MT8971B/72B

9-114

CD port, the CDSTi and CDSTo pins are used. The

SINGL port option only exists in DN mode.

In MOD mode, DUAL port operation must be used

and the D, B1 and B2 channel designations no

longer exist. The selection of SLV or MAS will

determine which of the DNICs is using the externally

supplied clock and which is phase locking to the data

on the line. Due to jitter and end to end delay, one

end must be the master to generate all the timing for

the link and the other must extract the timing from

the receive data and synchronize itself to this timing

in order to recover the synchronous data. DUAL port

mode allows the user to use two separate serial

busses: the DV port for PCM/data (B channels) and

the CD port for control and signalling information (C

and D channels). In the SINGL port mode, all four

channels are concatenated into one serial stream

and input to the DNIC via the DV port. The order of

the C and D channels may be changed only in DN/

DUAL mode. The DNIC may be configured to

transfer the D-channel in channel 0 and the C-

channel in channel 16 or vice versa. One other

feature exists; ODE, where both the DV and CD

ports are tristated in order that no devices are

damaged due to excessive loading while all DNICs

are in a random state on power up in a daisy chain

arrangement.

Table 2. Mode Definitions

Table 3. Pin Configurations

Mode

Function

SLV

SLAVE

crystal is phase locked to it to provide clocks for the entire device and are output for the external

system to synchronize to.

MAS

MASTER

which must be frequency locked. The transmit data is synchronized to the system timing with the

receive data recovered by a clock extracted from the receive data and resynchronized to the system

timing.

DUAL

DUAL PORT

and the DV port transferring the B1& B2 channels.

SINGL

SINGLE PORT - The B1& B2, C and D channels are all transferred through the DV port. The CD

port is disabled and CDSTi should be pulled high.

MOD

MODEM

through the DV port at the baud rate selected. The C-channel is transferred through the CD port

also at the baud rate and is synchronized to the CLD output.

DN

DIGITAL NETWORK

2.048 Mbits/s and the line at 80 or 160 kbits/s configured according to the applicable ISDN

recommendation.

D-C

D BEFORE C-CHANNEL

C-D

C BEFORE D-CHANNEL

ODE

OUTPUT DATA ENABLE

impedance state. This is intended for power-up reset to avoid bus contention and possible damage

to the device during the initial random state in a daisy chain configuration of DNICs. In all the other

modes of operation DV and CD ports are enabled during the appropriate channel times.

Mode

#

F0/CLD

F0o/RCK

C4/TCK

Name

Input/Output

Name

Input/Output

Name

Input/Output

0F0

Input

F0o

Output

C4

Input

1CLD

Output

RCK

Output

TCK

Output

2F0

Input

F0o

Output

C4

Input

3F0

Input

F0o

Output

C4

Input

4F0

Output

F0o

Output

C4

Output

5CLD

Output

RCK

Output

TCK

Output

6F0

Output

F0o

Output

C4

Output

7F0

Input

F0o

Output

C4

Input