Changing Element Selection; End-Of-Subframe Interrupt; Enhanced Multichannel Selection Mode (C64X Dsp Only) - Texas Instruments TMS320C6000 Reference Manual

8.2.1

Changing Element Selection

8.2.2

End-of-Subframe Interrupt

8.3

Enhanced Multichannel Selection Mode (C64x DSP only)

SPRU580C
Using the multichannel selection feature, a static group of 32 elements can be
enabled and remains enabled with no CPU intervention until this allocation is
modified. An arbitrary number of, group of, or all of the elements within a frame
can be accessed by updating the block allocation registers during the course
of the frame in response to the end-of-subframe interrupts (see section 8.2.2
for information about these interrupts).
Note:
You must be careful not to affect the currently selected subframe when chang-
ing the selection.
The currently selected subframe is readable through the RCBLK and XCBLK
bits in MCR for receive and transmit, respectively. The associated channel
enable register cannot be modified if it is selected by the appropriate
(R/X)P[A/B]BLK register to point toward the current subframe. Similarly, the
(R/X)PABLK and (R/X)PBBLK bits in MCR cannot be modified while pointing to
or being changed to point to the currently selected subframe. If the total number
of elements is 16 or less, the current partition is always pointed to. In this case,
only a reset of the serial port can change the element enabling.
At the end of every subframe (16 elements or less) boundary during multichannel
operation, the receive interrupt (RINT), if RINTM = 01b in SPCR, or transmit
interrupt (XINT), if XINTM = 01b in SPCR, is generated to the CPU. This
interrupt indicates that a new partition has been crossed. You can then check
the current partition and change the selection of subframes in the A and/or B
partitions if they do not point to the current subframe. These interrupts are two
CPU-clock high pulses. If RINTM = XINTM = 01b when (R/X)MCM = 0
(non-multichannel operation), interrupts are not generated.
In addition to the normal multichannel selection mode, the C64x McBSP has
the enhanced multichannel selection mode that allows up to 128 channels to
be enabled at any given time. The enhanced multichannel selection mode is
selected by setting the enhanced receive multichannel selection enable bit
(RMCME) and the enhanced transmit multichannel selection enable bit
(XMCME) in MCR to 1. This mode works in conjunction with six additional
enhanced receive/transmit channel enable registers in the C64x McBSP:
RCERE1, RCERE2, RCERE3, XCERE1, XCERE2, and XCERE3. The RCER
and XCER described in section 11.8 are replaced by the RCERE0 and
XCERE1, respectively, in the C64x McBSP.
Multichannel Selection Operation
Multichannel Buffered Serial Port (McBSP) 73