Ethernet Bus MII PinOut, Media Independent Interface Description

Ethernet MII Pin Out

Ethernet Bus MII Pin-Out

The Media Independent Interface [MII] is a 40 pin Miniature-D connector. The pinout for the 40 pin D is shown below.
The MII is used to transition between a MAC [Media Access Control] and Ethernet physical devices [PHY].
Pins 2 and pin 3 of the MII interface form the MDIO interface.

**Ethernet MII Pin Out**
Pin Number	Name Signal	Description
1	Power	+5 Vdc/ 3.3 Vdc
2	MDIO	MII Data Input/Output
3	MDC	MII Data Clock
4	RxD 3	Receive Data 3
5	RxD 2	Receive Data 2
6	RxD 1	Receive Data 1
7	RxD 0	Receive Data 0
8	Rx_DV	Rx Data Valid
9	Rx_CLK	Rx Clock
10	Rx_ER	Rx Error
11	Tx_ER	Tx Error
12	Tx_CLK	Tx Clock
13	Tx_EN	Tx Enable
14	TxD 0	Transmit Data 0
15	TxD 1	Transmit Data 1
16	TxD 2	Transmit Data 2
17	TxD 3	Transmit Data 3
18	COL	Collision
19	CRS	Carrier Sense
20	Power	+5 Vdc/ +3.3 Vdc
21	Power	+5 Vdc/ +3.3 Vdc
22	GND	Signal Ground
23	GND	Signal Ground
24	GND	Signal Ground
25	GND	Signal Ground
26	GND	Signal Ground
27	GND	Signal Ground
28	GND	Signal Ground
29	GND	Signal Ground
30	GND	Signal Ground
31	GND	Signal Ground
32	GND	Signal Ground
33	GND	Signal Ground
34	GND	Signal Ground
35	GND	Ground
36	GND	Ground
37	GND	Ground
38	GND	Signal Ground
39	GND	Signal Ground
40	Power	+5 Vdc/ +3.3 Vdc

D-Sub Connector Manufacturers are listed on the Dsub Connector manufacturers page. All other Connector types; Connector manufacturers.

Back to the 10/100 Base Ethernet page, or 1000 base Ethernet page for additional pinout tables and interface descriptions.

Electrical Engineering Design Key words: Ethernet Bus, MII, Interface, Media-independent interface, Physical Layer, Electrical layers, Physical, Mechanical, Type, Description, Brief, specification, Personal Computer, NICK card, CSMA, LAN, IEEE802.3


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