MT90220
ST-BUS
Bit Cells
(DSTx0-7)
...
Channel 31 bit 0
Bit Cell
Channel 0 bit 7
Channel 0 bit 0
Channel 1 bit 7
Bit Cell
...
Unused or
High Impedance
Unused or
High Impedance
Serial Bit
Stream
...
...
...
...
TXSYNC
RXSYNC
TXCK
RXCK
...
...
...
...
ST-BUS
Bit Cells
(DSTx0-7)
Channel 15 bit 0
Bit Cell
Channel 16 bit 7
Channel 16 bit 0
Channel 17 bit 7
Bit Cell
Unused or
High Impedance
Unused or
High Impedance
Serial Bit
Stream
...
...
...
...
...
...
TXSYNC
RXSYNC
TXCK
RXCK
Figure 11 - PCM Mode 4 and 8: ST-BUS Interface for E1
E1 Time-Slots
-
1
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
10 11 12 13 14 15
10 11 12 13 14 15
Voice/Data Channels
(DSTi/o)
0
x
E1 Time-Slots
-
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Voice/Data Channels
(DSTi/o)
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
x
Table 10 - Channel Mapping from ST-BUS to E1
1, the TXCK and TXSYNC pins are outputs. In the
PCM Mode 5, the TXCK and TXSYNC pins are
defined as inputs.
of the PCM frame (i.e., the T1 framing bit) to perform
the G.804 recommended transmission convergence
function (see Figure 12). This frame bit is also
ignored on the receive side. The position of the
frame bit is indicated by the TXSYNC and RXSYNC
signals.
4.2.3.1 1.544 MHz Clock
In this sub-mode, (selected by clearing the bit 4 of
the TX PCM Control Register 1,) the serial PCM
Interface rate is equal to the line bit rate. When
selected to operate in this sub-mode, the interface
clock is 1.544 MHz and the DSTo and DSTi the data
lines transport only 24 time-slots plus the DS1
framing bit for a total of 193 bits per frame.
4.2.3.2 2.048 MHz Clock
In this sub-mode (selected by setting the bit 4 of the
TX PCM Control Register 1) the channel/timeslot
mapping for this mode is similar to the ST-BUS mode
for T1. The same PCM mapping schemes (grouped
or spaced) are supported. The TXCLK and RXCLK
are 2.048 MHz signal and the TXSYNC and
RXSYNC are a frame pulse of one full bit duration
that occurs at the beginning of the frame. The frame
rate is 8 KHz. The polarity of the TXCK, RXCK,
TXSYNC and RXSYNC and their active edge is
programmable using TX PCM Link Control register
number 1 and RX PCM Link Control register.
The frequency value for TXSYNC and RXSYNC is 8
kHz. The frequency for the TXCK and RXCK is 1.544
Mhz.
The edge of the RXCK and TXCK signals used to
sample incoming data and transmit the outgoing data
is fully programmable on a per link basis. This allows
the MT90220 to operate with the majority of available
off-the-shelf T1 framers.
4.2.4 Mode 3 and 7: Generic PCM Interface for E1
The channel/timeslot mapping in this mode is similar
to the ST-BUS mode for E1. The differences are:
When operating in the generic PCM system Interface
at 1.544 MHz, the MT90220 does not use the first bit
27
MITEL [ MITEL NETWORKS CORPORATION ]
