CN8478/CN8474A/CN8472A/CN8471A
5.0 Memory Organization
Multichannel Synchronous Communications Controller (MUSYCC™)
5.2 Descriptors
Numerous mappings of time slots to channels are possible. Multiple time slots
can be mapped to a single channel; however, each time slot can map to only one
channel at a time. When the number of active time slots exceeds the number of
channels in a group (greater than 32 time slots), and each time slot requires a
separate channel, MUSYCC can be configured to internally connect 2 or 4
channel groups together to provide up to 64- or 128-channel support, respectively.
Two time slot maps are required for each channel group, one for transmit
functions and one for receive functions. The two maps are configured
independently. Each map consists of 128 successive 8-bit fields, each
corresponding to one time slot. The bit field includes the following information:
•
•
Time Slot Enabled/Time Slot (TSEN) Mode of Operation (64 kbps,
56 kbps, subchannel) indicator
Logical channel number (0–31) associated with time slot (CH)
For disabled time slots, modes and logical channels can be assigned, but the
information does not apply to the operation of the channel.
For enabled time slots, the valid modes of operation include the following:
•
•
64 kbps Mode: all 8 bits of time slot are assigned to one channel.
56 kbps Mode: first 7 bits of time slot are assigned to one channel. Last bit,
Most Significant Bit (MSB), is unassigned and considered disabled.
Subchannel Mode, Bit 0 Disabled: first bit, Least Significant Bit (LSB), of
time slot is unassigned. Each of the next 7 bits in time slot can be
individually enabled and independently mapped to any channel in a
channel group.
•
•
Subchannel Mode, Bit 0 Enabled: first bit (LSB) of time slot is always
enabled and assigned to a channel in a channel group. Each of the next
7 bits in time slot can be individually enabled and independently mapped
to any channel in a channel group.
The logical channel number represents the channel in the channel group
handling the bit stream from the time slot or slots assigned to it. The value of the
channel number ranges from 0–31.
100660E
Conexant
5-21
CONEXANT [ CONEXANT SYSTEMS, INC ]
