3. RapidIO Lanes > Bit Error Rate Testing
CPS-1848 User Manual
84
June 2, 2014
Formal Status
This document is confidential and is subject to an NDA.
Integrated Device Technology
3.6
Bit Error Rate Testing
Bit Error Rate (BER) measurement is supported as part of the RapidIO protocol, as well as through the per-lane status
registers. For more information, see the
and the registers that follow. BER measurement when the
RapidIO protocol is active restricts the data patterns generated to valid 8b/10b codes.
The CPS-1848 has a Pseudo-Random Binary Sequence (PRBS) generator capability that supports testing based on random
bit sequences.
PRBS-based BER testing is performed on individual lanes. The programming model for PRBS testing consists of the following
registers:
•
– PRBS enable and pattern selection
•
Lane {0..47} PRBS Generator Seed Register
– PRBS pattern “seed” value
•
Lane {0..47} PRBS Error Counter Register
– Count of errors detected for PRBS (Revision C only)
Each Lane Level Block has a PRBS generator that is enabled by setting PRBS_EN and XMITPRBS to 1 in the
. The generator supports five user-selectable PRBS polynomials and three user-defined fixed patterns, as
described in the following sections.
3.6.1
PRBS Polynomials
The following polynomials are supported by the CPS-1848:
1. x
23
+x
18
+ 1 — For additional definition of the polynomial, see CCITT O.1S1/ITU-T O.150 section 5.6 [SONET].
2. x
31
+x
28
+ 1 — For additional definition of the polynomial, see ITU-T O.150 section 5.8 (and XAUI, IEEE Std. 802.3-2008).
3. x
10
+x
7
+ 1 — For additional definition of the polynomial, CCITT O.1S2/ITU-T O.192.
4. x
15
+x
14
+ 1
5. x
7
+x
6
+ 1
By default, the first value, also called as the seed, for all polynomials is all 1s. To change the seed used by the polynomial,
program the
Lane {0..47} PRBS Generator Seed Register
.
The Lane Level Block allows the PRBS seed to be changed by programming the
Lane {0..47} PRBS Generator Seed Register
.
Note that a value of all zeros produces indeterminate results. This register is used for programming the two 10-bit re-circulating
seeds. The first 10 bits of this register is used for one seed and the next 10 bits for the other.
3.6.2
User-Defined Patterns
In addition to random bit sequences, the CPS-1848 also supports patterns that are deterministic. There are three pattern
options. The pattern value is the least significant 10 bits (22–31) of the
Lane {0..47} PRBS Generator Seed Register
1. Send the pattern value continuously
2. Send the pattern value, followed by its inverse value, continuously
The CPS-1848 cannot check PRBS sequences; it can only generate PRBS sequences.
This caution is applicable to Revision A and B only.
When a PRBS polynomial is selected, a seed value of 0 is a programming error.
Only bits that are controlled by the polynomial are used when programming the seed value. For
example, if x
23
+x
18
+ 1 is the polynomial selected, only the least significant 24 bits (8–31) of the
{0..47} PRBS Generator Seed Register
are relevant.