Visible to Intel only — GUID: rre1607357050678
Ixiasoft
Visible to Intel only — GUID: rre1607357050678
Ixiasoft
13.8.1. Reading the Default Traffic Generator Status
The traffic generator provides detailed failure information, as described below.
Pass-Not-Fail (PNF) bits
The width of the pnf_per_bit bus equals the data width on the Avalon Control interface. Each PNF bit represents the status of each data bit, as gathered from comparison between the data written to a particular address and the read response from the same address.
pnf_per_bit[x] is high provided that no write-read mismatches have occurred on bit x. PNF bits are persistent, meaning that once a bit is set low due to a data mismatch, it remains low until the next TG reset.
The PNF bits map to the control interface data bits in a 1:1 manner. To understand the mapping to data pins on the memory side, consider the example of a 32-bit DDR4, quarter-rate interface. This interface has a control data width of 256, where the following are true:
- pnf[0] maps to dq[0] for the first beat of the memory bus burst
- pnf[1] maps to dq[1] for the first beat of the memory bus burst
- ...
- pnf[31] maps to dq[31] for the first beat of the memory bus burst
- pnf[32] maps to dq[0] for the second beat of the memory bus burst
- ...
- pnf[64] maps to dq[0] for the third beat of the memory bus burst
- ...
- pnf[96] maps to dq[0] for the fourth beat of the memory bus burst
- ...
- pnf[128] maps to dq[0] for the fifth beat of the memory bus burst
- pnf[160] maps to dq[0] for the sixth beat of the memory bus burst
- ...
- pnf[192] maps to dq[0] for the seventh beat of the memory bus burst
- ...
- pnf[224] maps to dq[0] for the eighth beat of the memory bus burst
A similar mapping approach applies to any other supported interface memory bus width.
Information about First Observed Failure
The traffic generator has registers that store the address of the first data mismatch, the expected data, the read data, etcetera. These registers can be read through ISSPs or by adding them to a Signal Tap waveform. For a detailed description of all ISSPs that are present in the example design, refer to ISSPs Tab.