
E T H E R N E T C O M M U N I C A T I O N M O D U L E
Transmit packet processor
270
Hardware Reference NS9215
reside in different buffers in system memory, several buffer descriptors can be used
to transfer the frame.
Transmit buffer
descriptor format
All buffer descriptors (that is, up to 64) are found in a local TX buffer descriptor
RAM. This is the transmit buffer descriptor format.
Transmit buffer
descriptor field
definitions
Destination Address (not used)
Buffer Length (11-bits used)
Status
Source Address
0
0
4
8
C
F
I
L
W
Reserved
31
15
16
30 29 28
Field
Description
W
WRAP
bit, which, when set, tells the
TX_WR
logic that this is the last buffer descriptor
within the continuous list of descriptors in the TX buffer descriptor RAM. The next
buffer descriptor is found using the initial buffer descriptor pointer in the TX Buffer
Descriptor Pointer register (TXPTR).
When the
WRAP
bit is not set, the next buffer descriptor is located at the next entry
in the TX buffer descriptor RAM.
I
When set, tells the
TX_WR
logic to set
TXBUFC
in the Ethernet Interrupt Status
register when the buffer is closed due to a normal channel completion.
Buffer pointer
32-bit pointer to the start of the buffer in system memory. This pointer can be aligned
on any byte of a 32-bit word.
Status
Lower 16 bits of the Ethernet Transmit Status register. The status is returned from
the Ethernet MAC at the end of the frame and written into the last buffer descriptor
of the frame.
L
When set, tells the
TX_WR
logic that this buffer descriptor is the last descriptor that
completes an entire frame. This bit allows multiple descriptors to be chained together
to make up a frame.
Содержание NS9215
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Страница 44: ...P I N O U T 26 5 System clock 44 Hardware Reference NS9215 System clock drawing...
Страница 52: ...P I N O U T 26 5 Power and ground 52 Hardware Reference NS9215...
Страница 80: ...I O C O N T ROL M O D U L E Memory Bus Configuration register 80 Hardware Reference NS9215...
Страница 136: ...WOR KI N G W I TH T H E C P U Noncachable instruction fetches 136 Hardware Reference NS9215...
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Страница 260: ...M E MO R Y C O N T ROL L E R StaticMemory Turn Round Delay 0 3 registers 260 Hardware Reference NS9215...
Страница 354: ...E X T E R N A L D M A DMA Peripheral Chip Select register 354 Hardware Reference NS9215...
Страница 362: ...A E S D AT A E N C R Y P T I O N D E C R Y P T I O N M O D U L E CCM mode 362 Hardware Reference NS9215...
Страница 384: ...I O HU B M OD UL E Module Direct Mode TX Data Last FIFO 384 Hardware Reference NS9215 31 March 2008...
Страница 414: ...S E R I A L C ON T RO L M O D U L E U ART UART Modem Status register 414 Hardware Reference NS9215...
Страница 446: ...S E R I A L C ON T RO L M O D U L E S PI SPI timing characteristics 446 Hardware Reference NS9215...
Страница 472: ...R E A L TI M E C L O C K M O D U L E General Status register 472 Hardware Reference NS9215...
Страница 512: ...TI M I NG Clock timing 512 Hardware Reference NS9215...
Страница 514: ...PA CKA GING Processor Dimensions 514 Hardware Reference NS9215 P r o c e s s o r D i m e n s i o n s...
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