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DS33R11 Ethernet Mapper with Integrated T1/E1/J1 Transceiver
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The MAC circuitry generates a frame status for every frame that is received. This real time status can be read by
SU.RFSB0 to SU.RFSB3. Note the frame status is the “real time” status and hence the value will change as new
frames are received. Hence the real time status reflects the status in time and may not correspond to the current
received frame being processed. This is also true for the transmitted frames.
Frames with errors are usually rejected by the DS33R11. The user has the option of accepting frames by settings
in Receive Frame Rejection Control register (
SU.RFRC). The user can program whether to reject or accept frames
with the following errors:
• MII error asserted during the reception of the frame
• Dribbling bits occurred in the frame
• CRC error occurred
• Length error occurred—the length indicated by the frame length is inconsistent with the number of bytes
received
• Control frame was received. The mode must be full duplex
• Unsupported control frame was received
Note that frames received that are runt frames or frames with collision will automatically be rejected.
Table 9-5. Registers Related to Setting the Ethernet Port
REGISTER NAME FUNCTION
Transmit Frame Resend
Control
SU.TFRC
This register determines if the current frame is retransmitted
due to various transmit errors.
Transmit Frame Status Low
and Transmit Frame Status
High
SU.TFSL and
SU.TFSH
These two registers provide the real-time status of the
transmit frame. Only apply to the last frame transmitted.
Receive Frame Status Byte 0
to 3
SU.RFSB0 to 3
These registers provide the real-time status for the received
frame. Only apply to the last frame received.
Receive Frame Rejection
Control
SU.RFRC
This register provides settings for reception or rejection of
frame based on errors detected by the MAC.
Receiver Maximum Frame
High and Receiver Maximum
Frame Low
SU.RMFSRH and
SU.RMFSRL
The settings for this register provide the maximum size of
frames to be accepted from the MII/RMII receive interface.
MAC Control SU.MACCR This register provides configuration control for the MAC.