MT90221 Zarlink Semiconductor, MT90221 Datasheet - Page 33

• Manufacturer Part Number: MT90221
• Description: Quad Inverse Multiplexing For Atm (IMA) Device With Flexible Ima And Uni Mode
• Manufacturer: Zarlink Semiconductor

MT90221
a. "Grouped" corresponds to the use of the first 23 or 24 channels (timeslots) from the 32 timeslots available in a frame.
b. "Spaced" corresponds to the use of 3 channels every 4 channels (timeslots) from the 32 timeslots available in a frame.
c. "Fixed" corresponds to the use of channels 1-15 and 17-31 leaving channels (timeslots) 0 and 16 not used.
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When the TXCK and TXSYNC signals are outputs,
the source for the TXCLK is software selectable from
any of the four RXCK inputs or any of the four
external REFCKs. The TXSYNC signal is generated
from the TXCK and is independent from (not aligned
with) the RXSYNC or other TXSYNC signals.
4.2
There are 8 major modes of operation for the PCM
interface. The only difference between modes 1 to 4
and modes 5 to 8 is in the direction of the TXCK and
TXSYNC signals. In the PCM modes 5 to 8, the
direction is the opposite of what is defined in modes
1 to 4. The direction of the TXCK and TXSYNC
signals is defined by the bit 4 in the TX PCM Link
Control Register #2 and the PCM mode is defined
in the TX PCM Link Control Register #1
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24
T1 ISDN
(23 channels)
T1 Clear Channel
(24 channels)
E1 (30 channels)
Mode 1
Mode 2
Mode 3
Mode 4
Mode 5
Mode 6
Mode 7
Mode 8
Clock Frequency
PCM Major Modes
generating a TXSYNC pulse on every PCM
frame when defined as output
assigning any TX or RX link to any IMA Group
Mode 1: Generic PCM interface for T1
applications, TXCK and TXSYNC outputs
Mode 2: ST-BUS interface for T1 applications,
TXCK and TXSYNC inputs
Mode 3: Generic PCM interface for E1
applications, TXCK and TXSYNC outputs
PCM Mode
PCM System Interface Modes
Mapping
Grouped
Reg 1 bit 6
Yes
Yes
TX PCM Control Registers 1 & 2
--
0
0
1
1
0
0
1
1
a
Table 7 - PCM Clock and Mapping Options
4.096 MHz
ST-BUS
Spaced
Reg 1 bit 5
Yes
Yes
--
0
1
0
1
0
1
0
1
b
Table 6 - PCM Modes
Fixed
Yes
Reg 2 bit 4
--
--
c
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T1 with ISDN services operation is available in PCM
Modes 1, 2, 5 and 6. Channel 24 is not used to carry
the ATM cells and is reserved for signaling. In this
case, 23 channels are used to carry the ATM cells
over the links and all the links in the IMA Group must
have the same option selected. The signaling
channel is always channel 24 in the T1 frame and its
position will vary with the PCM frame length.
In PCM Mode 1 and 5, the clock can be either 1.544
or 2.048 MHz. If a 2.048 MHz clock is selected, the
mapping of the 24 channels can be either grouped
(the first 24 consecutive timeslots starting with the
Frame Pulse) or spaced (3 of every 4 timeslots,
starting with the second timeslot of the 32 timeslot
frame).
0
0
0
0
1
1
1
1
Mode 4: ST-BUS interface for E1 applications,
TXCK and TXSYNC inputs
Mode 5: Generic PCM interface for T1
applications, TXCK and TXSYNC inputs
Mode 6: ST-BUS interface for T1 applications,
TXCK and TXSYNC outputs
Mode 7: Generic PCM interface for E1
applications, TXCK and TXSYNC inputs
Mode 8: ST-BUS interface for E1 applications,
TXCK and TXSYNC outputs
1.544MHz
Fixed
Yes
Yes
--
E1/T1
E1
E1
E1
E1
T1
T1
T1
T1
Grouped
Yes
Yes
--
ST-BUS/
Generic
Generic
ST-BUS
Generic
ST-BUS
Generic
ST-BUS
Generic
ST-BUS
GENERIC
Description
2.048 MHz
Spaced
Yes
Yes
--
TXCK/TXSYNC
(Input/Output)
Output
Output
Output
Output
Input
Input
Input
Input
Fixed
Yes
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