DP83916VF National Semiconductor, DP83916VF Datasheet - Page 21

• Manufacturer Part Number: DP83916VF
• Description: IC CTRLR ORIENT NETWK IN 132PQFP
• Manufacturer: National Semiconductor
• Series: SONIC™r

Specifications of DP83916VF

• Controller Type: Network Interface Controller (NIC)
• Interface: Bus
• Mounting Type: Surface Mount
• Package / Case: 132-MQFP, 132-PQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Current - Supply: -
• Voltage - Supply: -
• Operating Temperature: -
• Other names: *DP83916VF

3 0 Buffer Management
3 5 1 1 Transmit Configuration
The TXpkt config field allows the SONIC-16 to be pro-
grammed into one of the transmit modes before each trans-
mission At the beginning of each transmission the SONIC-
16 reads this field and loads the PINTR POWC CRCI and
EXDIS bits into the Transmit Control register (TCR) The
configuration bits in the TCR correspond directly with the
bits in the TXpkt config field as shown in Figure 3-13 See
Section 4 3 4 for the description on the TCR
Note x
3 5 1 2 Transmit Status
At the end of each transmission the SONIC-16 writes the
status bits (
and the number of collisions experienced during the trans-
mission into the TXpkt status field (Figure 3-14 res
served) Bits NC4-NC0 indicate the number of collisions
where NC4 is the MSB See Section 4 3 4 for the descrip-
tion of the TCR
3 5 2 Transmit Buffer Area (TBA)
The TBA contains the fragments of packets that are defined
by the descriptors in the TDA A packet can consist of a
single fragment or several fragments depending upon the
fragment count in the TDA descriptor The fragments also
can reside anywhere within the full 23-bit address range
and be aligned to any byte boundary When an odd byte
boundary is given the SONIC-16 automatically begins read-
ing data at the corresponding word boundary The SONIC-
16 ignores the extraneous bytes which are written into the
PINTR POWC CRCI EXDIS
CRSL
NC4
15
7
X
15
7
e
NC3
FIGURE 3-12 Transmit Descriptor Area
don’t care
14
EXC
6
X
6
k
14
FIGURE 3-13 TXpkt config Field
FIGURE 3-14 TXpkt status Field
10 0
NC2
OWC
13
5
X
l
5
13
) of the Transmit Control Register (TCR)
NC1
12
4
X
res
4
12
NC0
11
PMB
3
X
3
11
X
EXD
10
FU
2
X
(Continued)
2
10
X
TL F 11722– 19
DEF
BCM
9
1
X
1
X
9
NCRS
PTX
e
X
8
0
0
8
X
re-
21
FIFO during odd byte alignment fragments The minimum
allowed fragment size is 1 byte Figure 3-11 shows the rela-
tionship between the TDA and the TBA for single and multi-
fragmented packets
3 5 3 Preparing To Transmit
All fields in the TDA descriptor and the Current Transmit
Descriptor Address (CTDA) register of the SONIC-16 must
be initialized before the Transmit Command (setting the
TXP bit in the Command register) can be issued If more
than one packet is queued the descriptors must be linked
together with the TXpkt link field The last descriptor must
have EOL
To begin transmission the system loads the address of the
first TXpkt status field into the CTDA register Note that the
upper 8-bits of address are loaded in the Upper Transmit
Descriptor (UTDA) register The user performs the following
transmit initialization
1) Initialize the TDA
2) Load the CTDA register with the address of the first
3) Issue the transmit command
Note that if the Source Address of the packet being trans-
mitted is not in the CAM the Packet Monitored Bad (PMB)
bit in the TXpxt status field will be set (see Section 4 3 4)
3 5 3 1 Transmit Process
When the Transmit Command (TXP
register) is issued the SONIC-16 fetches the control infor-
mation in the TDA descriptor loads its appropriate registers
(shown below) and begins transmission (See Section 4 2
for register mnemonics )
TCR
TPS
TFC
TSA0
TSA1
TFS
CTDA
(CTDA is loaded after all fragments have been read and
successfully transmitted If the halt transmit command is is-
sued (HTX bit in the Command register is set) the CTDA
register is not loaded )
During transmission the SONIC-16 reads the packet de-
scriptor in the TDA and transmits the data from the TBA If
TXpkt frag count is greater than one the SONIC-16 after
finishing transmission of the fragment fetches the next
TXpkt frag ptr0 1 and TXpkt frag size fields and transmits
the next fragment This process continues until all frag-
ments of a packet are transmitted At the end of packet
transmission status is written in to the TXpkt status field
The SONIC-16 then reads the TXpkt link field and checks if
EOL
scriptor and transmits the next packet If EOL
IC-16 generates a ‘‘Transmission Done’’ indication in the
Interrupt Status register and resets the TXP bit in the Com-
mand register
In the event of a collision the SONIC-16 recovers its pointer
in the TDA and retransmits the packet up to 15 times The
SONIC-16 maintains a copy of the CTDA register in the
Temporary Transmit Descriptor Address (TTDA) register
The SONIC-16 performs a block operation of 6 3 or 2 ac-
cesses in the TDA depending on where the SONIC-16 is in
the transmit process For the first fragment it reads the
transmit descriptor
e
TXpkt pkt size
TXpkt frag count
TXpkt frag size
0 If it is ‘‘0’’ the SONIC-16 fetches the next de-
TXpkt config
TXpkt frag ptr0
TXpkt frag ptr1
e
TXpkt link
1 and all other descriptors must have EOL
e
1 in the Command
e
1 the SON-
e
0