MB86960 Datasheet, PDF (36/65 Pages) Fujitsu Component Limited. – NETWORK INTERFACE CONTROLLER with ENCODER/DECODER (NICE)

MB86960
Transmit Start Register
The Transmit Start Register, BMPR10, contains the TX
START bit and the TX PKT CNT. Writing 1 to the TX
START bit immediately starts the transmitter. The
Transmit Packet Count is a 7-bit binary integer written
by the host to indicate the number of packets in the
transmit buffer to be transmitted. See Table 14. This
register should only be written when the transmitter is
idle. It can be read at any time. TX START will always
read as 1.
16 Collisions Control Register
This is a command register to control the actions taken
when 16 consecutive attempts to transmit a packet are all
met with collision. Table 15 summarizes the use of this
register. It serves as both a mode setup register and an
action command register. As a mode select register, two
functions are selectable. Firstly, automatic continuation
or halt after 16 collisions can be selected. If automatic
continuation is selected, there is an option to continue
attempting to transmit the same packet, or skip to the next
packet. If halt is enabled, the Transmitter is restarted after
a halt by writing any action code listed in Table 15 to this
register.
DMA Enable Register
This is a write-only register which is used to enable and
clear either Receive Read DMA or Transmit Write DMA.
Refer to Table 14 for the codes.
DMA Burst Register (BMPR13)
This register is used to select the burst length for DMA
operation. The burst length can be 1, 4, 8 or 12 transfers.
Each transfer is one byte or one word, depending on the
mode selected, System Byte or System Word (see SB/SW
in DLCR6).
CODE
00H
01H
02H
03H
No. of Transfers
1
4
8
12
Table 15. 16 Collision Action Codes (written to BMPR11)
ACTION CODE
DESCRIPTION
02H or 03H MODE SETUP: Halt after 16 Collisions.
02H
COMMAND: Resume transmitting, repeat failed packet (for use following a halt). Terminates the halt.
Instructs transmitter to resume transmitting by repeating the failed packet. The collision counter is reset,
allowing up to 16 additional attempts to be made. Halt after 16 collisions.
03H
COMMAND: Resume transmitting, skip failed packet (for use following a halt). Terminates the halt.
Instructs transmitter to skip the failed packet and resume transmitting with the next packet in the buffer. The
collision counter is reset, allowing up to 16 additional attempts to be made. If there is no next packet, the
transmitter will deactivate, setting TX DONE as it does so. Halt after 16 collisions.
06H
MODE SETUP: Continue automatically after 16 collisions, repeat failed packet. Warning: If the network
medium is disconnected, transmission attempts will usually result in false collision detection. Under this
condition, this mode will cause the transmitter to continue re-attempting transmission of the same packet
indefinitely. Interrupt or periodic polling of the status bits should be used to detect this condition.
07H
MODE SETUP: Continue automatically after 16 collisions, skip failed packet. Warning: This mode will
result in failure to transmit some packets, since it skips a packet which has had 16 collisions. This condition
is rare on a healthy network, but it does happen. To avoid this, use mode 06H.
Table 16. DMA Enable Register (BMPR12)
ACTION CODE
DESCRIPTION
01H
Enables Transmit Write DMA
02H
Enables Receive Read DMA
00H
Clear or terminate DMA activity, DMA EOP status bit and associated interrupt, if any. Normally used as
response to End of Process (DMA EOP) interrupt.