
DS3161/DS3162/DS3163/DS3164
10.15 BERT
10.15.1 General Description
The BERT is a software-programmable test-pattern generator and monitor capable of meeting most error
performance requirements for digital transmission equipment. It will generate and synchronize to pseudo-random
patterns with a generation polynomial of the form x
n + xy + 1, where n and y can take on values from 1 to 32 and to
repetitive patterns of any length up to 32 bits.
The transmit direction generates the programmable test pattern, and inserts the test pattern payload into the data
stream.
The receive direction extracts the test pattern payload from the receive data stream, and monitors the test pattern
payload for the programmable test pattern. See
Figure 10-52 for the location of the BERT Block within the DS316x
devices.
Figure 10-52. BERT Block Diagram
IEEE P1149.1
JTAG Test
Access Port
Microprocessor
Interface
HDLC
FEAC
LLB
DLB
DS3 / E3
Transmit
Formatter
DS3 / E3
Receive
Framer
Trail
Trace
Buffer
Tx Cell
Processor
Tx
FIFO
System
Inter
face
Rx
Cell
Processor
Rx
FIFO
Tx Packet
Processor
SLB
Rx
Packet
Processor
TAIS
TUA1
TX
FRAC/
PLCP
RX FRAC/
PLCP
Clock
Rate
Adapter
TX BERT
RX BERT
PLB
ALB
UA1
GEN
B3ZS/
HDB3
Encoder
B3ZS/
HDB3
Decoder
10.15.2 Features
Programmable PRBS pattern – The Pseudo Random Bit Sequence (PRBS) polynomial (x
n + xy + 1) and seed
are programmable (length n = 1 to 32, tap y = 1 to n - 1, and seed = 0 to 2
n - 1).
Programmable repetitive pattern – The repetitive pattern length and pattern are programmable (the length n
= 1 to 32 and pattern = 0 to 2
n - 1).
24-bit error count and 32-bit bit count registers
Programmable bit error insertion – Errors can be inserted individually, on a pin transition, or at a specific
rate. The rate 1/10
n is programmable (n = 1 to 7).
Pattern synchronization at a 10
-3 BER – Pattern synchronization will be achieved even in the presence of a
random Bit Error Rate (BER) of 10
-3.
10.15.3 Configuration and Monitoring
Set PORT.CR1.BENA = 1 to enable the BERT.
The following tables show how to configure the on-board BERT to send and receive common patterns. The BERT
must be enabled before the pattern is loaded for the pattern load operation to take affect.