Chapter 11. Ethernet Module
11-21
Programming Model
receive FIFOs. The transmit FIFO uses addresses from X_FSTART to R_FSTART - 4. The
receive FIFO uses addresses from R_FSTART to R_BOUND - 4. The value in this register
must be added to MBAR + 0x800 to determine the absolute address.
R_FSTART needs to be written only to change the default value.
Table 11-17. describes the R_FSTART fields.
11.5.11 Transmit FIFO Watermark (X_WMRK)
The X_WMRK register, shown in Figure 11-14, controls the amount of data required in the
transmit FIFO before transmission of a frame can begin. Setting X_WMRK to larger values
reduces the risk of transmit FIFO underrun due to system bus latency.
31
16
Field
—
Reset
0000_0000_0000_0000
R/W
Read/Write
15
11
10
9
2
1
0
Field
—
1
R-START
—
Reset
0000_0
1
01_0000_00
00
R/W
Read/Write
Addr
MBAR + 0x8D0
Figure 11-13. FIFO Receive Start Register (R_FSTART)
Table 11-17. R_FSTART Field Descriptions
Bits
Name
Description
31–11
—
Reserved, should be cleared.
10
1
Reserved, should be set.
9–2
R_FSTART
Receive FIFO starting address. Address of first receive FIFO location. Acts as delimiter
between receive and transmit FIFOs.
1–0
—
Reserved, should be cleared.
Содержание DigitalDNA ColdFire MCF5272
Страница 1: ...MCF5272UM D Rev 0 02 2001 MCF5272 ColdFire Integrated Microprocessor User s Manual ...
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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 ...