McBSP Registers
1129
SPRUH22I – April 2012 – Revised November 2019
Copyright © 2012–2019, Texas Instruments Incorporated
C28 Multichannel Buffered Serial Port (McBSP)
•
Specify one or two phases for each frame of transmit data (XPHASE)
•
Define two parameters for phase 1 and (if necessary) phase 2: the serial word length (XWDLEN1,
XWDLEN2) and the number of words (XFRLEN1, XFRLEN2)
•
Choose a transmit companding mode, if any (XCOMPAND)
•
Enable or disable the transmit frame-sync ignore function (XFIG)
•
Choose a transmit data delay (XDATDLY)
15.12.6.1 Transmit Control 1 Register (XCR1)
The transmit control 1 register (XCR1) is shown in
and described in
.
Figure 15-71. Transmit Control 1 Register (XCR1)
15
14
8
Reserved
XFRLEN1
R-0
R/W-0
7
5
4
0
XWDLEN1
Reserved
R/W-0
R-0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 15-78. Transmit Control 1 Register (XCR1) Field Descriptions
Bit
Field
Value
Description
15
Reserved
0
Reserved bit. Read-only; returns 0 when read.
14-8
XFRLEN1
0-7Fh
Transmit frame length 1 (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 you
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
XWDLEN1
0-3h
Transmit word length 1. 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)
4-0
Reserved
0
Reserved bits. They are read-only bits and return 0s when read.
Table 15-79. Frame Length Formula for Transmit Control 1 Register (XCR1)
XPHASE
XFRLEN1
XFRLEN2
Frame Length
0
0
≤
XFRLEN1
≤
127
Not used
(X 1) words
1
0
≤
XFRLEN1
≤
127
0
≤
XFRLEN2
≤
127
(X 1) + (X 1) words