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Multichannel Selection Modes
The blocks are assigned to partitions according to the selected partition mode. In the two-partition
mode (described in
and one odd-numbered block (1, 3, 5, or 7) to partition B. In the 8-partition mode (described in
Section
15.6.5), blocks 0 through 7 are automatically assigned to partitions, A through H, respectively.
The number of partitions for reception and the number of partitions for transmission are independent. For
example, it is possible to use two receive partitions (A and B) and eight transmit partitions (A-H).
15.6.2 Multichannel Selection
When a McBSP uses a time-division multiplexed (TDM) data stream while communicating with other
McBSPs or serial devices, the McBSP may need to receive and/or transmit on only a few channels. To
save memory and bus bandwidth, you can use a multichannel selection mode to prevent data flow in
some of the channels.
Each channel partition has a dedicated channel enable register. If the appropriate multichannel selection
mode is on, each bit in the register controls whether data flow is allowed or prevented in one of the
channels that is assigned to that partition.
The McBSP has one receive multichannel selection mode (described in
multichannel selection modes (described in
15.6.3 Configuring a Frame for Multichannel Selection
Before you enable a multichannel selection mode, make sure you properly configure the data frame:
•
Select a single-phase frame (RPHASE/XPHASE = 0). Each frame represents a TDM data stream.
•
Set a frame length (in RFRLEN1/XFRLEN1) that includes the highest-numbered channel to be used.
For example, if you plan to use channels 0, 15, and 39 for reception, the receive frame length must be
at least 40 (RFRLEN1 = 39). If XFRLEN1 = 39 in this case, the receiver creates 40 time slots per
frame but only receives data during time slots 0, 15, and 39 of each frame.
15.6.4 Using Two Partitions
For multichannel selection operation in the receiver and/or the transmitter, you can use two partitions or
eight partitions (described in
reception, XMCME = 0 for transmission), McBSP channels are activated using an alternating scheme. In
response to a frame-synchronization pulse, the receiver or transmitter begins with the channels in partition
A and then alternates between partitions B and A 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.
1102
C28 Multichannel Buffered Serial Port (McBSP)
Section
15.6.4), you assign one even-numbered block (0, 2, 4, or 6) to partition A
Table 15-9. 2-Partition Mode
Partition
A
B
Table 15-10. 8-Partition mode
Partition
Blocks
A
B
C
D
E
F
G
H
Section
Section
15.6.5). If you choose the 2-partition mode (RMCME = 0 for
Copyright © 2012–2019, Texas Instruments Incorporated
Blocks
0 or 2 or 4 or 6
1 or 3 or 5 or 7
Channels
0
0 -15
1
16 - 31
2
32 - 47
3
48 - 63
4
64 - 79
5
80 - 95
6
96 - 111
7
112 - 127
Section
15.6.7).
SPRUHE8E – October 2012 – Revised November 2019
www.ti.com
15.6.6) and three transmit
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