McBSP Registers
1130
SPRUH22I – April 2012 – Revised November 2019
Copyright © 2012–2019, Texas Instruments Incorporated
C28 Multichannel Buffered Serial Port (McBSP)
15.12.6.2 Transmit Control 2 Register (XCR2)
The transmit control 2 register (XCR2) is shown in
and described in
.
Figure 15-72. 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 15-80. 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
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
.
XCOMPAND allows you to choose one of the following companding modes for the McBSP transmitter.
For more details about these companding modes, see
.
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