MB86960 Datasheet, PDF (23/65 Pages) Fujitsu Component Limited. – NETWORK INTERFACE CONTROLLER with ENCODER/DECODER (NICE)

MB86960
Type Descriptions (TYPE)
The following legend of descriptions applies to the type
column of the register bit description tables:
R: Readable bit
W: Writeable bit
C: Clears associated status bit and/or interrupt when 1 is
written; no effect when 0 is written
N: Not used; reserved; write only 0 when written
0/1:Initial state after hardware reset
DATA LINK CONTROL REGISTERS
Status and control bits for the transmitter and receiver
sections of the NICE chip are located in the first eight data
link control registers, DLCR0–7. See Tables 4–11 for
details.
Transmit Status Register
This register provides transmit status for the host
processor. The system can enable interrupts based on the
assertion (going high) of bits 7, 2, and/or 1 of this register
by setting the corresponding enable bits in the Transmit
Interrupt Enable register. See Table 4.
Bits 7, 2 and 1 in this register, the bits that can generate
interrupts, are cleared by writing 1 to the bit. Writing 0 to
the bit has no effect, only the NICE chip control logic can
set these bits. Clearing the bit that caused the interrupt will
clear both the bit itself and the interrupt. Since two or
more status conditions can occur at one time, the interrupt
routine must read all of them and act on all of those that are
set.
One method for clearing interrupts is to read the contents
of the status register, then write the same value back to the
register, thus clearing all bits which were set. Another
technique is to clear each status bit separately by writing
its mask to the register. This might be done as the
corresponding interrupt service is performed. Note:
Wholesale clearing of all status bits by writing FFH to the
register is not recommended, since this may clear status
which has just been set and not yet read by the system. The
transmitter must be idle and TX DONE, DLCR0<7>,
must be cleared by writing 1 to it before starting the
transmitter (by writing 1 to TX START, BMPR10<7>).
Table 4. DLCR0 — Transmit Status Register
BIT SYMBOL TYPE
DESCRIPTION
7 TX DONE R TRANSMIT DONE: This bit is set high when all packets in the active transmit buffer have
C been successfully transmitted to the LAN media, or skipped due to excessive collisions. Can
0 generate interrupt if enabled by DLCR2<7>.
6
NET BSY
R NET BUSY: This is a real-time image of the Carrier Sense signal of the receiver.
5
TX-RX
R TRANSMIT PACKET RECEIVED: Indicates that a good packet was received by NICE
0 shortly after transmission was completed. This is used to indicate self-reception of the
packet. This bit is cleared as each transmission begins.
4 CR LOST R CARRIER LOST: This bit is set if the receive carrier sense input is negated during a packet
0 transmission. This can be caused by a collision or a shorted LAN medium. It is automatically
cleared as each transmission begins.
3
0
N RESERVED: Write 0.
0
2
COL
R COLLISION: This bit will assert during transmission of a data packet if a collision occurs on
C the network. The buffer controller will automatically retransmit the current packet after
0 collisions up to 15 times. The user may read the number of consecutive collisions in the
collision counter, DLCR4<7:4>. Can generate interrupt if enabled by DLCR2<2>.
1
16 COL
R 16 COLLISIONS: This bit is set after the sixteenth unsuccessful transmission of the same
C packet. Can generate interrupt if enabled by DLCR2<1>.
0
0
0
R RESERVED: Write 0.
O