Table 15-27. Register Bits Used to Set the Receive Frame Length (continued)
Register
Bit
Name
Function
Type
Reset
Value
RCR2
14-8
RFRLEN2
Receive frame length 2
R/W
000 0000
If a dual-phase frame is selected, (R 1) is the number of serial words in
phase 2 of the receive frame.
RFRLEN2 = 000 0000
1 word in phase 2
RFRLEN2 = 000 0001
2 words in phase 2
|
|
|
|
RFRLEN2 = 111 1111
128 words in phase 2
15.7.9.1 Selected Frame Length
The receive frame length is the number of serial words in the receive frame. Each frame can have one or two
phases, depending on value that you load into the RPHASE bit.
If a single-phase frame is selected (RPHASE = 0), the frame length is equal to the length of phase 1. If a
dual-phase frame is selected (RPHASE = 1), the frame length is the length of phase 1 plus the length of phase
2.
The 7-bit RFRLEN 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.
Program the RFRLEN fields with [
w minus 1
], where
w
represents the number of words per phase. For the
example, if you want a phase length of 128 words in phase 1, load 127 into RFRLEN1.
Table 15-28. How to Calculate the Length of the Receive Frame
RPHASE
RFRLEN1
RFRLEN2
Frame Length
0
0 ≤ RFRLEN1 ≤ 127
Don't care
(R 1) words
1
0 ≤ RFRLEN1 ≤ 127
0 ≤ RFRLEN2 ≤ 127
(R 1) + (R 1) words
15.7.10 Enable/Disable the Receive Frame-Synchronization Ignore Function
) controls the receive frame-synchronization ignore function.
Table 15-29. Register Bit Used to Enable/Disable the Receive Frame-Synchronization Ignore Function
Register
Bit
Name
Function
Type
Reset
Value
RCR2
2
RFIG
Receive frame-synchronization ignore
R/W
0
RFIG = 0
An unexpected receive frame-synchronization pulse causes the McBSP to
restart the frame transfer.
RFIG = 1
The McBSP ignores unexpected receive frame-synchronization pulses.
15.7.10.1 Unexpected Frame-Synchronization Pulses and the Frame-Synchronization Ignore Function
If a frame-synchronization pulse starts the transfer of a new frame before the current frame is fully received, this
pulse is treated as an unexpected frame-synchronization pulse.
When RFIG = 1, reception continues, ignoring the unexpected frame-synchronization pulses.
When RFIG = 0, an unexpected FSR pulse causes the McBSP to discard the contents of RSR[1,2] in favor of
the new incoming data. Therefore, if RFIG = 0 and an unexpected frame-synchronization pulse occurs, the serial
port:
1. Aborts the current data transfer
2. Sets RSYNCERR in SPCR1 to 1
3. Begins the transfer of a new data word
Multichannel Buffered Serial Port (McBSP)
924
TMS320x2806x Microcontrollers
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
Copyright © 2022 Texas Instruments Incorporated
Содержание TMS320 2806 Series
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