DP83936AVUL-20 National Semiconductor, DP83936AVUL-20 Datasheet - Page 32

• Manufacturer Part Number: DP83936AVUL-20
• Description: IC CTRLR ORIENT NETWORK 160PQFP
• Manufacturer: National Semiconductor

Specifications of DP83936AVUL-20

• Controller Type: Network Interface Controller (NIC)
• Interface: Twisted Pair
• Voltage - Supply: 4.75 V ~ 5.25 V
• Current - Supply: 140mA
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 160-MQFP, 160-PQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: *DP83936AVUL-20

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14 See Section 6 4 4 for the description on the TCR
5 0 Buffer Management
5 5 1 1 Transmit Configuration
The TXpkt config field allows the SONIC-T to be pro-
grammed into one of the transmit modes before each trans-
mission
SONIC-T 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 5-
Note x
5 5 1 2 Transmit Status
At the end of each transmission the SONIC-T writes the
status bits (
and the number of collisions experienced during the trans-
mission into the TXpkt status field ( Figure 5-15 res
served) Bits NC4 –NC0 indicate the number of collisions
where NC4 is the MSB See Section 6 4 4 for the descrip-
tion of the TCR
5 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-T automatically begins read-
ing data at the corresponding word boundary in 16-bit mode
or a long word boundary in 32-bit mode The SONIC-T ig-
PINTR POWC CRCI EXDIS
NC4
CRSL
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15
X
15
7
7
e
NC3
FIGURE 5-13 Transmit Descriptor Area
don’t care
14
EXC
At the beginning of each transmission
X
6
6
k
14
FIGURE 5-14 TXpkt config Field
FIGURE 5-15 TXpkt status Field
10 0
NC2
OWC
13
X
5
l
5
13
) of the Transmit Control Register (TCR)
NC1
12
X
4
res
4
12
NC0
PMB
11
X
3
3
11
X
EXD
10
FU
X
2
(Continued)
2
10
X
DEF
BCM
9
X
1
1
TL F 12597–24
9
X
NCRS
PTX
e
X
8
0
0
X
8
the
re-
32
nores the extraneous bytes which are written into the FIFO
during odd byte alignment fragments The minimum allowed
fragment size is 1 byte Figure 5-12 shows the relationship
between the TDA and the TBA for single and multi-frag-
mented packets
5 5 3 Preparing To Transmit
All fields in the TDA descriptor and the Current Transmit
Descriptor Address (CTDA) register of the SONIC-T 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
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 trans-
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 4 4)
5 5 3 1 Transmit Process
When the Transmit Command (TXP
register) is issued the SONIC-T fetches the control informa-
tion in the TDA descriptor loads its appropriate registers
(shown below) and begins transmission (See Section 6 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-T reads the packet descrip-
tor in the TDA and transmits the data from the TBA If
TXpkt frag count is greater than one the SONIC-T 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-T then reads the TXpkt link field and checks if
EOL
tor and transmits the next packet If EOL
generates 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-T recovers its pointer
in the TDA and retransmits the packet up to 15 times The
SONIC-T maintains a copy of the CTDA register in the Tem-
porary Transmit Descriptor Address (TTDA) register
e
mit descriptor
1 and all other descriptors must have EOL
e
0 If it is ‘‘0’’ the SONIC-T fetches the next descrip-
TXpkt pkt size
TXpkt frag size
TXpkt frag count
TXpkt config
TXpkt frag ptr0
TXpkt frag ptr1
TXpkt link
e
1 in the Command
e
1 the SONIC-T
e
0 To begin