Sundance-spas ST201 Manual de usuario descargar pdf (Pagina 31)

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

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.

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Sundance-spas ST201 Manual de usuario Pagina 31