MPC5553/MPC5554 Microcontroller Reference Manual, Rev. 5
14-52 Freescale Semiconductor
NOTE
After the software driver has set up the buffers for a frame, it should set up
the corresponding BDs. The last step in setting up the BDs for a transmit
frame should be to set the R bit in the first BD for the frame. The driver
should follow that with a write to TDAR which will trigger the FEC to poll
the next BD in the ring.
14.6 Revision History
Offset + 0 Bit 3 TO2 Transmit software ownership. This field is reserved for use by
software. This read/write bit will not be modified by hardware,
nor will its value affect hardware.
Offset + 0 Bit 4 L Last in frame. Written by user.
0 The buffer is not the last in the transmit frame.
1 The buffer is the last in the transmit frame.
Offset + 0 Bit 5 TC Tx CRC. Written by user (only valid if L = 1).
0 End transmission immediately after the last data byte.
1 Transmit the CRC sequence after the last data byte.
Offset + 0 Bit 6 ABC Append bad CRC. Written by user (only valid if L = 1).
0 No effect
1 Transmit the CRC sequence inverted after the last data byte
(regardless of TC value).
Offset + 0 Bits [7:15] — Reserved.
Offset + 2 Bits [0:15] Data Length Data length, written by user.
Data length is the number of octets the FEC should transmit
from this BD’s data buffer. It is never modified by the FEC. Bits
[0:10] are used by the DMA engine, bits[11:15] are ignored.
Offset + 4 Bits [0:15] A[0:15] Tx data buffer pointer, bits [0:15]
1
Offset + 6 Bits [0:15] A[16:31] Tx data buffer pointer, bits [16:31].
1
The transmit buffer pointer, which contains the address of the associated data buffer, must always be evenly
divisible by 4. The buffer must reside in memory external to the FEC. This value is never modified by the
Ethernet controller.
Table 14-39. Changes to MPC5553/5554 RM for Rev. 4.0 Release
Description of Change
• Changed the FEC signal names. Prepended “FEC_” to all signal names.
Table 14-38. Transmit Buffer Descriptor Field Definitions (Continued)
Halfword Location Field Name Description
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