Texas Instruments OMAP36 Series, Техническое справочное руководство

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Partition
FS(R/X)
0-15
0
A
Block
Channels 16-31
1
B
32-47
2
C
48-63
3
D
0-15
0
A
64-79
4
E
80-95
5
F
96-111
6
G
112-127
7
H
8-partition mode
mcbsp-042
Public Version
McBSP Functional Description
www.ti.com
Figure 21-47 shows an example of the McBSP using the 8-partition mode. In response to a
frame-synchronization pulse, the McBSP module begins a frame transfer with partition A and then
activates B, C, D, E, F, G, and H to complete a 128-word frame.
Figure 21-47. McBSP Data Transfer in 8-Partition Mode
21.4.6.5 Receive Multichannel Selection Mode
The McBSPi. MCBSPLP_MCR1_REG [0] RMCM bit determines whether all channels or only selected
channels are enabled for reception.
• When RMCM = 0, all 128 receive channels are enabled and cannot be disabled.
• When RMCM = 1, the receive multichannel selection mode is enabled. In this mode:
– Channels can be individually enabled or disabled. The enabled channels are those selected in the
appropriate receive channel enable registers (McBSPi.
MCBSPLP_RCERA_REG to
McBSPi. MCBSPLP_RCERH_REG ). The channels are assigned to the
McBSPi. MCBSPLP_RCERA_REG to McBSPi. MCBSPLP_RCERH_REG registers depends on the
number of receive channel partitions (2 or 8), as defined by the McBSPi. MCBSPLP_MCR1_REG [9]
RMCME bit.
– If a receive channel is disabled, any bits received in that channel are not transferred to the RB, and
as a result, the receiver ready bit (RRDY) is not set. Therefore, no DMA synchronization event is
generated and, if the receiver interrupt mode depends on RRDY
(McBSPi.
MCBSPLP_SPCR1_REG [5:4] RINTM = 0b00), no interrupt is generated.
As an example of how the McBSP module behaves in the receive multichannel selection mode, suppose
you enable only channels 0, 15, and 39 and that the frame length is 40. The McBSP module:
1. Accepts bits shifted in from the mcbspi_dr pin in channel 0
2. Ignores bits received in channels 1–14
3. Accepts bits shifted in from the mcbspi_dr pin in channel 15
4. Ignores bits received in channels 16–38
5. Accepts bits shifted in from the mcbspi_dr pin in channel 39
21.4.6.6 Using Two Partitions (Legacy Only)
For multichannel selection operation in the receiver and/or the transmitter, you can use two partitions or
eight partitions. If you choose the 2-partition mode (McBSPi.
MCBSPLP_MCR1_REG [9] RMCME = 0 for
reception, McBSPi. MCBSPLP_MCR2_REG [9] 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.
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. 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
McBSPi.
MCBSPLP_MCR1_REG [6:5] RPABLK field. In the receive multichannel selection mode, the
channels in this partition are controlled by receive channel enable register A
(McBSPi.
MCBSPLP_RCERA_REG ).
3116 Multi-Channel Buffered Serial Port SWPU177N – December 2009 – Revised November 2010
Copyright © 2009–2010, Texas Instruments Incorporated