UM10503
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User manual
Rev. 1.3 — 6 July 2012
708 of 1269
NXP Semiconductors
UM10503
Chapter 26: LPC43xx Ethernet
26.6.32 DMA Status register
The Status register contains all the status bits that the DMA reports to the host. This
register is usually read by the Software driver during an interrupt service routine or polling.
Most of the fields in this register cause the host to be interrupted. The bits in this register
are not cleared when read. Writing 1 to (unreserved) bits in this register (bits [16:0]) clears
them and writing 0 has no effect. Each field (bits[16:0]) can be masked by masking the
appropriate bit in the DMA_INT_EN register.
This fields in this register can be read by the application (Read), can be set to 1 by the
Ethernet core on a certain internal event (Self Set), and can be cleared to 0 by the
application with a register write of 1 (Write Clear). A register write of 0 has no effect on this
field.
Table 565. DMA Transmit descriptor list address register (DMA_TRANS_DES_ADDR,
address 0x4001 1010) bit description
Bit
Symbol
Description
Reset
value
Access
31:0
SRL
Start of transmit list
This field contains the base address of the First Descriptor
in the Transmit Descriptor list. The LSB bit 1 will be ignored
and taken as all-zero by the DMA internally. Hence these
LSB bits are Read Only.
0
R/W
Table 566. DMA Status register (DMA_STAT, address 0x4001 1014) bit description
Bit
Symbol
Description
Reset
value
Access
0
TI
Transmit interrupt
This bit indicates that frame transmission is finished and TDES1[31] is set in the First
Descriptor.
0
R/W
1
TPS
Transmit process stopped
This bit is set when the transmission is stopped.
0
RW
2
TU
Transmit buffer unavailable
This bit indicates that the Next Descriptor in the Transmit List is owned by the host
and cannot be acquired by the DMA. Transmission is suspended. Bits[22:20] explain
the Transmit Process state transitions. To resume processing transmit descriptors,
the host should change the ownership of the bit of the descriptor and then issue a
Transmit Poll Demand command.
0
R/W
3
TJT
Transmit jabber timeout
This bit indicates that the Transmit Jabber Timer expired, meaning that the transmitter
had been excessively active. The transmission process is aborted and placed in the
Stopped state. This causes the Transmit Jabber Timeout TDES0[14] flag to assert.
0
R/W
4
OVF
Receive overflow
This bit indicates that the Receive Buffer had an Overflow during frame reception. If
the partial frame is transferred to application, the overflow status is set in RDES0[11].
0
R/W
5
UNF
Transmit underflow
This bit indicates that the Transmit Buffer had an Underflow during frame
transmission. Transmission is suspended and an Underflow Error TDES0[1] is set.
0
R/W