IP100A LF
Preliminary Data Sheet
65/97
March. 30, 2007
Copyright © 2004, IC Plus Corp.
IP100A LF-DS-R17
11.4.26 TxStatus
Class............................. LAN I/O Registers, Control and Status
Base Address ............... IoBaseAddress register value
Address Offset .............. 0x46
Default .......................... 0x0000
Width ............................ 16 bits
TxStatus returns the status of frame transmission or transmission attempts. TxStatus actually
implements a queue of up to 31 transmit status bytes. A write of an arbitrary value to TxStatus will
advance the queue to the next transmit status byte.
BIT
BIT NAME
R/W
BIT DESCRIPTION
0
Reserved
N/A
Reserved for future use.
1
TxReleaseError
R
Transmit Release Error. If TxReleaseError is a logic 1, a transmit
release error occurred, meaning that the frame transmission
experienced a collision after the front of the frame had already
been released to the transmit FIFO free space. See
TxReleaseThresh register.
2
TxStatusOverflow
R
Transmit Status Overflow. If TxReleaseError is a logic 1, the TxStatus
stack is full and as a result the transmitter has been disabled. Writing
an arbitrary value to TxStatus clears TxReleaseError but the
transmitter must be re-enabled via the TxEnable bit of the
MACCtrl1 register before transmissions may resume.
3
MaxCollisions
R
Maximum Collisions. If MaxCollisions is a logic 1, a frame was not
successfully transmitted due to encountering 16 collisions. The
TxEnable bit of the MACCtrl1 register is used to recover from this
condition. The frame is discarded from the transmit FIFO.
4
TxUnderrun
R
Transmit Underrun. If TxUnderrun is a logic 1 the frame
experienced an under run during the transmit process because
the host system was unable to supply the frame data fast enough
to keep up with the network data rate. An under run will halt the
transmitter and the transmit FIFO. The TxReset bit of the AsicCtrl
register is used to recover from an under run condition.
5
Reserved
N/A
Reserved for future use.
6
TxIndicateReqd
R
Transmit Indicate Requested. If TxIndicateReqd is a logic 1, the
TxIndicate bit of the TxFrameControl field for the corresponding
TFD was set.
7
TxComplete
R
Transmit Complete. If TxComplete is a logic 0, then the
TxReleaseError, TxStatusOverflow, MaxCollisions, TxUnderrun,
and TxIndicateReqd bits are undefined. If the host chooses to poll
TxStatus while waiting for a frame transmission to complete, then
TxComplete is used to determine that a frame transmission
attempt has either experienced an error, or has completed
successfully with the TxIndicate bit set in the TxFrameControl
field of the corresponding TFD.
15..8
TxFrameId
R/W
Transmit Frame Identification. TxFrameId contains the value from
the FrameId subfield within the TxFrameControl field of TFD
corresponding to the currently transmitting or most recently
transmitted frame. Host systems can use TxFrameId during
transmit error recovery by scanning through the TFD’s in the
transmit DMA list, searching for a match between the TxFrameId
value and a TxFrameControl’s, FrameId value in the TFD.
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