MT90221AL datasheet(22/114 Pages) MITEL

22 / 114 page

MT90221

The SCCI ﬁeld is incremented by one for each

transfer command performed

which includes a

change in at least one byte of the ICP cell.

2.4.8

IMA Frame Programmable Interrupt

An optional interrupt is provided at the end of an IMA

frame to simplify software implemented changes in

the Group Control and Status ﬁeld. This interrupt can

be enabled on an as required and per group basis to

implement a frame counter. The TX ICP Cell

Handler and TX ICP Interrupt Enable registers are

used for the transfer ready and frame interrupt.

2.4.9

Filler Cell Definition

The content of the Filler cell is pre-initialized and

conforms with the IMA Speciﬁcation.

2.4.10 TX IMA Group Start-Up

Initialize the TX IMA Group start-up as follows:

(Note:

The

startup

procedure

below

given

indicating the most important steps. A more detailed

and complete sequence can be found in the

MT90220/221 Programmer’s Manual and example

code)

•

Conﬁgure the TX PCM port(s) by writing to the

TX PCM Link Control register 1 and 2.

•

Write the value of M, the Timing Mode and the

reference link number to the TX Group Control

number to be initialized.

•

Write the Link ID (LID is between 0-31) to TX

Link ID registers for each link to be used in the

IMA Group. LID should not be changed when a

group is operational. Ensure each link that is

part of an IMA group has a unique LID (note

that the MT90221 does not verify LIDs).

•

Write the ICP Cell Offset value to TX ICP Cell

Offset registers. This value depends on the

value of M. Typically, the reference link will have

a delay of 0 cells in the IMA Frame and the ICP

cell in each other link will be evenly spaced in a

multiple of M/N cells (where M is deﬁned in the

IMA speciﬁcation and N is the number of links).

The offset value for an operational group should

not be changed.

•

Write to the TX Link Control registers to put

the link(s) in IMA mode and to enable the

transfer of ATM User Cells when required.

2.4.11 TX Link Addition

The MT90221 supports software controlled link

addition to the existing IMA group. Link addition is

used to increase the available bandwidth. The TX

PCM Link Control register 1 and 2, the TX Link ID

and TX ICP Cell Offset registers are initialized ﬁrst

with the proper IMA Group information. The link is

assigned to a TX IMA group by writing to the lower 2

bits of the TX Link Control register. The bit 3, 1 and

0 of the Test 2 register have to be written with the

proper value. The link is then conﬁgured in IMA

mode by writing to the bit 2 of the TX Link Control

monitored to detect when the link is reported in IMA

mode. When the link is in IMA mode, then the bit 3, 1

and 0 of the Test 2 register are reset to 0. TX Link

Control register bit 6 determines when ATM User

cells can be sent. Note that the Test 2 register

cannot be used as a read/modify/write register. The

values that are written and the values that are read

are independant. Note also that the bit 6 of the Test

2 register shulld always be set to 1.

2.4.12 TX Link Deletion

There are two reasons to remove a link: the required

bandwidth decreases or a link becomes faulty. The

MT90221 supports link deactivation under software

control.

A link stops transmitting User cells when bit 6 of the

TX Link Control register is set to 0. Filler and ICP

cells will still be sent on the link. The link is removed

from an IMA group by ﬁrst setting the bit 2 of the TX

Link Control register to 1 while keeping the original

IMA group number. The IMA group number can be

changed only when the link is reported in UNI mode

as reported in the TX IMA Mode Status register. It

then can be assigned to another IMA group.

When removing the last link of a TX IMA group, the

TX Utopia FIFO has to be empty. This can easily be

done by ﬁrst disabling the source of ATM cells (ATM

Utopia contoller), then disabling the TX Utopia Port

using the UTOPIA Input Link or Group PHY Enable

registers while still keeping the “Send User Cell” bit

of the TX Link Control register set to 1. After a period

of time corresponding to “n” IDCR clock tick has

elapsed, then the above procedure can be applied to

assign the link in UNI mode.” The value of “n”

depends on the size of the TX Utopia FIFO as

deﬁned in the TX FIFO Length Deﬁnition registers.

The level of the TX Utopia FIFO can be monitored

using TX Utopia FIFO Level register. Then, the

above procedure can be applied to assign the link in

UNI mode.

2.5

ATM Transmit Path in UNI Mode

A maximum of four independent T1/E1 interfaces

can be selected in UNI mode. Figure 4 gives a

functional block diagram of the transmitter in UNI

mode.

MT90221AL Datasheet(PDF) 22 Page - Mitel Networks Corporation

MT90221AL Datasheet(HTML) 22 Page - Mitel Networks Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL