Transmitter Configuration
1140
SPRUHE8E – October 2012 – Revised November 2019
Copyright © 2012–2019, Texas Instruments Incorporated
C28 Multichannel Buffered Serial Port (McBSP)
15.9.9 Set the Transmit Frame Length
Table 15-55. Register Bits Used to Set the Transmit Frame Length
Register
Bit
Name
Function
Type
Reset Value
XCR1
14-8
XFRLEN1
Transmit frame length 1
R/W
000 0000
(X 1) is the number of serial words in phase 1 of the
transmit frame.
XFRLEN1 = 000 0000
1 word in phase 1
XFRLEN1 = 000 0001
2 words in phase 1
|
|
|
|
XFRLEN1 = 111 1111
128 words in phase 1
XCR2
14-8
XFRLEN2
Transmit frame length 2
R/W
000 0000
If a dual-phase frame is selected, (X 1) is the
number of serial words in phase 2 of the transmit frame.
XFRLEN2 = 000 0000
1 word in phase 2
XFRLEN2 = 000 0001
2 words in phase 2
|
|
|
|
XFRLEN2 = 111 1111
128 words in phase 2
15.9.9.1 Selected Frame Length
The transmit frame length is the number of serial words in the transmit frame. Each frame can have one or
two phases, depending on the value that you load into the XPHASE bit.
If a single-phase frame is selected (XPHASE = 0), the frame length is equal to the length of phase 1. If a
dual-phase frame is selected (XPHASE = 1), the frame length is the length of phase 1 plus the length of
phase 2.
The 7-bit XFRLEN fields allow up to 128 words per phase. See
for a summary of how to
calculate the frame length. This length corresponds to the number of words or logical time slots or
channels per frame-synchronization pulse.
NOTE:
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.
Table 15-56. How to Calculate Frame Length
XPHASE
XFRLEN1
XFRLEN2
Frame Length
0
0
≤
XFRLEN1
≤
127
Don't care
(X 1) words
1
0
≤
XFRLEN1
≤
127
0
≤
XFRLEN2
≤
127
(X 1) + (X 1) words