11-24
MCF5272 User’s Manual
Programming Model
11.5.14 Maximum Frame Length Register (MAX_FRM_LEN)
As shown in Figure 11-17, the MAX_FRM_LEN register serves two purposes. Bits 10–0
provide the user R/W MAX_FL field. The MAX_FL field allows the user to program the
maximum legal-size frame. Frames larger than this size cause the BABT interrupt (transmit
frames) or BABR interrupt and receive buffer descriptor LG bit to be asserted (receive
frames). Frames exceeding the MAX_FL are not truncated.
Bits 31–24 provide an eight-bit read-only field that provides address recognition
information from the receive block about the frame currently being received by the FEC.
Table 11-21. describes the MAX_FRM_LEN fields.
Table 11-20. R_CNTRL Field Descriptions
Bits
Name
Description
31–4
—
Reserved, should be cleared.
3
PROM
Promiscuous mode. All frames are accepted regardless of address matching.
2
MII_MODE
MII mode enable. Selects the external interface mode. Setting this bit to one
selects MII mode, setting this bit equal to zero selects seven-wire mode (used
only for serial 10 Mbps). This bit controls the interface mode for both transmit and
receive blocks.
1
DRT
Disable receive on transmit
0 Receive path operates independently of transmit (use for full duplex or to
monitor transmit activity in half-duplex mode).
1 Disable reception of frames while transmitting (normally used for half-duplex
mode).
0
LOOP
Internal loopback. If set, transmitted frames are looped back internal to the FEC
and the transmit output signals are not asserted. The system clock is substituted
for the E_TxCLK when LOOP is asserted. DRT must be set to zero when
asserting LOOP.
31
30
29
24
23
16
Field BRDCAST MULTCAST
HASH
—
Reset
0000_0000_0000_0000
R/W
Read/Write
15
11
10
0
Field
—
MAX_FL
Reset
0000_0
101_1110_1110
R/W
Read/Write
Addr
MBAR + 0x948
Figure 11-17. Maximum Frame Length Register (MAX_FRM_LEN)
Содержание DigitalDNA ColdFire MCF5272
Страница 1: ...MCF5272UM D Rev 0 02 2001 MCF5272 ColdFire Integrated Microprocessor User s Manual ...
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Страница 58: ...1 10 MCF5272 User s Manual MCF5272 Specific Features ...
Страница 90: ...2 42 MCF5272 User s Manual Exception Processing Overview ...
Страница 96: ...3 6 MCF5272 User s Manual MAC Instruction Execution Timings ...
Страница 158: ...5 46 MCF5272 User s Manual Motorola Recommended BDM Pinout ...
Страница 184: ...7 12 MCF5272 User s Manual Interrupt Controller Registers ...
Страница 338: ...13 44 MCF5272 User s Manual Application Examples ...
Страница 414: ...18 6 MCF5272 User s Manual PWM Programming Model ...
Страница 452: ...19 38 MCF5272 User s Manual Power Supply Pins ...
Страница 482: ...20 30 MCF5272 User s Manual Reset Operation ...
Страница 492: ...21 10 MCF5272 User s Manual Non IEEE 1149 1 Operation ...
Страница 548: ...INDEX Index 12 MCF5272 User s Manual ...