SMSC LAN91C111 32/16/8-Bit Three-In-One Fast Ethernet Controller
SMSC AN 9.6 3 Revision 1.0 (08-14-08)
APPLICATION NOTE
3 Description Of Bus Interface Unit (BIU)
This section is intended to aid design engineers connecting the SMSC LAN91C111 device to a
microprocessor or microcontroller. This section will discuss in detail the functional block, and the
individual control signals of the LAN91C111 involved in the connection between the device and an
associated microprocessor / microcontroller.
3.1 Pin Function Listing
The LAN91C111 consist of the following major pin groups:
The interfacing of the LAN91C111 is based on the use of the control lines to control the flow of
information to and from the controller. The LAN91C111 is designed with the flexibility required to allow
a design engineer to connect the LAN91C111 to just about any standard microprocessor architecture.
This document should provide a design engineer the information needed to connect the LAN91C111
to the microprocessor or microcontroller of their choice.
PIN DESCRIPTION NUMBER OF PINS USED
System Address Pins 20
System Data Pins 32
System Control Pins 14
Serial EEPROM Pins 8
LED Pins 2
PHY Pins 8
Crystal Oscillator 2
Power Pins 10
Ground Pins 12
MII Connection Pins 18
Misc. Pins 2
