltage Low while inactive state is
high impedance state.
REPETOR
NT-RR-AUTO
U
LINE TERMINATION
LT