DP83905 datasheet(48/80 Pages) NSC

48 / 80 page

60 Operation of ATLANTIC Controller (Continued)

TLF11498 – 30

FIGURE 33 Received Packet Aborted if it Hits Boundary

Enabling the ATLANTIC Controller on an Active

Network

After the ATLANTIC Controller has been initialized the pro-

cedure for disabling and then re-enabling the ATLANTIC

Controller on the network is similar to handling Receive

Buffer Ring overflow as described previously

1 Program Command Register for page 0 (Command

2 Initialize Data Configuration Register (DCR)

3 Clear Remote Byte Count Registers (RBCR0 RBCR1)

if using Remote DMA

4 Initialize Receive Configuration Register (RCR)

5 Place the ATLANTIC Controller in LOOPBACK mode

1 or 2 (Transmit Configuration Register e 02H or 04H)

6 Initialize

Receive

Buffer

Ring

Boundary

Pointer

(BNDRY)

Page Start (PSTART)

and Page Stop

(PSTOP)

7 Clear Interrupt Status Register (ISR) by writing 0FFH to

8 Initialize Interrupt Mask Register (IMR)

9 Program Command Register for page 1 (Command

i) Initialize Physical Address Registers (PAR0 – PAR5)

ii) Initialize

Multicast

Address

Registers

(MAR0 –

MAR7)

iii) Initialize CURRENT pointer

10 Put ATLANTIC Controller in START mode (Command

tive since the ATLANTIC Controller is in LOOPBACK

11 Initialize the Transmit Configuration for the intended

value The ATLANTIC Controller is now ready for

transmission and reception

End of Packet Operations

At the end of the packet the ATLANTIC Controller deter-

mines whether the received packet is to be accepted or

rejected It either branches to a routine to store the Buffer

Header or to another routine that recovers the buffers used

to store the packet

TLF11498 – 31

FIGURE 34 Termination of Received

PacketPacket Accepted

Successful Reception

If the packet is successfully received the DMA is restored

to the first buffer used to store the packet (pointed to by the

Current Page Register) The DMA then stores the Receive

Status a Pointer to where the next packet will be stored

(Buffer 4) and the number of received bytes Note that the

remaining bytes in the last buffer are discarded and recep-

tion of the next packet begins on the next empty 256-byte

buffer boundary The Current Page Register is then initial-

ized to the next available buffer in the Buffer Ring (The

location of the next buffer had been previously calculated

and temporarily stored in an internal scratchpad register)

Buffer Recovery for Rejected Packets

If the packet is a runt packet or contains CRC or Frame

Alignment errors it is rejected The buffer management log-

ic resets the DMA back to the first buffer page used to store

the packet (pointed to by CURR) recovering all buffers that

had been used to store the rejected packet This operation

will not be performed if the ATLANTIC Controller is pro-

grammed to accept either runt packets or packets with CRC

or Frame Alignment errors The received CRC is always

stored in buffer memory after the last byte of received data

for the packet

TLF11498 – 32

FIGURE 35 Termination of Receive

PacketPacket Reject

DP83905 датащи(PDF) 48 Page - National Semiconductor (TI)

DP83905 датащи(HTML) 48 Page - National Semiconductor (TI)

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80

датащи скачать

ссылки URL