(R/X)SYNCERR
D(R/X)
FS(R/X)
CLK(R/X)
C4
C5
C6
C7
B0
B1
B2
B3
B4
B5
B6
B7
A0
ÁÁ
ÁÁ
ÁÁ
ÁÁ
Frame synchronization ignored
Current data retransmitted
New data received
(R/X)SYNCERR
DX
DR
FS(R/X)
CLK(R/X)
C6
C7
B0
ÁÁ
ÁÁ
ÁÁ
B2
B3
B4
B5
B7
B6
B6
B7
A0
B1
D6
D7
C0
C1
C2
C3
C4
C5
C6
C7
B6
B7
A0
ÁÁ
ÁÁ
ÁÁ
ÁÁ
Frame synchronization aborts current transfer
Receiver Configuration
1084
SPRUH22I – April 2012 – Revised November 2019
Copyright © 2012–2019, Texas Instruments Incorporated
C28 Multichannel Buffered Serial Port (McBSP)
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
For more details about the frame-synchronization error condition, see
Unexpected Receive
Frame-Synchronization Pulse
.
15.8.10.2 Examples of Effects of RFIG
shows an example in which word B is interrupted by an unexpected frame-synchronization
pulse when (R/X)FIG = 0. In the case of reception, the reception of B is aborted (B is lost), and a new data
word (C in this example) is received after the appropriate data delay. This condition is a receive
synchronization error, which sets the RSYNCERR bit.
Figure 15-43. Unexpected Frame-Synchronization Pulse With (R/X)FIG = 0
In contrast with
,
shows McBSP operation when unexpected frame-
synchronization signals are ignored (when (R/X)FIG = 1). Here, the transfer of word B is not affected by
an unexpected pulse.
Figure 15-44. Unexpected Frame-Synchronization Pulse With (R/X)FIG = 1
15.8.11 Set the Receive Companding Mode
The RCOMPAND bits (see
) determine whether companding or another data transfer option is
chosen for McBSP reception.
Table 15-30. Register Bits Used to Set the Receive Companding Mode
Register
Bit
Name
Function
Type
Reset
Value
RCR2
4-3
RCOMPAND Receive companding mode
R/W
00
Modes other than 00b are enabled only when the appropriate RWDLEN is
000b, indicating 8-bit data.
RCOMPAND = 00 No companding, any size data, MSB received first
RCOMPAND = 01 No companding, 8-bit data, LSB received first (for details,
see
).
RCOMPAND = 10
μ
-law companding, 8-bit data, MSB received first
RCOMPAND = 11 A-law companding, 8-bit data, MSB received first