Receiver Configuration
1120
SPRUHE8E – October 2012 – Revised November 2019
Copyright © 2012–2019, Texas Instruments Incorporated
C28 Multichannel Buffered Serial Port (McBSP)
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
15.8.9.1 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
15.8.10 Enable/Disable the Receive Frame-Synchronization Ignore Function
The RFIG bit (see
) 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.
15.8.10.1 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.