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Figure 34.
Alternating Between the Channels of Partition A and the Channels of
Partition B
Two-partition mode. Example with fixed block assignments
Partition
Block
Channels
0−15
Á Á Á Á Á Á Á Á Á Á Á Á Á Á Á Á Á Á Á Á Á Á Á Á Á
FS(R/X)
Á Á Á Á Á Á Á Á Á Á Á Á Á Á Á Á Á Á Á Á Á Á Á Á Á
5.4.2
Reassigning Blocks During Reception/Transmission
SPRU762B
For transmission:
Assign an even-numbered channel block (0, 2, 4, or 6) to transmit partition
-
A by writing to the XPABLK bits. In one of the transmit multichannel
selection modes (described in section 5.7), the channels in this partition
are controlled by transmit channel enable register A (XCERA).
Assign an odd-numbered block (1, 3, 5, or 7) to transmit partition B with
-
the XPBBLK bits. In one of the transmit multichannel selection modes, the
channels in this partition are controlled by transmit channel enable register
B (XCERB).
Figure 34 shows an example of alternating between the channels of partition
A and the channels of partition B. Channels 0 -15 have been assigned to
partition A, and channels 16-31 have been assigned to partition B. In response
to a frame-synchronization pulse, the McBSP begins a frame transfer with
partition A and then alternates between partitions B and A until the complete
frame is transferred.
A
B
A
0
1
0
16−31
0−15
As explained in section 5.4.2, you can dynamically change which blocks of
channels are assigned to the partitions.
If you want to use more than 32 channels, you can change which channel
blocks are assigned to partitions A and B during the course of a data transfer.
However, these changes must be carefully timed. While a partition is being
transferred, its associated block assignment bits cannot be modified and its
associated channel enable register cannot be modified. For example, if block
3 is being transferred and block 3 is assigned to partition A, you can modify
neither (R/X)PABLK to assign different channels to partition A nor (R/X)CERA
to change the channel configuration for partition A. Several features of the
McBSP help you time the reassignment:
Multichannel Selection Modes
B
A
B
1
0
1
16−31
0−15
16−31
Multichannel Buffered Serial Ports (McBSPs)
A
B
A
0
1
0
0−15
16−31
0−15
63
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