LH79524/LH79525 User’s Guide
Ethernet MAC Controller
Version 1.0
6-25
6.3.2.4 Transmit Status Register (TXSTATUS)
This register provides transmit status details. Individual bits may be cleared by writing 1 to
them. It is not possible to program a bit to 1 by writing to the register.
Table 6-12. TXSTATUS Register
BIT
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
FIELD
///
RESET
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
TYPE
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
BIT
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
FIELD
///
TXUND
ER
TXC
O
MPLET
E
BUFEX
TXG
O
RETRYLIMIT
C
O
LLISION
USEDBIT
RESET
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
TYPE
RO
RO
RO
RO
RO
RO
RO
RO
RO
RW
RW
RW
RO
RW
RW
RW
ADDR
0xFF 0x14
Table 6-13. TXSTATUS Fields
BITS
NAME
FUNCTION
31:7
///
Reserved
Reading returns 0. Write the reset value.
6
TXUNDER
Transmit Underrun
This bit shows when transmit DMA was not able
to read data from the buffer in system memory. The cause can be that
the AHB or ASB bus was not granted in time, a ‘Not OK’ response was
returned, a zero length buffer was read, or because a Used bit was read
midway through frame transmission. If this happens, the transmitter forc-
es a bad CRC and the Transmit Error (ETHERTXER) pin HIGH.
Read:
1 = DMA Unable to read data from memory
0 = Normal operation
Write:
1 = Reset bit to 0
0 = No effect
5
TXCOMPLETE
Transmit Complete
Advises when a frame has been transmitted.
Read:
1 = Frame transmission complete
0 = Frame transmission not complete
Write:
1 = Reset bit to 0
0 = No effect