DP8390 NSC [National Semiconductor], DP8390 Datasheet - Page 29

• Manufacturer Part Number: DP8390
• Description: NIC Network Interface Controller
• Manufacturer: NSC [National Semiconductor]

10 0 Internal Registers
If address Y is found to hash to the value 32 (20H) then
FB32 in MAR4 should be initialized to ‘‘1’’ This will cause
the NIC to accept any multicast packet with the address Y
NETWORK TALLY COUNTERS
Three 8-bit counters are provided for monitoring the number
of CRC errors Frame Alignment Errors and Missed Pack-
ets The maximum count reached by any counter is 192
(C0H) These registers will be cleared when read by the
CPU The count is recorded in binary in CT0–CT7 of each
Tally Register
Frame Alignment Error Tally (CNTR0)
This counter is incremented every time a packet is received
with a Frame Alignment Error The packet must have been
recognized by the address recognition logic The counter is
cleared after it is read by the processor
CRC Error Tally (CNTR1)
This counter is incremented every time a packet is received
with a CRC error The packet must first be recognized by
the address recognition logic The counter is cleared after it
is read by the processor
Frames Lost Tally Register (CNTR2)
This counter is incremented if a packet cannot be received
due to lack of buffer resources In monitor mode this coun-
ter will count the number of packets that pass the address
recognition logic
FIFO
This is an eight bit register that allows the CPU to examine
the contents of the FIFO after loopback The FIFO will con-
tain the last 8 data bytes transmitted in the loopback packet
Sequential reads from the FIFO will advance a pointer in the
FIFO and allow reading of all 8 bytes
Note The FIFO should only be read when the NIC has been programmed in
MAR0 FB7
MAR1 FB15 FB14 FB13 FB12 FB11 FB10 FB9
MAR2 FB23 FB22 FB21 FB20 FB19 FB18 FB17 FB16
MAR3 FB31 FB30 FB29 FB28 FB27 FB26 FB25 FB24
MAR4 FB39 FB38 FB37 FB36 FB35 FB34 FB33 FB32
MAR5 FB47 FB46 FB45 FB44 FB43 FB42 FB41 FB40
MAR6 FB55 FB54 FB53 FB52 FB51 FB50 FB49 FB48
MAR7 FB63 FB62 FB61 FB60 FB59 FB58 FB57 FB56
CNTR0 CT7 CT6 CT5 CT4 CT3 CT2 CT1 CT0
CNTR1 CT7 CT6 CT5 CT4 CT3 CT2 CT1 CT0
CNTR2 CT7 CT6 CT5 CT4 CT3 CT2 CT1 CT0
FIFO DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
loopback mode
D7
7
7
7
7
FB6
D6
6
6
6
6
FB5
D5
5
5
5
5
FB4
D4
4
4
4
4
FB3
D3
3
3
3
3
(Continued)
FB2
D2
2
2
2
2
FB1
D1
1
1
1
1
FB0
FB8
D0
0
0
0
0
29
NUMBER OF COLLISIONS (NCR)
This register contains the number of collisions a node expe-
riences when attempting to transmit a packet If no colli-
sions are experienced during a transmission attempt the
COL bit of the TSR will not be set and the contents of NCR
will be zero If there are excessive collisions the ABT bit in
the TSR will be set and the contents of NCR will be zero
The NCR is cleared after the TXP bit in the CR is set
11 0 Initialization Procedures
The NIC must be initialized prior to transmission or recep-
tion of packets from the network Power on reset is applied
to the NIC’s reset pin This clears sets the following bits
The NIC remains in its reset state until a Start Command is
issued This guarantees that no packets are transmitted or
received and that the NIC remains a bus slave until all ap-
propriate 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 NIC in START mode (Command Register
11) Initialize the Transmit Configuration for the intended val-
NCR
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 NIC 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)
Register
Configuration Register
(BNDRY)
(PSTOP)
it
Register
i)Initialize Physical Address Registers (PAR0-PAR5)
ii)Initialize Multicast Address Registers (MAR0-MAR7)
iii)Initialize CURRent pointer
The local receive DMA is still not active since the NIC is
in LOOPBACK
ue The NIC is now ready for transmission and recep-
tion
7
Register
e
e
Page Start (PSTART)
6
21H)
61H)
5
e
4
02H or 04H)
Reset Bits
TXP STA
LB1 LB0
All Bits
NC3 NC2 NC1 NC0
3
Boundary Pointer
and Page Stop
2
RD2 STP
Set Bits
1
RST
LAS
e
22H)
0