S3C2500B
ETHERNET CONTROLLER
7-15
7.4.1 BDMA RELATIVE SPECIAL REGISTER
7.4.1.1 Buffered DMA Transmit Control Register
Table 7-4. BDMATXCON Register
Registers
Address
R/W
Description
Reset Value
BDMATXCONA
0xF00A0000
R/W
Buffered DMA transmit control register
0x00000000
BDMATXCONB
0xF00C0000
R/W
Buffered DMA transmit control register
0x00000000
Table 7-5. BDMA Transmit Control Register Description
Bit Number
Bit Name
Description
[3:0]
BDMA Tx Number of Buffer
Descriptor (BTxNBD)
You can select number of buffer descriptor.
0000 = 2
0
, 0001 = 2
1
, 0010 = 2
2
,….., 11xx = 2
12
[6:4]
BDMA transmit to MAC Tx
start level (BTxMSL)
These bits determine when to move the data of the new frame in
the BDMA Tx Buffer (BTxBUFF) to the MAC TxFIFO (MTxFIFO)
at a new frame arrival.
000 means no wait, 001 means wait to fill 1/8 of the BDMA Tx
Buffer, 010 means wait to fill 2/8 of the buffer, and so on through
100, which means wait to fill 4/8 of the BDMA Tx Buffer.
NOTE:
If the last data of the frame arrives in BDMA Tx Buffer,
the data transfer from the BDMA Tx Buffer to the MAC
TxFIFO starts immediately, regardless of the level of
these bits.
[7]
Tx Byte Swapping
(BTxBSWAP)
Use to prevent disorder of byte sequence when memory operate
on big-endian format and byte unit access.
If this bit is set, the transferring byte is swapped.
(B3,B2,B1,B0)
à
(B0,B1,B2,B3)
[8]
Reserved
Not applicable.
[9]
–
Factorial test bit
[10]
BDMA Tx enable (BTxEn)
When the Tx enable bit is set to ‘1’, the BDMA Tx block is
enabled. Even if this bit is disabled, buffer data will be moved to
the MAC TxFIFO until the BDMA TxBUFF underflows.
This bit is automatically cleared when the BDMA is not the owner.
NOTE:
The BDMATXDPTR register must be assigned before this
bit is set.
[11]
BDMA Tx reset (BTxRS)
Set this bit to ‘1’ to reset the BDMA Tx block.
[31:12]
Reserved
Содержание S3C2500B
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Страница 531: ...GDMA CONTROLLER S3C2500B 12 24 NOTES ...
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