Programming Model
10-60
ADSP-214xx SHARC Processor Hardware Reference
In the ADSP-214xx processors the
FSED
bit in the
SPCTLN
register
allows SPORT initialization regardless of the state of the external
frame sync. The SPORT starts the transfer on the next valid edge.
Companding As a Function
Since the values in the transmit and receive buffers are actually com-
panded in place, the companding hardware can be used without
transmitting (or receiving) any data, for example during testing or debug-
ging. This operation requires one peripheral clock cycle of overhead, as
described below. For companding to execute properly, program the
SPORT registers prior to loading data values into the SPORT buffers.
To compress data in place without transmitting use the following
procedure.
1. Set the
SPTRAN
bit to 1 in the
SPCTLx
register. The
SPEN_A
and
SPEN_B
bits should be = 0.
2. Enable companding in the
DTYPE
field of the
SPCTLx
transmit con-
trol register.
3. Write a 32-bit data word to the transmit buffer. Companding is
calculated in this cycle.
4. Wait two cycles. Any instruction not accessing the transmit buffer
can be used to cause this delay. This allows the serial port com-
panding hardware to reload the transmit buffer with the
companded value.
5. Read the 8-bit compressed value from the transmit buffer.
To expand data in place, use the same sequence of operations with the
receive buffer instead of the transmit buffer. When expanding data in this
way, set the appropriate serial word length (
SLEN
) in the
SPCTLx
register.
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Содержание SHARC ADSP-214 Series
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Страница 72: ...Notation Conventions lxxii ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 130: ...Programming Model 2 52 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 264: ...Programming Models 3 134 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
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Страница 396: ...Effect Latency 7 28 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 520: ...Programming Model 10 62 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 616: ...Debug Features 14 22 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 656: ...Programming Model 15 40 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 714: ...Programming Model 19 10 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 1132: ...Register Listing A 306 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 1192: ...Index I 34 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...