MOTOROLA
Chapter 17. Fast Ethernet Controller (FEC)
17-27
Programming Model
The RDAR register is cleared at reset and when ECR[ETHER_EN] is cleared.
17.5.4.4 Transmit Descriptor Active Register (TDAR)
The TDAR is a command register which should be written by the user to indicate that the
transmit descriptor ring has been updated (transmit buffers have been produced by the
driver with the ready bit set in the buffer descriptor).
Whenever the register is written, the TDAR bit is set. This value is independent of the data
actually written by the user. When set, the FEC will poll the transmit descriptor ring and
process transmit frames (provided ECR[ETHER_EN] is also set). Once the FEC polls a
transmit descriptor whose ready bit is not set, then the FEC will clear the TDAR bit and
cease transmit descriptor ring polling until the user sets the bit again, signifying additional
descriptors have been placed into the transmit descriptor ring.
The TDAR register is cleared at reset, when ECR[ETHER_EN] is cleared, or when
ECR[RESET] is set.
31
25
24
23
16
Field
—
R_DES_ACTIVE
—
Reset
0000_0000_0000_0000
R/W
R/W
15
0
Field
—
Reset
0000_0000_0000_0000
R/W
R/W
Address
0x1010
Figure 17-6. Receive Descriptor Active
Register (RDAR)
Table 17-14. RDAR Field Descriptions
Bits
Name
Description
31–25
—
Reserved, should be cleared.
24
R_DES_ACTIVE Set to one when this register is written, regardless of the value written.
Cleared by the FEC device whenever no additional “empty” descriptors
remain in the receive ring. Also cleared when ECR[ETHER_EN] is cleared.
23–0
—
Reserved, should be cleared.
Summary of Contents for ColdFire MCF5281
Page 124: ...3 20 MCF5282 User s Manual MOTOROLA EMAC Instruction Set Summary ...
Page 141: ...MOTOROLA Chapter 5 Static RAM SRAM 5 5 SRAM Programming Model ...
Page 142: ...5 6 MCF5282 User s Manual MOTOROLA SRAM Programming Model ...
Page 168: ...6 26 MCF5282 User s Manual MOTOROLA Interrupts ...
Page 186: ...7 18 MCF5282 User s Manual MOTOROLA Functional Description ...
Page 228: ...9 22 MCF5282 User s Manual MOTOROLA Functional Description ...
Page 246: ...10 18 MCF5282 User s Manual MOTOROLA Low Power Wakeup Operation ...
Page 254: ...11 8 MCF5282 User s Manual MOTOROLA Memory Map and Registers ...
Page 264: ...12 10 MCF5282 User s Manual MOTOROLA Chip Select Registers ...
Page 280: ...13 16 MCF5282 User s Manual MOTOROLA Misaligned Operands ...
Page 314: ...14 34 MCF5282 User s Manual MOTOROLA MCF5282 External Signals ...
Page 339: ...MOTOROLA Chapter 15 Synchronous DRAM Controller Module 15 25 SDRAM Example ...
Page 340: ...15 26 MCF5282 User s Manual MOTOROLA SDRAM Example ...
Page 356: ...16 16 MCF5282 User s Manual MOTOROLA DMA Controller Module Functional Description ...
Page 408: ...17 52 MCF5282 User s Manual MOTOROLA Buffer Descriptors ...
Page 446: ...20 24 MCF5282 User s Manual MOTOROLA Interrupts ...
Page 474: ...22 18 MCF5282 User s Manual MOTOROLA Programming Model ...
Page 510: ...23 36 MCF5282 User s Manual MOTOROLA Operation ...
Page 526: ...24 16 MCF5282 User s Manual MOTOROLA I2C Programming Examples ...
Page 672: ...28 12 MCF5282 User s Manual MOTOROLA Functional Description ...
Page 718: ...29 46 MCF5282 User s Manual MOTOROLA Motorola Recommended BDM Pinout ...
Page 750: ...32 8 MCF5282 User s Manual MOTOROLA Ordering Information ...