LAN9115 datasheet(67/114 Pages) MICROCHIP

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 2005-2016 Microchip Technology Inc.

DS00002269A-page 67

LAN9115

15-7

Reserved

6-5

PHY Clock Select (PHY_CLK_SEL). This field is used to switch between

the internal and external MII clocks (RX_CLK and TX_CLK). This field is

encoded as follows:

[6]

[5]

MII Clock Source

---------------------------------------------------

Internal PHY

External MII Port

Clocks Disabled

Internal PHY

Note:

• This field does not control multiplexing of the SMI port or other MII sig-

nals.

• There are restrictions on the use of this field. Please refer to Section

3.12, "MII Interface - External MII Switching," on page 34 for details.

R/W

00b

Serial Management Interface Select (SMI_SEL). This bit is used to switch

the SMI port (MDIO and MDC) between the internal PHY and the external

MII port. When this bit is cleared to ‘0’, the internal PHY is selected, and all

SMI transactions will be to the internal PHY. When this bit is set to ‘1’, the

external MII port is selected, and all SMI transactions will be to the external

PHY. This bit functions independent of EXT_PHY_EN. When this bit is set,

the internal MDIO and MDC signals are driven low. When this bit is cleared,

the external MIDIO signal is tri-stated, and the MDC signal is driven low.

Note:

This bit does not control the multiplexing of other MII signals.

R/W

External PHY Detect (EXT_PHY_DET). This bit reflects the latched value

of the EXT_PHY_DET strap. The EXT_PHY_DET strap is used to indicate

the presence of an external PHY. This strap is latched from the value of the

external MDIO signal upon power-up or hard reset. If MDIO is pulled high a

‘1’ will be seen in this bit. If MDIO is pulled low a ‘0’ will be seen in this bit.

The RXT_PHY_DET strap has no other effect on the internal logic. Its only

function is to give the system designer a mechanism to indicate the presence

of an external PHY to a software application.

Dependant on

EXT_PHY_D

ET strap pin

External PHY Enable (EXT_PHY_EN). When set to a ‘1’, this bit enables

the external MII port. When cleared, the internal PHY is enabled and the

external MII port is disabled.

Note:

• This signal does not control multiplexing of the SMI port or the TX_CLK

or RX_CLK signals.

• There are restrictions on the use of this bit. Please refer to Section 3.12,

"MII Interface - External MII Switching," on page 34 for details.

Soft Reset Timeout (SRST_TO). If a software reset is attempted when the

internal PHY is not in the operational state (RX_CLK and TX_CLK running), the reset

will not complete and the soft reset operation will timeout and this bit will be set to a

‘1’. The host processor must correct the problem and issue another soft reset.

Bits

Description

Type

Default

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