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____________________________________________________ DS34T101, DS34T102, DS34T104, DS34T108
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The BERT function must be enabled and configured for each port (see the
TXPC and
RXPC registers). The BERT
can be assigned to any combination of 64kbps channels within the E1/T1 signal using the bits in the
TBPCS and
RBPCS registers. Individual bit positions within the channels can be suppressed (i.e. not used for patterns) using
The following tables show how to configure the BERT to send and Rx common telecom patterns.
Table 10-61. Pseudorandom Pattern Generation
PATTERN TYPE
PTF[4:0]
(hex)
PLF[4:0]
(hex)
PTS
QRSS
TPIC,
RPIC
2
9-1 O.153 (511 type)
04
08
0
0x0408
0xFFFF
0
2
11-1 O.152 and O.153
(2047 type)
08
0A
0
0x080A
0xFFFF
0
2
15-1 O.151
0D
0E
0
0x0D0E
0xFFFF
1
2
20-1 O.153
10
13
0
0x1013
0xFFFF
0
2
20-1 O.151 QRSS
02
13
0
1
0x0253
0xFFFF
0
2
23-1 O.151
11
16
0
0x1116
0xFFFF
1
Table 10-62. Repetitive Pattern Generation
PATTERN TYPE
PTF[4:0]
(hex)
PLF[4:0]
(hex)
PTS
QRSS
all 1s
NA
00
1
0
0x0020
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
After configuring these bits, the pattern must be loaded into the BERT. This is accomplished via a zero-to-one
Monitoring the BERT requires reading the BSR Register which contains the Bit Error Count (BEC) bit and the Out
of Synchronization (OOS) bit. The BEC bit is set when the bit error counter is one or more. The OOS is set when
the Rx pattern generator is not synchronized to the incoming pattern, which occurs when it receives a minimum of
6 bit errors within a 64-bit window. The Rx BERT Bit Count Registers
(RBCR) and the Rx BERT Bit Error Count
Registers
(RBECR) are updated upon the zero-to-one transition of a performance monitor update signal (either
BCR.LPMU or
GCR2.BRPMU as specified by
BCR.PMUM). This signal updates the registers with the values of the
counters since the last update and resets the counters.
10.14.4 BERT Receive Pattern Detection
The Rx BERT synchronizes the Rx pattern generator to the incoming pattern. The Rx pattern generator is a 32-bit
shift register that shifts data from the least significant bit (LSB, bit 1) to the most significant bit (MSB, bit 32). The
input to bit 1 is the feedback. For a PRBS pattern (generating polynomial x
n + xy + 1), the feedback is an XOR of bit
n and bit y. For a repetitive pattern (length n), the feedback is bit n. The values for n and y are individually