0-1516-310-1516-310-1516-310-1516-310-15
Block
Channels
FS(R/X)
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
0 1 0 1 0 1 0 1 0
Partition A B A B A B A B A
Two-partition mode. Example with fixed block assignments
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Multichannel Selection Modes
687
SPRUI07–March 2020
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Multichannel Buffered Serial Port (McBSP)
12.6.4.1 Assigning Blocks to Partitions A and B
For reception, any two of the eight receive-channel blocks can be assigned to receive partitions A and B,
which means up to 32 receive channels can be enabled at any given point in time. Similarly, any two of
the eight transmit-channel blocks (up 32 enabled transmit channels) can be assigned to transmit partitions
A and B.
For reception:
• Assign an even-numbered channel block (0, 2, 4, or 6) to receive partition A by writing to the RPABLK
bits. In the receive multichannel selection mode (described in Section 12.6.6), the channels in this
partition are controlled by receive channel enable register A (RCERA).
• Assign an odd-numbered block (1, 3, 5, or 7) to receive partition B with the RPBBLK bits. In the
receive multichannel selection mode, the channels in this partition are controlled by receive channel
enable register B (RCERB).
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 12.6.7), 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 12-32 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.
Figure 12-32. Alternating Between the Channels of Partition A and the Channels of Partition B
As explained in Section 12.6.4.2, you can dynamically change which blocks of channels are assigned to
the partitions.
12.6.4.2 Reassigning Blocks During Reception/Transmission
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 cannot modify (R/X)PABLK to assign different channels to partition
A, nor (R/X)CERA to change the channel configuration for partition A.
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