15.8.9 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
15.8.9.1 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
Multichannel Buffered Serial Port (McBSP)
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
TMS320x2806x Microcontrollers
943
Copyright © 2022 Texas Instruments Incorporated
Summary of Contents for TMS320 2806 Series
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