mcf5272 Freescale Semiconductor, Inc, mcf5272 Datasheet - Page 248

• Manufacturer Part Number: mcf5272
• Description: Mcf5272 Coldfire Integrated Microprocessor User
• Manufacturer: Freescale Semiconductor, Inc

Programming Model
Table 11-21 describes the MFLR fields.
11.5.15 Transmit Control Register (TCR)
The TCR register, Figure 11-18, controls the operational mode of the transmit block
11-24
Reset
Reset
Field BRDCAST MULTCAST
Field
Addr
29–24
23–11
R/W
R/W
10–0
Bits
31
30
MULTCAST Multicast address received. Set if the current receive frame contained a multi-cast
BRDCAST
31
15
MAX_FL
HASH
Name
—
Figure 11-17. Maximum Frame Length Register (MFLR)
30
0000_0
Broadcast address received. Set if the current receive frame contained a destination
address of all ones (the broadcast address). Cleared if the current receive frame does not
correspond to a broadcast address.
destination address (the least significant bit of the DA was set). Cleared if the current
receive frame does not correspond to a multi-cast address.
Current hash value. Corresponds to the hash value of the current receive frame’s
destination address. The hash value is a 6-bit field extracted from the least significant
portion of the CRC register.
Reserved, should be cleared.
Maximum frame length. Length is measured starting at DA and includes the CRC at the
end of the frame. Transmit frames longer than MAX_FL cause the BABT interrupt to occur.
Receive frames longer than MAX_FL cause the BABR interrupt to occur and set the LG bit
in the end-of-frame buffer descriptor. Frames exceeding the MAX_FL are not truncated.
Transmit frames are never truncated, but receive frames are truncated at 2k-1 bytes. The
MAX_FL field resets to 1518 decimal and can be programmed either smaller or larger (up
to 2k-1). The recommended default value to be programmed by the user is 1518 or 1522 (if
VLAN Tags are supported).
—
Table 11-21. MFLR Field Descriptions
29
MCF5272 User’s Manual
11
HASH
0000_0000_0000_0000
10
MBAR + 0x948
Read/Write
Read/Write
Description
24
23
101_1110_1110
MAX_FL
—
MOTOROLA
16
0