711
/
838
Nations Technologies Inc.
Tel
:
+86-755-86309900
:
Address: Nations Tower, #109 Baoshen Road, Hi-tech Park North.
Nanshan District, Shenzhen, 518057, P.R.China
MII_COL: Collision detection signal, controlled by PHY, only works in half-duplex mode. This signal is enabled
when a medium collision is detected and remains active for the duration of the collision. This signal does not
need to be synchronized with the transmit/receive clock.
Table 25-3 Transmit interface signal code
MII_Tx_EN
MII_TxD[3:0]
Explanation
0
0000 to 1111
Normal frame interval
1
0000 to 1111
Normal data transfer
Table 25-4 Receive interface signal code
MII_Rx_DV
MII_Rx_ERR
MII_RxD[3:0]
Explanation
0
0
0000 to 1111
Normal frame interval
0
1
0000
Normal frame interval
0
1
0001 to 1101
Reserved
0
1
1110
Wrong carrier indication
0
1
1111
Reserved
1
0
0000 to 1111
Normal data receive
1
1
0000 to 1111
Error receiving data
MII clock source
External PHY module needs an external 25MHz clock drive to generate the Tx_CLK and Rx_CLK clock signals.
External 25MHz clock can be different from the MAC clock. Can use an external 25MHz crystal oscillator or
configure the appropriate PLL to make the MCU clock output the 25MHz clock provided by the MCO pin.
Figure 25-5 MII clock source
25.4.5
RMII interface
The RMII specification reduces the number of pins required for communication. The IEEE802.3 standard stipulates
that the MII interface requires 16 pins for data and control signals, while the RMII standard reduces the number of
pins to 7.
MCO
HSE
M
A
C
8
0
2
.3
25 MHz
PHY
25 MHz
25 MHz
Tx_CLK
Rx_CLK
N32G45x