Datasheet

DS26303: 3.3V, T1/E1/J1, Short-Haul, Octal Line Interface Unit
68 of 101
6.9 BERT
The BERT is a software-programmable test-pattern generator and monitor capable of meeting most error-
performance requirements for digital transmission equipment. It generates and synchronizes to pseudorandom
patterns with a generation polynomial of the form x
n
+ x
y
+ 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. The features include:
• Programmable PRBS pattern. The pseudorandom bit sequence (PRBS) polynomial (x
n
+ x
y
+ 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 is achieved even in the presence of a
random bit-error rate (BER) of 10
-3
.
6.9.1 Configuration and Monitoring
Set BTCR:BERTE = 1 to enable the BERT. The following tables show how to configure the on-board BERT to send
and receive common patterns.
Table 6-10. Pseudorandom Pattern Generation
BPCR REGISTER BERT.CR
PATTERN TYPE
PTF[4:0]
(hex)
PLF[4:0]
(hex)
PTS QRSS
BERT.
PCR
BERT.
SPR2
BERT.
SPR1
TPIC,
RPIC
2
9
-1 O.153 (511 type) 04 08 0 0 0x0408 0xFFFF 0xFFFF 0
2
11
-1 O.152 and O.153
(2047 type)
08 0A 0 0 0x080A 0xFFFF 0xFFFF 0
2
15
-1 O.151 0D 0E 0 0 0x0D0E 0xFFFF 0xFFFF 1
2
20
-1 O.153 10 13 0 0 0x1013 0xFFFF 0xFFFF 0
2
20
-1 O.151 QRSS 02 13 0 1 0x0253 0xFFFF 0xFFFF 0
2
23
-1 O.151 11 16 0 0 0x1116 0xFFFF 0xFFFF 1
Table 6-11. Repetitive Pattern Generation
BPCR REGISTER
PATTERN TYPE
PTF[4:0]
(hex)
PLF[4:0]
(hex)
PTS QRSS
BERT.
PCR
BERT.
SPR2
BERT.
SPR1
All 1s NA 00 1 0 0x0020 0xFFFF 0xFFFF
All 0s NA 00 1 0 0x0020 0xFFFF 0xFFFE
Alternating 1s and 0s NA 01 1 0 0x0021 0xFFFF 0xFFFE
Double alternating and 0s NA 03 1 0 0x0023 0xFFFF 0xFFFC
3 in 24 NA 17 1 0 0x0037 0xFF20 0x0022
1 in 16 NA 0F 1 0 0x002F 0xFFFF 0x0001
1 in 8 NA 07 1 0 0x0027 0xFFFF 0xFF01
1 in 4 NA 03 1 0 0x0023 0xFFFF 0xFFF1