Preliminary Information
MT90710
CORRECT SYNC
SET SYNC = LAST STATE
STATE 1
CORRECT SYNC
SET SYNC = FALSE
INCORRECT SYNC
SET SYNC = LAST STATE
STATE 2
INCORRECT SYNC
SET SYNC = TRUE
CORRECT SYNC
SET SYNC = TRUE
STATE 0
INCORRECT SYNC
SET SYNC = FALSE
STATE 3
INCORRECT SYNC
SET SYNC = FALSE
CORRECT SYNC
SET SYNC = TRUE
Figure 5 - State Diagram
approximately a 4 Hz rate when the far-end is out of
synchronization but the near-end is synchronized. If
the near-end is not synchronized this output is
inactive.
The open collector LLED output (pin 70) will cause
an LED, pulled up to +5 volts, to flash at
approximately a 4 Hz rate when the near-end is out
of synchronization.
Fiber to ST-BUS
When ST6MUX is enabled the STo6A and STo6B
output streams are comprised of the demultiplexed
information received from the fiber link. The received
data is duplicated on two channels since the ST-BUS
channels support twice the bandwidth of the data
from the incoming fiber link. See Table 2.
When ST6MUX is disabled the STi6B and STo6B
ports are not operational. The STi6A and STo6A
ports operate as clear 2.048 MHz links in the same
manner as STi/o links 0 to 5.
Checksum Generator
Checksum =
255
Fiber Loop Synchronization
A receiver is declared in synchronization after
detection of three consecutive frames containing a
valid sync pattern. Once synchronized a receiver will
lose sync if a valid sync pattern is not detected in two
of four consecutive frames (refer to Figure 5).
∑
DATA i
+
C i
–1
i
=1
LED Control
The open collector RLED output (pin 36) will cause
an LED, pulled up to +5 volts, to flash at
Where i-1 is the carry out from the previous
operation. The checksum is calculated on all 255
channels except on channel 0 where the frame
synchronization code is transported. During this
channel the previous checksum is stored and the
register initialized for the next calculation.
5-11
MITEL [ MITEL NETWORKS CORPORATION ]
