SMSC LAN9311i - Manual (Page 25)

Two Port 10/100 Managed Ethernet Switch with 16-Bit Non-PCI CPU Interface
Datasheet
SMSC LAN9311/LAN9311i 25 Revision 1.4 (08-19-08)
DATASHEET
2.2.9 GPIO/LED Controller
The LAN9311/LAN9311i provides 12 configurable general-purpose input/output pins which are
controlled via this module. These pins can be individually configured via the GPIO/LED CSRs to
function as inputs, push-pull outputs, or open drain outputs and each is capable of interrupt generation
with configurable polarity. Two of the GPIO pins (GPIO[9:8]) can be used for IEEE 1588 timestamp
functions, allowing GPIO driven 1588 time clock capture when configured as an input, or GPIO output
generation based on an IEEE 1588 clock target compare event.
In addition, 8 of the GPIO pins can be alternatively configured as LED outputs. These pins, GPIO[7:0]
(nP1LED[3:0] and nP2LED[3:0]), may be enabled to drive Ethernet status LEDs for external indication
of various attributes of the switch ports.
2.3 System Configuration
In a typical application, the LAN9311/LAN9311i Host Bus Interface (HBI) is connected to the host
microprocessor/microcontroller via the asynchronous 16-bit interface, allowing access to the
LAN9311/LAN9311i system configuration and status registers. The LAN9311/LAN9311i utilizes the
internal Host MAC to provide a network path for the host CPU. The LAN9311/LAN9311i may share the
host bus with additional system memory and/or peripherals. For more information on the HBI, refer to
Chapter 8, "Host Bus Interface (HBI)," on page 99 .
The 2 Ethernet ports of the LAN9311/LAN9311i must be connected to Auto-MDIX style magnetics for
proper operation on the Ethernet network. Refer to the SMSC Application Note 8.13 “Suggested
Magnetics” for further details.
The LAN9311/LAN9311i also supports optional EEPROM and GPIOs/LEDs. When an EEPROM is
connected, the EEPROM loader can be used to load the initial device configuration from the external
EEPROM via the I
2
C/Microwire interface.
A system configuration diagram of the LAN9311/LAN9311i in a typical embedded environment can be
seen in
Figure 2.2 .
Figure 2.2 System Block Diagram
Magnetics
Magnetics
To Ethernet
To Ethernet
External
25MHz Crystal
Microprocessor/
Microcontroller
GPIOs/LEDs
(optional)
System
Memory
System
Peripherals
EEPROM
(optional)
LAN9311/LAN9311i
I 2 C/Microwire