DXR-to-XSR copy
DXR-to-XSR copy
DXR-to-XSR copy
DXR-to-XSR copy
DX
FSX
CLKX
Element 4
Element 3
Element 2
DR
Element 1
FSR
CLKR
RBR-to-DRR copy
RBR-to-DRR copy
RBR-to-DRR copy
RBR-to-DRR copy
(R/X)SYNCERR
(low)
A0
D(R/X)
FS(R/X)
C4
C5
C6
B0
B1
B2
B3
B4
B5
B6
B7
C7
CLK(R/X)
Frame synchronization ignored
Architecture
1214
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Multichannel Buffered Serial Port (McBSP)
shows McBSP operation when unexpected internal or external frame synchronization signals
are ignored by setting (R/X)FIG = 1. Here, the transfer of element B is not affected by an unexpected
frame synchronization.
Figure 25-20. Unexpected Frame Synchronization With (R/X)FIG = 1
25.2.7.4.2 Data Packing using Frame Sync Ignore Bits
describes one method of changing the element length and frame length to simulate 32-
bit serial element transfers, thus requiring much less bus bandwidth than four 8-bit transfers require. This
example works when there are multiple elements per frame.
Now consider the case of the McBSP operating at maximum packet frequency, as shown in
.
Here, each frame has only a single 8-bit element. This stream takes one read transfer and one write
transfer for each 8-bit element.
shows the McBSP configured to treat this stream as a
continuous stream of 32-bit elements. In this example, (R/X)FIG is set to 1 to ignore unexpected
subsequent frames. Only one read transfer and one write transfer is needed every 32 bits. This
configuration effectively reduces the required bus bandwidth to one-fourth of the bandwidth needed to
transfer four 8-bit blocks.
Figure 25-21. Maximum Frame Frequency Operation With 8-Bit Data