pef20550 Infineon Technologies Corporation, pef20550 Datasheet - Page 265

• Manufacturer Part Number: pef20550
• Description: Extended Line Card Interface Controller Elic
• Manufacturer: Infineon Technologies Corporation

PEB 20550
PEF 20550
Application Hints
5.4.2
Subchannel Switching
The switching of subchannels is programmed by first specifying the timeslot (which is
always 8 bits wide) to be switched, then by restricting the actual switching operation to
the desired bandwidth and sub-timeslot position. The switching function for an (8 bit) CFI
timeslot is programmed in the control memory (CM) by writing a pointer that points to an
(8 bit) PCM timeslot to the corresponding data field location. The MADR register
contains the pointer (PCM timeslot) and the MAAR register is used to specify the CFI
timeslot.
The ‘8 bit’ connection can now be restricted to the desired 4 or 2 bit connection by
selecting an appropriate control memory code. The code is programmed via
MACR:CMC3 … 0. These subchannel codes perform two functions: they specify the
bandwidth (actual number of bits to be switched) and the location of the sub-timeslot
within the selected (8 bit) PCM timeslot. The location of the sub-timeslot within the
selected (8 bit) CFI timeslot is predefined by the setting of the CSCR register. Each CFI
port can be set to a different sub-timeslot mode. In each mode a certain relationship
exists between programmed bandwidth (which can still be individually selected for each
CFI timeslot) and the occupied bit positions within the timeslot (which is fixed for each
CFI port by the CSCR register).
It should be noted that only one sub-timeslot can exist within a given CFI timeslot. On
the PCM side however each timeslot may be split up into 2
4 bits, 4
2 bits or any
mixture of these.
The CSCR register has the following format:
CFI Subchannel Register
read/write
reset value:
00
H
bit 7
bit 0
CSCR
SC31
SC30
SC21
SC20
SC11
SC10
SC01
SC00
Below, all possible combinations of subchannel switching between the CFI and PCM
interfaces are shown:
Semiconductor Group
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