708
/
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 Signal
RMII Signal
Default
mapping
Remap 1
Remap 2
Remap 3
Pin configuration
COL
-
PA3
Input floating (reset state)
Rx_DV
CRS_DV
PA7
PD8
PA7
PD8
Input floating (reset state)
RxD0
RxD0
PC4
PD9
PC4
PD9
Input floating (reset state)
RxD1
RxD1
PC5
PD10
PC5
PD10
Input floating (reset state)
RxD2
-
PB0
PD11
PB0
PB0
Input floating (reset state)
RxD3
-
PB1
PD12
PB1
PB1
Input floating (reset state)
Rx_ER
-
PB10
Input floating (reset state)
Tx_EN
Tx_EN
PB11
Push-pull alternate output, high speed
(50MHz)
TxD0
TxD0
PB12
Push-pull alternate output, high speed
(50MHz)
TxD1
TxD1
PB13
Push-pull alternate output, high speed
(50MHz)
PPS_OUT
PPS_OUT
PB5
PB6
Push-pull alternate output, high speed
(50MHz)
TxD3
-
PB8
PB7
Push-pull alternate output, high speed
(50MHz)
25.4.3
SMI interface
SMI is used to access and set the configuration of the PHY. It communicates with the external PHY through the clock
line MDC and the data line MDIO, and can access any register of any PHY. SMI interface can support up to 32 PHYs,
but they cannot be accessed at the same time, and only one register of one PHY can be accessed at the same time.
The functions of the clock line MDC and the data line MDIO are as follows:
MDC: Clock signal, the highest frequency is 2.5MHz, in idle state, this pin keeps low level state. When
transmitting data, the minimum holding time of the high level and low level of the signal is 160ns, and the
minimum period of the signal is 400ns;
MDIO: Receive/transmit data with the PHY, and complete the transmission with the clock line MDC.
Figure 25-3 SMI interface signal line
SMI write operation
To implement the SMI write operation, the data to be transmitted needs to be written into the ETH_MACMIIDAT
SMI
PHY
MDC
MDIO