Multichannel Selection Modes
www.ti.com
686
SPRUI07–March 2020
Submit Documentation Feedback
Copyright © 2020, Texas Instruments Incorporated
Multichannel Buffered Serial Port (McBSP)
The blocks are assigned to partitions according to the selected partition mode. In the two-partition
mode (described in Section 12.6.4), you assign one even-numbered block (0, 2, 4, or 6) to partition A
and one odd-numbered block (1, 3, 5, or 7) to partition B. In the 8-partition mode (described in
Section 12.6.5), blocks 0 through 7 are automatically assigned to partitions, A through H, respectively.
Table 12-9. 2-Partition Mode
Partition Blocks
A 0 or 2 or 4 or 6
B 1 or 3 or 5 or 7
Table 12-10. 8-Partition mode
Partition Blocks Channels
A 0 0 -15
B 1 16 - 31
C 2 32 - 47
D 3 48 - 63
E 4 64 - 79
F 5 80 - 95
G 6 96 - 111
H 7 112 - 127
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).
12.6.2 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 Section 12.6.6) and three transmit
multichannel selection modes (described in Section 12.6.7).
12.6.3 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.
12.6.4 Using Two Partitions
For multichannel selection operation in the receiver and/or the transmitter, you can use two partitions or
eight partitions (described in Section 12.6.5). If you choose the 2-partition mode (RMCME = 0 for
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.
To Next Page
Loading...
Need help?
General
