Registers
1257
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Multichannel Buffered Serial Port (McBSP)
25.3.9 Enhanced Transmit Channel Enable Registers (XCERE0-XCERE3)
The enhanced transmit channel enable register (XCERE
n
) is shown in
and described in
. The XCERE
n
is used to enable any of 128 elements for transmit. XCERE0 is the only
register used in normal mode (up to 32 channels can be selected in partitions A and B, RMCME =
XMCME = 0 in MCR). XCERE0-XCERE3 are used when in enhanced mode (up to 128 channels can be
selected in all partitions, RMCME = XMCME = 1 in MCR).
The transmit multichannel partition mode (XMCME) bit in the multichannel control register (MCR) is only
applicable if channels can be individually disabled/enabled or masked/unmasked for transmission (XMCM
is nonzero). The XMCME bit determines whether only 32 channels or all 128 channels are to be
individually selectable:
•
When XMCME = 0:
Only partitions A and B are used. XCERE0 is used to enable any of the 32
elements for a transmit. Of the 32 elements, 16 channels belong to a subframe in partition A and 16
channels belong to a subframe in partition B. The XCE0-XCE15 bits enable elements within the 16-
channel elements in partition A and the XCE16-XCE31 bits enable elements within the 16-channel
elements in partition B. You can control up to 32 channels in the transmit multichannel selection mode
selected with the XMCM bit in MCR.
•
When XMCME = 1:
All partitions are used. XCERE0 is used to enable any of the 32 elements in
channels 0 through 31 for a transmit. Of the 32 elements, channels 0 to 15 belong to a subframe in
partition A and channels 16 to 31 belong to a subframe in partition B. The XCE0-XCE15 bits enable
elements within the 16-channel elements in partition A and the XCE16-XCE31 bits enable elements
within the 16-channel elements in partition B.
shows the 128 channels in a multichannel data stream and their corresponding enable
bits in XCERE
n
.
Figure 25-50. Enhanced Transmit Channel Enable Register n (XCEREn)
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
XCE31
XCE30
XCE29
XCE28
XCE27
XCE26
XCE25
XCE24
XCE23
XCE22
XCE21
XCE20
XCE19
XCE18
XCE17
XCE16
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
XCE15
XCE14
XCE13
XCE12
XCE11
XCE10
XCE9
XCE8
XCE7
XCE6
XCE5
XCE4
XCE3
XCE2
XCE1
XCE0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
LEGEND: R/W = Read/Write; -n = value afer reset
Table 25-32. Enhanced Transmit Channel Enable Register n (XCEREn) Field Descriptions
Bit
Field
Value
Description
31-0
XCE
n
Transmit channel enable bit. The role of this bit depends on which transmit multichannel mode is selected
with the XMCM bit in MCR:
When XMCM = 1h (all channels disabled unless selected):
0
Disable and mask the channel that is mapped to XCE
n.
1
Enable and unmask the channel that is mapped to XCE
n
.
When XMCM = 2h (all channels enabled but masked unless selected)
:
0
Mask the channel that is mapped to XCE
n
.
1
Unmask the channel that is mapped to XCE
n
.
When XMCM = 3h (all channels masked unless selected):
0
Mask the channel that is mapped to XCE
n
. Even if this channel is enabled by the corresponding
enhanced receive channel enable bit, this channel's data cannot appear on the DX pin.
1
Unmask the channel that is mapped to XCE
n
. Even if this channel is also enabled by the corresponding
enhanced receive channel enable bit, full transmission can occur.