VSC7440 datasheet(256/444 Pages) MICROSEMI

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Functional Descriptions

VMDS-10492 VSC7440 Datasheet Revision 4.2

239

The following table lists the registers associated with TTI timer tickers.

The following table lists the registers associated with configuring parameters for each of the 2K entries in

the TTI table.

Table 164 •

TTI Timer Ticks Registers Overview

Field

Description

Replication

TTI_TICK_LEN_0_3

TTI_TICK_LEN_4_7

LEN0 -

LEN7

Length of timer ticks.

The length of each of the eight timer ticks is

specified as multiples of the length of the

preceding timer tick (that is, <tick_idx>-1). Timer 0

is the shortest timer tick, and timer tick 7 is the

longest.

Tick 0 is specified in multiple of TTI_TICK_BASE

(default 52 µs).

Default configuration:

tick_idx

tick_len

Tick_Period

52 µs

(1 × 52 µs)

416µs

(8×52 µs)

3.3 ms

(8 × 416 µs)

10 ms

(3 × 3.3 ms)

100 ms

(10 × 10 ms)

1 second

(10 × 100 ms)

10 seconds (10 × 1 sec)

1 minute

(6 × 10 sec)

TTI_TICK_BASE

BASE_LEN Length of TTI base tick in system clock cycles.

Table 165 •

TTI Parameters (2048 entries)

Field

Description

Replication

TTI_PORT_QU

PORT_NUM

Port number on which injection queue transmits.

Per TTI

TTI_TIMER

TICK_IDX

Which of the eight timer ticks is used by the timer controlling the

injection of this frame.

Per TTI

TTI_TIMER

JITTER_MODE Enables jitter for the number of timer ticks between each

injection of this frame.

0: No jitter.

1: Timer is set to a random value in the range [TIMER_LEN*0.75;

TIMER_LEN].

2: Timer is set to a random value in the range [TIMER_LEN*0.50;

TIMER_LEN].

3: Timer is set to a random value in the range [1;TIMER_LEN].

Per TTI

TTI_TIMER

TIMER_LEN

Number of timer ticks between each injection of this frame.

0: Disables timer.

0xff: Injects frame next time the entry is serviced. After servicing,

hardware sets TIMER_LEN to 0. This is intended to be used

during removal of frame from buffer memory. See Removing

Injection Frames, page 245.

Per TTI

TTI_FRM

FRM_PTR

Points to the frame (in frame table), which the TTI injects.

Per TTI

TTI_TICKS

TICK_CNT

Number of ticks until next injection.

Should be set to a random value in the range 1-TIMER_LEN

before starting TTI.

Per TTI

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