Companding And Data Format - Analog Devices adsp-2100 Manual

Figures 5.16 to 5.21 show framing for transmitting data and are very
similar to Figures 5.10 to 5.15. In Figures 5.16 and 5.17, the normal framing
mode is shown for noncontinuous data and continuous data. Figures 5.18
and 5.19 show noncontinuous and continuous transmission in the
alternate framing mode. As with receive timing, the TFS output meets the
TFS input timing requirement.
Figures 5.20 and 5.21 show the transmit operation with normal framing
and alternate framing, respectively, in the unframed mode. There is a
single the frame sync signal that occurs only at the start of the first word,
either one SCLK before the first bit (normal) or at the same time as the first
bit (alternate).
5.10

COMPANDING AND DATA FORMAT

Companding (a contraction of COMpressing and exPANDing) is the
process of logarithmically encoding and decoding data to minimize the
number of bits that must be sent. Both SPORTs share the companding
hardware; one expansion and one compression operation can occur in
each processor cycle. In the event of contention, SPORT0 has priority.
SPORT0 Control Register: 0x3FF6
SPORT1 Control Register: 0x3FF2
15 14 13 12 11
Figure 5.22 DTYPE Field In SPORT Control Register
Serial Ports
10 9 8 7
DTYPE 00=Right justify, zero fill unused MSBs
01=Right justify, sign extend into unused MSBs
10=Compand using µ-law
11=Compand using A-law
6 5 4 3 2
5
1 0
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