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Multichannel Selection Modes
Figure 35.
Reassigning Channel Blocks Throughout a McBSP Data Transfer
Two-partition mode. Example with changing block assignments
Partition
A
Block
0
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
Block 2 assigned
to partition A
5.5
Using Eight Partitions
64
Multichannel Buffered Serial Ports (McBSPs)
The block of channels currently involved in reception/transmission (the
-
current block) is reflected in the RCBLK/XCBLK bits. Your program can
poll these bits to determine which partition is active. When a partition is not
active, it is safe to change its block assignment and channel configuration.
At the end of every block, at the boundary of two partitions, an interrupt can
-
be sent to the CPU. In response to the interrupt, the CPU can then check
the RCBLK/XCBLK bits and update the inactive partition. See section 5.8,
Using Interrupts Between Block Transfers.
Figure 35 shows an example of reassigning channels throughout a data
transfer. In response to a frame-synchronization pulse, the McBSP alternates
between partitions A and B. Whenever partition B is active, the CPU changes
the block assignment for partition A. Whenever partition A is active, the CPU
changes the block assignment for partition B.
B
A
B
1
2
3
16−31
32−47
48−63
Block 4 assigned
to partition A
Block 3 assigned
to partition B
For multichannel selection operation in the receiver and/or the transmitter, you
can use eight partitions or two partitions (described in section 5.4). If you
choose the 8-partition mode (RMCME = 1 for reception, XMCME = 1 for
transmission), McBSP channels are activated in the following order: A, B, C,
D, E, F, G, H. In response to a frame-synchronization pulse, the receiver or
transmitter begins with the channels in partition A and then continues with the
other partitions in order until the complete frame has been transferred. When
the next frame-synchronization pulse occurs, the next frame is transferred,
beginning with the channels in partition A.
A
B
4
5
64−79
80−95
96−111
Block 6 assigned
to partition A
Block 5 assigned
Block 7 assigned
to partition B
to partition B
A
B
A
6
7
0
112−127
0−15
Block 0 assigned
to partition A
Block 1 assigned
to partition B
SPRU762B
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