Sundance Spas ST201 - Manual (Page 31)

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Sundance Technology ST201 PRELIMINARY draft 2
TXFRAMECONTROL
Class....................DMA Data Structures, TFD
Base Address ......Start of TFD
Address Offset .....0x04
Access Mode .......Read/Write
Width ...................32 bits
TxFrameControl contains frame control information for the TxDMA function and the transmit function.
BIT BIT NAME BIT DESCRIPTION
1..0 WordAlign These bits determine the boundary to which transmit frame lengths are
rounded up in the TxFIFO, and transmitted onto the network medium.
00: Align to dword
10: Align to word
X1: Align disabled
9..2 FrameId This field can be used as a frame ID or sequence number. This value is
saved with the frame in the TxFIFO, and made visible in the TxFrameId
register while the frame is being transmitted. When a transmit error
occurs, the driver checks TxFrameId to determine which frame experi-
enced the error.
12..10 Reserved Reserved for future use. Should be set to 0.
13 FcsAppendDisable The host system sets this bit to prevent the ST201 from appending the
4-byte FCS to the end of the current frame. In this case, the host sys-
tem must supply the frame’s FCS as part of the data transferred by
TxDMA to the TxFIFO. An exception exists when a transmit under run
occurs; in this case a guaranteed-bad FCS will be appended to the
frame by the ST201. When FcsAppendDisable is cleared, the ST201
will compute and append FCS to this transmit frame.
14 Reserved Reserved for future use. Should be set to 0.
15 TxIndicate The host system sets this bit to request a TxComplete interrupt upon
completion of MAC transmission of this frame. If TxComplete is
cleared, no interrupt of transmit completion will be given by the ST201,
unless a transmit error occurs.
16 TxDMAComplete Indicates that the frame transfer by TxDMA is complete. The ST201
sets this bit after it has finished transferring via the TxDMA process all
of the fragments specified in the TFD.
30..17 Reserved Reserved for future use. Should be set to 0.
31 TxDMAIndicate Set if the host system desires a TxDMAComplete interrupt upon com-
pletion of TxDMA of this frame. The TFC is read twice by the ST201;
the first time to write the TFC to the TxFIFO before frame data transfer,
and again after the TxDMA operation is complete to test TxDMAIndi-
cate in order to determine whether to generate an interrupt. This allows
the host system time to change TxDMAIndicate while the transfer by
TxDMA is in progress.