Altera Cyclone V Device Handbook page 877

17-28
TX DMA Operation: OSF Mode
Figure 17-7: TX DMA Operation in Default Mode
Related Information
TX DMA Operation: Default (Non-OSF) Mode
TX DMA Operation: OSF Mode
While in the Run state, the transmit process can simultaneously acquire two frames without closing the
Status descriptor of the first [if Bit 2 (OSF) in Register 6 (Operation Mode Register) is set]. As the transmit
process finishes transferring the first frame, it immediately polls the transmit descriptor list for the second
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Start
Tx DMA
(Re-)Fetch Next
Descriptor
Error?
no
Poll Demand
no
Tx DMA
Own Bit Set?
Suspended
yes
Transfer Data
from Buffer(s)
Error?
no
Frame
no
Transfer
Complete?
yes
Wait for
Tx Status
Close Intermediate
Descriptor
Timestamp
Present?
no
Write Status
Word to TDES0
no
Error?
Start
Stop
Tx DMA
yes
yes
yes
Write Timestamp
to RDES2 & RDES3
no
Error?
yes
on page 17-26
Ethernet Media Access Controller
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2013.12.30