Description
Reset
Type
Name
Bit/Field
Disable Retry
When this bit is set, the MAC attempts only one transmission. When a
collision occurs on the MII interface, the MAC ignores the current frame
transmission and reports a frame abort with excessive collision error in
the transmit frame status.
When this bit is cleared, the MAC attempts retries based on the settings
of the
BL
field (Bits [6:5]).
Note:
This bit is only applicable in half-duplex mode.
Description
Value
MAC retries transmissions based on
BL
bit field.
0
Only one transmission is attempted by the MAC.
1
0x0
RW
DR
9
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
0x0
RO
reserved
8
Automatic Pad or CRC Stripping
When this bit is set, the MAC strips the Pad or Frame Check Sequence
(FCS) field on the incoming frames only if the value of the length field
is less than 1,536 bytes. All received frames with length field greater
than or equal to 1,536 bytes are passed to the application without
stripping the Pad or FCS field.
When this bit is cleared, the MAC passes all incoming frames, without
modifying them, to the Host.
Description
Value
All frames are passed to host unmodified.
0
MAC strips FCS field if value of length field is less than 1,536
bytes.
1
0x0
RW
ACS
7
Back-Off Limit
The Back-Off limit determines the random integer number (r) of slot time
delays (512 bit times for 10/100 Mbps) for which the MAC waits before
rescheduling a transmission attempt during retries after a collision. The
random integer r takes the value in the range 0 <= r < 2
k
The value of k is programmed in the encodings below and is dependent
on the retransmission attempt number, n. This bit is applicable only in
the half-duplex mode.
Description
Value
k= min (n,10), where k is the lowest value when evaluating n or
10.
0x0
k= min (n,8), where k is the lowest value when evaluating n or
8.
0x1
k= min (n,4), where k is the lowest value when evaluating n or
4.
0x2
k= min (n,1), where k is the lowest value when evaluating n or
1.
0x3
0x0
RW
BL
6:5
1475
June 18, 2014
Texas Instruments-Production Data
Tiva
™
TM4C1294NCPDT Microcontroller