ADSP-214xx SHARC Processor Hardware Reference
8-9
Media Local Bus
the local channel buffer memory is 124 quadlets. At reset each channel has
four quadlets each.
The buffer depth, buffer threshold and buffer start address for each chan-
nel is programmed using the respective
MLB_LCBCRx
register. The buffer
threshold is used by hardware channels in I/O mode only.
Hardware uses the local channel buffer threshold to determine when to
issue an I/O service request to system software. I/O service requests are
generated when:
• The number of valid qualdets in the local channel buffer falls
below the threshold for transmit channels or:
valid quadlets <=
MLB_LCBCRx
(programmed using
TH
bits)
Figure 8-2. Local Channel Buffer Threshold Mechanism
TX DATA
INPUT
TX DATA
OUTPUT
TRANSMIT SERVICE REQUEST GENERATED
(NUMBER OF VALID DATA QUADLETS <= BUFFER THRESHOLD)
RX DATA
OUTPUT
RX DATA
INPUT
RECEIVE SERVICE REQUEST GENERATED
(NUMBER OF FREE DATA QUADLETS <= BUFFER THRESHOLD)
FREE QUADLETS
VALID DATA
VALID DATA
FREE QUADLETS
BUFFER DEPTH
BUFFER THRESHOLD
BUFFER DEPTH
BUFFER THRESHOLD
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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...
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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...