UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
742 of 1269
NXP Semiconductors
UM10503
Chapter 26: LPC43xx Ethernet
26.7.5.2.2
TxDMA 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 the OSF bit is set in DMA Operation
mode register, bit 2). As the transmit process finishes transferring the first frame, it
Fig 72. TxDMA operation in default mode
Start TxDMA
(Re-)fetch next
descriptor
Write status word
to TDES0
Wait for Tx status
Transfer data from
buffer(s)
(AHB)
error?
Own
bit set?
(AHB)
error?
Frame xfer
complete?
Time stamp
present?
(AHB)
error?
Write time stamp to
TDES2 and TDES3
(AHB)
error?
Stop TxDMA
TxDMA suspended
No
Yes
No
Yes
No
No
Start
Yes
Yes
Yes
Close intermediate
descriptor
No
Yes
No
Yes
No
Poll demand