SMSC LAN91C111 - Manual (Page 54)

10/100 Non-PCI Ethernet Single Chip MAC + PHY
Datasheet
Revision 1.91 (08-18-08) 54 SMSC LAN91C111 REV C
DATASHEET
Reserved – Must be 0.
8.11 Bank 1 - Configuration Register
The Configuration Register holds bits that define the adapter configuration and are not expected to
change during run-time. This register is part of the EEPROM saved setup.
EPH Power EN - Used to selectively power transition the EPH to a low power mode. When this bit is
cleared (0), the Host will place the EPH into a low power mode. The Ethernet MAC will gate the 25Mhz
TX and RX clock so that the Ethernet MAC will no longer be able to receive and transmit packets. The
Host interface however, will still be active allowing the Host access to the device through Standard IO
access. All LAN91C111 registers will still be accessible. However, status and control will not be allowed
until the EPH Power EN bit is set AND a RESET MMU command is initiated.
NO WAIT - When set, does not request additional wait states. An exception to this are accesses to
the Data Register if not ready for a transfer. When clear, negates ARDY for two to three clocks on
any cycle to the LAN91C111.
GPCNTRL - This bit is a general purpose output port. Its inverse value drives pin nCNTRL and it is
typically connected to a SELECT pin of the external PHY device such as a power enable. It can be
used to select the signaling mode for the external PHY or as a general purpose non-volatile
configuration pin. Defaults low.
EXT PHY – External PHY Enabled.
This bit, when set (1):
a. Enables the external MII.
b. The Internal PHY is disabled and is disconnected (Tri-stated from the internal MII along with any
sideband signals (such as MDINT) going to the MAC Core).
When this bit is cleared (0 - Default):
a. The internal PHY is enabled.
b. The external MII pins, including the MII Management interface pins are tri-stated.
Reserved – Reserved bits.
OFFSET NAME TYPE SYMBOL
0
CONFIGURATION
REGISTER READ/WRITE CR
HIGH
BYTE
EPH
Power
EN
Reserved Reserved NO
WAIT
Reserved GPCNTRL EXT PHY Reserved
1 0 1 0 0 0 0 0
LOW
BYTE
Reserved Reserved Reserved Reserved Reserved Reserved
1 0 1 1 0 0 0 1