DP83932CVF-20 National Semiconductor, DP83932CVF-20 Datasheet - Page 21

• Manufacturer Part Number: DP83932CVF-20
• Description: IC CTRLR ORIENT NETWORK 132PQFP
• Manufacturer: National Semiconductor
• Series: SONIC™r

Specifications of DP83932CVF-20

• Controller Type: Ethernet Network Interface Controller
• Interface: Bus
• Voltage - Supply: 5V
• Mounting Type: Surface Mount
• Package / Case: 132-MQFP, 132-PQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Current - Supply: -
• Operating Temperature: -
• Other names: *DP83932CVF-20

3 0 Buffer Management
3 5 1 1 Transmit Configuration
The TXpkt config field allows the SONIC to be programmed
into one of the transmit modes before each transmission At
the beginning of each transmission the SONIC reads this
field and loads the PINT 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 writes the status
bits (
the number of collisions experienced during the transmis-
sion 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 32-bit address range
and be aligned to any byte boundary When an odd byte
boundary is given the SONIC automatically begins reading
data at the corresponding word boundary in 16-bit mode or
a long word boundary in 32-bit mode The SONIC ignores
the extraneous bytes which are written into the FIFO during
PINT POWC CRCI EXDIS
CRSL
NC4
15
15
7
X
7
k
e
10 0
NC3
FIGURE 3-12 Transmit Descriptor Area
don’t care
14
EXC
6
X
14
6
l
FIGURE 3-13 TXpkt config Field
FIGURE 3-14 TXpkt status Field
) of the Transmit Control Register (TCR) and
NC2
OWC
13
5
X
13
5
NC1
12
4
X
res
4
12
NC0
11
PMB
3
X
3
11
X
EXD
10
FU
2
X
(Continued)
2
10
X
DEF
BCM
9
1
X
1
TL F 10492– 19
9
X
NCRS
e
PTX
X
8
0
X
0
8
re-
21
odd byte alignment fragments The minimum allowed frag-
ment size is 1 byte Figure 3-11 shows the relationship be-
tween 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 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
begin transmission the system loads the address of the first
TXpkt status field into the CTDA register Note that the up-
per 16-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 6 3 4)
3 5 3 1 Transmit Process
When the Transmit Command (TXP
register) is issued the SONIC fetches the control informa-
tion 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 reads the packet descriptor
in the TDA and transmits the data from the TBA If
TXpkt frag count is greater than one the SONIC after fin-
ishing 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 then reads the TXpkt link field and checks if
EOL
and transmits the next packet If EOL
erates a ‘‘Transmission Done’’ indication in the Interrupt
Status register and resets the TXP bit in the Command reg-
ister
In the event of a collision the SONIC recovers its pointer in
the TDA and retransmits the packet up to 15 times The
SONIC maintains a copy of the CTDA register in the Tempo-
rary Transmit Descriptor Address (TTDA) register
The SONIC performs a block operation of 6 3 or 2 access-
es in the TDA depending on where the SONIC is in the
transmit process For the first fragment it reads the
transmit descriptor
e
e
1 and all other descriptors must have EOL
0 If it is ‘‘0’’ the SONIC fetches the next descriptor
TXpkt pkt size
TXpkt frag count
TXpkt frag size
TXpkt config
TXpkt frag ptr0
TXpkt frag ptr1
TXpkt link
e
e
1 in the Command
1 the SONIC gen-
e
0 To