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McBSP Registers
757
SPRUI07–March 2020
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Multichannel Buffered Serial Port (McBSP)
Figure 12-74. Transmit Control 2 Register (XCR2)
15 14 8
XPHASE XFRLEN2
R/W-0 R/W-0
7 5 4 3 2 1 0
XWDLEN2 XCOMPAND XFIG XDATDLY
R/W-0 R/W-0 R/W-0 R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 12-85. Transmit Control 2 Register (XCR2) Field Descriptions
Bit Field Value Description
15 XPHASE Transmit phase number bit. XPHASE determines whether the transmit frame has one phase or two
phases. For each phase you can define the serial word length and the number of serial words in the
phase. To set up phase 1, program XWDLEN1 (word length) and XFRLEN1 (number of words). To set
up phase 2 (if there are two phases), program XWDLEN2 and XFRLEN2.
0 Single-phase frame
The transmit frame has only one phase, phase 1.
1 Dual-phase frame
The transmit frame has two phases, phase 1 and phase 2.
14-8 XFRLEN2 0-7Fh Transmit frame length 2 (1 to 128 words). Each frame of transmit data can have one or two phases,
depending on value that you load into the XPHASE bit. If a single-phase frame is selected, XFRLEN1 in
XCR1 selects the number of serial words (8, 12, 16, 20, 24, or 32 bits per word) in the frame. If a dual-
phase frame is selected, XFRLEN1 determines the number of serial words in phase 1 of the frame and
XFRLEN2 in XCR2 determines the number of words in phase 2 of the frame. The 7-bit XFRLEN fields
allow up to 128 words per phase. See Table 12-86 for a summary of how to determine the frame length.
This length corresponds to the number of words or logical time slots or channels per frame-
synchronization period.
Program the XFRLEN fields with [w minus 1], where w represents the number of words per phase. For
example, if you want a phase length of 128 words in phase 1, load 127 into XFRLEN1.
7-5 XWDLEN2 0-7h Transmit word length 2. Each frame of transmit data can have one or two phases, depending on the
value that you load into the XPHASE bit. If a single-phase frame is selected, XWDLEN1 in XCR1
selects the length for every serial word transmitted in the frame. If a dual-phase frame is selected,
XWDLEN1 determines the length of the serial words in phase 1 of the frame and XWDLEN2 in XCR2
determines the word length in phase 2 of the frame.
0 8 bits
1h 12 bits
2h 16 bits
3h 20 bits
4h 24 bits
5h 32 bits
6h-7h Reserved (do not use)
4-3 XCOMPAN
D
0-3h Transmit companding mode bits. Companding (COMpress and exPAND) hardware allows compression
and expansion of data in either μ-law or A-law format. For more details, see Section 12.3.2.
XCOMPAND allows you to choose one of the following companding modes for the McBSP transmitter.
For more details about these companding modes, see Section 12.3.2.
0 No companding, any size data, MSB transmitted first
1h No companding, 8-bit data, LSB transmitted first
2h μ-law companding, 8-bit data, MSB transmitted first
3h A-law companding, 8-bit data, MSB transmitted first
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