Altera POS-PHY Level 4 IP Core User Manual

Page 35

Chapter 3: Parameter Settings

3–15

Protocol Parameters

December 2014

Altera Corporation

POS-PHY Level 4 IP Core User Guide

For the Training pattern repetition value, the training sequence includes one IDLE
word, plus ALPHA(a) × 20 training words. ALPHA is a user-selectable option (0 to 255).
Zero (0) is equal to 256 training pattern repetitions.

The training sequence includes one IDLE control word, plus a × 20 words. The twenty
words are separated into ten consecutive tdat words of 16’h0FFF with tctl of 1’b1,
followed by ten consecutive tdat words of 16’hF000 with tctl of 1’b0.

For the Status sync good and Status sync bad threshold values, two 4-bit inputs,
good_level

(ctl_ts_sync_good_theshold) and bad_level

(ctl_ts_sync_bad_theshold), are associated with the stat_ts_sync signal.

The stat_ts_sync signal is asserted high when a good_level number of consecutive
status frames are received without frame or DIP-2 errors. The stat_ts_sync signal is
deasserted when a bad_level number of DIP-2 errors or frame errors have been
received since the last error-free frame.

The FIFO buffer threshold high (FTH) for transmitter variations controls when the
aN_atxdav

signal is asserted and deasserted for the write side of the FIFO buffer. The

aN_atxdav

signal indicates when there is room available to write new data into the

FIFO buffer, and is asserted whenever the remaining space in the buffer is greater than
the FTH value.

This threshold is defined in terms of bytes, with a valid range from N to buffer size
bytes, in N-byte increments, where:

■

N = 4 or 8 bytes for 32-bit data path variations

■

N = 8 or 16 bytes for 64-bit data path variations

■

N = 16 or 32 bytes for 128-bit data path variations

The N-byte values depend on the Atlantic interface width and on the Lite transmitter
setting.

Table 3–6

shows the N-byte values, based on the transmitter's settings.

Although the parameter editor allows you to set FTH values as low as one FIFO
buffer element (translated to bytes), a minimum FTH value is used internally. And,
depending on the core's configuration, up to four FIFO buffer locations are unusable.
For the exact minimum FTH value and number of unusable locations, refer to the
parameter editor message that appears while configuring the core.

Table 3–6. N-Byte Values

Datapath Width

Atlantic Interface

Width

Lite Transmitter

N Bytes (FTH

Increment)

—

Off

128

On or off

128

Off