5Serial Ports
5 – 31
a single word or continuous stream, with independent receive and
transmit operation. In the multichannel mode, the receive frame sync
signal (RFS0) identifies the start of a 24- or 32-word block of serial data
with the receiver and transmitter operating in parallel. TFS0 has an
alternate function, described below. Note: The ADSP-2105 has only one
serial port (SPORT1) and does not support multichannel operation.
5.12.1 Multichannel Setup
Multichannel operation is enabled by bit 15 in SPORT0’s control register
(0x3FF6). When this bit is a 1, multichannel mode is enabled, and some
control bits in the SPORT0 control register are redefined. Bits affected by
multichannel mode are shown in Figure 5.25. At reset, bit 15 is cleared,
disabling multichannel mode and enabling normal operation.
Figure 5.25 SPORT0 Control Register With Multichannel Mode Enabled
The state of the multichannel length bit MCL, bit 9, determines whether
there are 24 or 32 channels, i.e. whether the block length is 24 or 32 words.
A 0 selects 24-word blocks; a 1, 32-word blocks. In multichannel mode, the
SCLK
First Bit
RFS MFD=9
RFS MFD=8
RFS MFD=7
RFS MFD=6
RFS MFD=5
RFS MFD=1
RFS MFD=0
9 8 7 6 5 4 3 2 1
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