
MT90503
Data Sheet
60
Zarlink Semiconductor Inc.
4.3.2.3 Transmit Event Scheduler Fields Description
Table 18 - Field Description for the Transmit Event Scheduler provides a description of the fields for the transmit
event scheduler. Please refer to Figure 24 - Transmit Event Scheduler Process to locate the fields.
Table 18 - Field Description for the Transmit Event Scheduler
Field
Name of Field
Bits Used
Description of Field
I
Scheduler
Initialised Bit
+0/b15
This bit is reset by software immediately before enabling the
transmit event scheduler. Hardware will set this bit the first
time it reads the scheduler information structure. When the I
bit is read at ’0’ by hardware and the scheduler is used for
T1/E1 support, the transmit event scheduler's Current
Frame will be written between 0-23 for T1 and 0-15 for E1 in
order for frame 0 to correspond to the first byte of a
multiframe.
Turn Num
Free run
counter of
scheduler
wraps
+0/b13:b11
Turn Num is a counter used for the implementation of
multiframing. The scheduler re-synchronises itself with the
multiframe count when Turn Num is 0.
Current Frame
Current Frame
+0/b10:b0
Current Frame is used to record the frame position of the
transmit event scheduler.
Range 0 to (Last Frame)
Num Env
Number of
events per
frame in the
scheduler
+2/b7:b5
The number of events per frame is 2
(Num Env)+1
. The same
number applies to all frames in the scheduler. Range:000 to
101 (2 to 63 events per frame). All others reserved.
Read 2m
Events
Read 2m First
Events
+2/b4:b0
Indicates to the scheduler how many events in each frame
must be read. The same number applies to all frames in the
scheduler.
Scheduler Base
Address
Pointer to the
beginning of
the transmit
event
scheduler
+4/b14:b0
This field is appended with "00000" as the LSBs, to form a
20-bit address.
Note: A frame must never cross a boundary of its own size
in memory. Therefore, if the transmit event scheduler has
more than 8 events per frame (32 bytes per frame), then
some LSBs of this field must be 0.
Last Frame (M)
Last Frame
(M)
+6/b10:b0
Last Frame = (number of frames in the scheduler) - 1. If Last
Frame = 0, the scheduler is one frame long, if Last Frame =
1, the scheduler is two frames long, etc.
m
0
1
2
.
.
31
Events Read
64
2
4
.
.
62