Analog Devices SHARC ADSP-214 Series Hardware Reference Manual page 405

the local channel buffer memory is 124 quadlets. At reset each channel has
four quadlets each.
BUFFER THRESHOLD
TX DATA
INPUT
VALID DATA
(NUMBER OF VALID DATA QUADLETS <= BUFFER THRESHOLD)
RX DATA
OUTPUT
VALID DATA
Figure 8-2. Local Channel Buffer Threshold Mechanism
The buffer depth, buffer threshold and buffer start address for each chan-
nel is programmed using the respective
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 <=
ADSP-214xx SHARC Processor Hardware Reference
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TRANSMIT SERVICE REQUEST GENERATED
BUFFER DEPTH
RECEIVE SERVICE REQUEST GENERATED
(NUMBER OF FREE DATA QUADLETS <= BUFFER THRESHOLD)
MLB_LCBCRx
BUFFER DEPTH
FREE QUADLETS
BUFFER THRESHOLD
FREE QUADLETS
register. The buffer
MLB_LCBCRx
(programmed using
Media Local Bus
TX DATA
OUTPUT
RX DATA
INPUT
bits)
TH
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