~ National ~ Semiconductor - Al Kossow's Bitsavers

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NSC Solutions: Systems Level
Building an ISDN TE or TA
Shown below is a typical application of the chip set in a
Basic Access TE, which offers one voice channel and an
RS232 interface to support an external terminal. The
TP3420 'S' Interface Device ensures that the system is
compatible with any'S' or 'T' standard jack socket and provides
the multiplexing for the other devices operating in the
'B' and 'D' channels. All timing for the TE is derived by the
TP3420 from the received line signal. In a typical application,
LAPD signalling in the 'D' channel is provided via
TP3054/57
COMBO
HDLC #1 on the HPC16400. HDLC #2 is working in conjunction
with the UART to provide an X.25 or LAPD packetmode
in a 'B' channel at 64 kb/s. Terminal Adaption of both
the data and the terminal handshaking signals is performed
by the HPC16400 via the UART and HDLC controller #2,
which can use either of the 'B' channels. DMI modes 2 and
3 (for a single channel) can be supported using this method,
with the necessary data buffers set up in internal RAM. The
other 'B' channel is occupied by the TP305417 PCM COM­
BO providing the digitized voice channel.
ROM +
PACKET
RAM
TP3420
'SID'
II[
lie
1
'5'
INTERFACE
TLIX/0008-4
PBX 2 Wire Terminals
The following example shows how simple it is to convert an
'S' Interface terminal, which requires 2 twisted pairs, to a
terminal using only a single pair by replacing the
TP3420 SID with a TP3401 DASL. The clean partitioning of
device functions makes this possible with no other changes
to the design.
TP3054/57
COMBO
TP3401
OASL
lie
1
MICROWIRE
'U'
INTERFACE (:S2 km)
ROM +
PACKET
RAM
TLIX/0008-5
3-6