Table of Contents

Contents

Page

2

Lucent Technologies Inc.

Data Sheet

April 1997

T7121 HDLC Interface for ISDN (HIFI-64)

Features ................................................................................................................................................................... 1

Description................................................................................................................................................................ 1

Pin Information ......................................................................................................................................................... 4

Functional Description .............................................................................................................................................. 8

Microprocessor Bus Interface ................................................................................................................................ 8

Addressing .......................................................................................................................................................... 8

Interrupts ............................................................................................................................................................. 8

Resets ................................................................................................................................................................. 9

FIFO Memory Buffers ............................................................................................................................................ 9

Transmit FIFO ..................................................................................................................................................... 9

Receive FIFO .................................................................................................................................................... 10

Block Move........................................................................................................................................................ 10

Serial Link Interface .......................................................................................................................................... 10

Enabling the Transmitter and Receiver ............................................................................................................. 10

Time-Slot Feature ............................................................................................................................................. 13

Transmission During Unassigned Time Slots ................................................................................................... 14

Bit Order During Transmission .......................................................................................................................... 14

Bit Masking........................................................................................................................................................ 16

SLD and IOM2 Examples.................................................................................................................................. 19

HDLC Operation .................................................................................................................................................. 19

Zero-Bit Insertion/Deletion (Bit Stuffing/Destuffing) .......................................................................................... 19

Transmitter FIFO ............................................................................................................................................... 21

Sending 1-Byte Frames .................................................................................................................................... 21

Transmitter Underrun ........................................................................................................................................ 21

Using the Transmitter Status and Fill Level ...................................................................................................... 21

Receiver FIFO ................................................................................................................................................... 21

Receiver Overrun .............................................................................................................................................. 23

Operational Note (T7121-EL, T7121-PL, T7121-EL2, and T7121-PL2) ............................................................ 23

Transparent Mode................................................................................................................................................ 24

Diagnostic Modes ................................................................................................................................................ 25

Loopbacks ......................................................................................................................................................... 25

3-State Mode..................................................................................................................................................... 28

Other ................................................................................................................................................................. 28

Powerdown Mode ................................................................................................................................................ 28

Registers.............................................................................................................................................................. 28

Absolute Maximum Ratings.................................................................................................................................... 45

Electrical Characteristics ........................................................................................................................................ 45

Clock Characteristics.............................................................................................................................................. 46

Timing Characteristics ............................................................................................................................................ 46

TDM Frame Timing Diagrams.............................................................................................................................. 46

Multiplexed Address and Data ............................................................................................................................. 51

Separate Address and Data................................................................................................................................. 53

Concentration Highway........................................................................................................................................ 55

Handling Precautions ............................................................................................................................................. 59

Outline Diagrams.................................................................................................................................................... 60

28-Pin, Plastic DIP ............................................................................................................................................... 60

28-Pin, Plastic SOJ, Surface Mounting................................................................................................................ 61

Ordering Information............................................................................................................................................... 62

Appendix................................................................................................................................................................. 63

Transparent Mode................................................................................................................................................ 63

HDLC Mode ......................................................................................................................................................... 63

General Features ................................................................................................................................................. 64

Power and Ground............................................................................................................................................... 66