
9
P/N:PM0723
REV. 1.0, JUL. 13, 2000
MX98728EC
3.0 Register (Default value is defined after the hardware/power-up reset)
Reset logic : All register bits are cleared by the hardware reset, while the register bit with an "*" in its
symbol name is also cleared by the software reset.
Network Control Register A : NCRA (Reg0h), R/W, default=00h
Bit
0.0
Symbol
RESET
Description
Reset : Software reset. After hardware reset, this bit is 0 meaning normal operation. To
reset GMAC by software, software must write a 1 to this bit first, then followed by writing
a 0 to this bit. After writing a 0 to this bit, GMAC starts normal operation.
Start Transmit Command/Status : Write to issue commands. When done, both bits are
cleared automatically.
0.1
0.2
ST0*
ST1*
Transmit command : ST1 ST0
IDLE state
TX DMA Poll
TX FIFO Send
TX DMA Poll
0 0 Read to indicate TX DMA idle state, write has no effect.
0 1
Start TX DMA, send packets stored in packet memory.
1 0
Immediately send the packet stored in the TX FIFO.
1 1
Start TX DMA, send packets stored in packet memory.
All transmit commands are cleared to 00 when the operation is done to indicate idle
state. When the TX DMA poll and the TX FIFO Send can not be used at the same time.
New packet can be written to the FIFO directly only when ST1, ST0=IDLE and
TXDMA[3:0]=1h. The TX DMA poll and the TX FIFO Send commands can be issued only
when ST1, ST0=IDLE and TXDMA[3:0]=1h, regardless of any error status in previous
transmission.
Start Receive : Enable the MAC to receive packets. Default is disabled.
Loop Back Mode:
LB1
LB0
Mode0
0
0
Normal mode
Mode1
0
1
Internal FIFO Loopback
Mode2
1
0
Internal NWAY Loopback
Mode3
1
1
Internal PMD Loopback
0.3
0.4, 0.5
SR*
LB0*,LB1*
Mode 2 and 3 are reserved for the IC test purpose. Only mode 1 can be used on the
bench. External loopback for the bench can be done by the full duplex normal mode with
the real cable hooked up from the TX port to the RX port.
Interrupt Mode: Set for the active high interrupt, reset for the active low interrupt case.
must be 0 for normal operation.
0.6
0.7
INTMODE
INTCLK