DP83901AV National Semiconductor, DP83901AV Datasheet - Page 33

• Manufacturer Part Number: DP83901AV
• Description: IC CONTROLLR SER NETWK IN 68PLCC
• Manufacturer: National Semiconductor

Specifications of DP83901AV

• Controller Type: Serial Network Interface Controller
• Interface: Serial
• Voltage - Supply: 5V
• Current - Supply: 110mA
• Mounting Type: Surface Mount
• Package / Case: 68-LCC (J-Lead)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Operating Temperature: -
• Other names: *DP83901AV

11 0 Initialization Procedures
The SNIC must be initialized prior to transmission or recep-
tion of packets from the network Power on reset is applied
to the SNIC’s reset pin This clears sets the following bits
The SNIC remains in its reset state until a Start Command is
issued This guarantees that no packets are transmitted or
received and that the SNIC remains a bus slave until all
appropriate internal registers have been programmed After
initialization the STP bit of the command register is reset
and packets may be received and transmitted
Initialization Sequence
The following initialization procedure is mandatory
10 Put SNIC in START mode (Command Register
11 Initialize the Transmit Configuration for the intended val-
Before receiving packets the user must specify the location
of the Receive Buffer Ring This is programmed in the Page
Start and Page Stop Registers In addition the Boundary
and Current Page Register must be initialized to the value of
the Page Start Register These registers will be modified
during reception of packets
1 Program Command Register for Page 0 (Command
2 Initialize Data Configuration Register (DCR)
3 Clear Remote Byte Count Registers (RBCR0 RBCR1)
4 Initialize Receive Configuration Register (RCR)
5 Place the SNIC in LOOPBACK mode 1 or 2 (Transmit
6 Initialize Receive Buffer Ring
7 Clear Interrupt Status Register (ISR) by writing 0FFH to
8 Initialize Interrupt Mask Register (IMR)
9 Program Command Register for page 1 (Command
Command Register (CR)
Interrupt Status (ISR)
Interrupt Mask (IMR)
Data Control (DCR)
Transmit Config (TCR)
ue The SNIC is now ready for transmission and recep-
tion
Register
Configuration Register
(BNDRY)
(PSTOP)
it
Register
III) Initialize CURRent pointer
II) Initialize Multicast Address Registers (MAR0– MAR5)
I) Initialize Physical Address Registers (PAR0 – PAR5)
Register
e
e
Page Start (PSTART)
21H)
61H)
e
02H or 04H)
Reset Bits
TXP STA
All Bits
LB1 LB0
Boundary Pointer
and Page Stop
RD2 STP
RST
LAS
Set Bits
e
22H)
33
12 0 Loopback Diagnostics
Three forms of local loopback are provided on the SNIC
The user has the ability to loopback through the deserializer
on the controller through the ENDEC module or the Coax
Transceiver on the DP83901A SNIC Because of the half
duplex architecture of the SNIC loopback testing is a
special mode of operation with the following restric-
tions
Restrictions During Loopback
The FIFO is split into two halves one used for transmission
the other for reception Only 8-bit fields can be fetched from
memory so two tests are required for 16-bit systems to veri-
fy integrity of the entire data path During loopback the maxi-
mum latency from the assertion of BREQ to BACK is 2 0 s
Systems that wish to use the loopback test yet do not meet
this latency can limit the loopback to 7 bytes without experi-
encing underflow Only the last 8 bytes of the loopback
packet are retained in the FIFO The last 8 bytes can be
read through the FIFO register which will advance through
the FIFO to allow reading the receive packet sequentially
When in word-wide mode with Byte Order Select set the
loopback packet must be assembled in the even byte loca-
tion as shown below (The loopback only operated with byte
wide transfers )
When in word-wide mode with Byte Order Select low the
following format must be used for the loopback packet
Note When using loopback in word mode 2n bytes must be programmed in
Destination Address
Source Address
TBCR0 1 Where n
odd location
Length
Data
CRC
e
e
actual number of bytes assembled in even or
(6 Bytes) Station Physical Address
if CRC
e
Appended by SNIC
46 to 1500 Bytes
2 Bytes
e
‘‘0’’ in TCR
l
TL F 10469 – 50
TL F 10469 – 51