Data Transmission and Reception
11-26
Figure 11–8.Dual-Phase Frame Example
D(R/X)
FS(R/X)
CLK(R/X)
Element 3
Phase 2
Element 2
Phase 2
Element 1
Phase 2
Element 2
Phase 1
Element 1
Phase 1
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Table 11–9.
RCR/XCR Fields Controlling Elements per Frame and Bits per Element
Serial Port
RCR/XCR field Control
Serial Port
McBSP0/1
Frame Phase
Elements per Frame
Bits per Element
Receive
1
RFRLEN1
RWDLEN1
Receive
2
RFRLEN2
RWDLEN2
Transmit
1
XFRLEN1
XWDLEN1
Transmit
2
XFRLEN2
XWDLEN2
11.3.4.3 Phase 2 Control: (R/X) PHASE2
This feature is available only in the ’C6211/C6711 device. The (R/X)PHASE2
bits in the (R/X)CR register determine when the second phase starts in a dual
phase frame. This feature is to support more varieties of IIS formats. Note that
the McBSP in the other ’C6000 family of devices does support some IIS for-
mats.
The start of second phase can be controlled by setting the (R/X)PHASE2 bit.
When (R/X)PHASE 2 is zero, the start of phase 2 is unaffected by the receive/
transmit frame sync. As shown in Figure 11–8, phase 2 starts as soon as
phase 1 is finished. When (R/X)PHASE2 = 1, the first phase starts as soon as
the frame sync goes active (low if FS(R/X)P = 1, high if FS(R/X)P = 0). The
second phase starts when the frame sync transitions to the opposite edge that
started the first phase as shown in Figure 11–9. If FS(R/X) is an output driven
by the McBSP, FWID determines the duration of Phase 1, and FPER
determines the total frame period for the two phases. If FS(R/X) is an input,
the frame sync transition after the first phase is detected and the second phase
transmission/reception is initiated.
For all dual phase frames, phase 1 and phase 2 can have elements with differ-
ent word lengths. Hence, WDLEN1 can be different than WDLEN2. Setting the
(R/X)PHASE2 bit also allows dead time between Phase 1 and Phase 2 as
shown in Figure 11–9. All data delays are still valid with this set up.