LAN91C95 datasheet(85/144 Pages) SMSC

85 / 144 page

TYPICAL FLOW OF EVENTS FOR TRANSMIT

S/W DRIVER

CSMA/CD SIDE

ISSUE ALLOCATE MEMORY FOR TX - N

BYTES - the MMU attempts to allocate N bytes

of RAM.

WAIT

FOR

SUCCESSFUL

COMPLETION

CODE - Poll until the ALLOC INT bit is set or

enable its mask bit and wait for the interrupt.

The TX packet number is now at the Allocation

Result Register.

LOAD TRANSMIT DATA - Copy the TX packet

number into the Packet Number Register.

Write the Pointer Register, then use a block

move operation from the upper layer transmit

queue into the Data Register.

ISSUE "ENQUEUE PACKET NUMBER TO TX

FIFO" - This command writes the number

present in the Packet Number Register into the

TX FIFO. The transmission is now enqueued.

No further CPU intervention is needed until a

transmit interrupt is generated.

The enqueued packet will be transferred to the

CSMA/CD block as a function of TXENA (n

TCR) bit and of the deferral process (in half

duplex mode) state.

Upon transmit completion the first word in

memory is written with the status word. The

packet number is moved from the TX FIFO into

the TX completion FIFO. Interrupt is generated

by the TX completion FIFO being not empty.

SERVICE INTERRUPT - Read Interrupt Status

Done Packet Number from the FIFO Ports

Packet Number Register.

The corresponding

status word is now readable from memory. If

the status word shows successful transmission,

issue RELEASE packet number command to

free up the memory used by this packet.

Remove packet number from completion FIFO

by writing TX INT Acknowledge Register.

LAN91C95 Datasheet(PDF) 85 Page - SMSC Corporation

LAN91C95 Datasheet(HTML) 85 Page - SMSC Corporation

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 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL