Altera cyclone V Technical Reference page 1169

16-18
Example Program for DMAC Length Management
Program the
peripheral request interface receives any request type.
• Single— If the head entry in the request FIFO buffer is a single request type, the DMAC pops the entry
from the FIFO buffer and continues program execution.
• Burst—If the head entry in the request FIFO buffer is a burst request type, the DMAC leaves the entry
in the FIFO buffer and continues program execution.
Note: The burst request entry remains in the request FIFO buffer until the DMAC executes a
burst instruction or a
Program the
peripheral request interface receives a burst request.
• Single—If the head entry in the request FIFO buffer is a single request type, the DMAC removes the
entry from the FIFO buffer and continues program execution.
• Burst—If the head entry in the request FIFO buffer is a burst request type, the DMAC pops the entry
from the FIFO buffer and continues program execution.
Program the
peripheral when it completes the AXI read transfers. Similarly, use the
require the DMAC to send an acknowledgment to the peripheral when it completes the AXI write
transfers. The DMAC uses the acknowledge bus to signal a transfer acknowledgment to the peripheral.
Note: The DMAC sends an acknowledgment for a read transaction when the
are high and for a write transaction when
acknowledgment to the peripheral while the transfer of write data to the end destination is still in
progress.
Use the
DMAFLUSHP
the DMAC executes
request. This protocol enables the DMAC and peripheral to synchronize with each other.
Example Program for DMAC Length Management
This example shows a DMAC program that can transfer 1027 words when a peripheral signals 16 consecu‐
tive burst requests and three consecutive single requests.
Example 16-2: DMAC Length Management Program
# Set up for AXI burst transfer (4-beat burst, so SB4 and DB4), (word data
width, so SS32 and DS32)
DMAMOV CCR SB4 SS32 DB4 DS32
DMAMOV SAR ...
DMAMOV DAR ...
# Initialize peripheral '0'
DMAFLUSHP P0
# Perform peripheral transfers
# Burst request loop to transfer 1024 words
DMALP 16
# Wait for the peripheral to signal a burst request. DMAC transfers 64 words
for each burst request
DMAWFP 0, burst
# Set up loop for burst request: first 15 of 16 sets of transactions
DMALP 15
DMALD
DMAST
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single instruction when you require the program thread to halt execution until the
DMAWFP
DMAFLUSHP
burst instruction when you require the program thread to halt execution until the
DMAWFP
instruction when you require the DMAC to send an acknowledgment to the
DMALDP
instruction to reset the request FIFO buffer for the peripheral request interface. After
, it ignores peripheral requests until the peripheral acknowledges the flush
DMAFLUSHP
instruction.
signal is high. The DMAC might send an
bvalid
instruction when you
DMASTP
and
rvalid rlast
DMA Controller
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cv_5v4
2016.10.28
DMAWFP
signals