Freescale Semiconductor MPC5200B ユーザーズマニュアル
MPC5200B Users Guide, Rev. 1
14-36
Freescale Semiconductor
Initialization Sequence
14.9.3.2
Transmit Frame Control Word
The only requirement for this control word is to have the TC and ABC bits valid. The TC bit defines whether the transmit block should append
the CRC (TC = 1) or not (TC = 0) for the current frame. The ABC bit defines whether the transmit block should append a bad CRC (ABC =
1), independent of the TC value. Refer to
the CRC (TC = 1) or not (TC = 0) for the current frame. The ABC bit defines whether the transmit block should append a bad CRC (ABC =
1), independent of the TC value. Refer to
below for the format of the transmit frame control word.
Bits
Name
Description
0:3
—
Reserved
4
L
Last in Frame, written by the FEC
The buffer is not the last in a frame.
The buffer is the last in a frame.
5:7
Reserved
8
BC
Will be set if the DA is broadcast (FF-FF-FF-FF-FF-FF)
9
MC
Will be set if the DA is multicast and not BC
10
LG
Rx Frame Length Violation, written by the FEC.
A frame length greater than R_CNTRL.MAX_FL was recognized. This bit is valid only if the
L-bit is set. The receive data is not altered in any way unless the length exceeds 2047 bytes.
L-bit is set. The receive data is not altered in any way unless the length exceeds 2047 bytes.
11
NO
Rx Non-octet Aligned Frame, written by the FEC.
A frame that contained a number of bits not divisible by 8 was received and the CRC check that
occurred at the preceding byte boundary generated an error. This bit is valid only if the L-bit is
set. If this bit is set the CR bit will not be set.
occurred at the preceding byte boundary generated an error. This bit is valid only if the L-bit is
set. If this bit is set the CR bit will not be set.
12
Reserved
13
CR
Rx CRC Error, written by the FEC.
This frame contains a CRC error and is an integral number of octets in length. This bit is valid
only if the L-bit is set.
only if the L-bit is set.
14
OV
Overrun, written by the FEC.
A receive FIFO overrun occurred during frame reception. If this bit is set, the other status bits,
M, LG, NO, SH, CR, and CL lose their normal meaning and will be zero. This bit is valid only
if the L-bit is set.
M, LG, NO, SH, CR, and CL lose their normal meaning and will be zero. This bit is valid only
if the L-bit is set.
15
TR
Rx Frame Truncated
Will be set if the receive frame is truncated (frame length > 2047 bytes). If the TR bit is set
the frame should be discarded and the other error bits should be ignored as they may be
incorrect.
the frame should be discarded and the other error bits should be ignored as they may be
incorrect.
16:20
Reserved
21:31
FRAME_
LENGTH
LENGTH
Length of Received Frame
Table 14-44. Transmit Frame Control Word Format
0
1
2
3
4
5
6
7
8
9
0
11
12
13
14
15
TC
ABC
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31