SMSC LAN9312 - Manual (Page 137)

High Performance Two Port 10/100 Managed Ethernet Switch with 32-Bit Non-PCI CPU Interface
Datasheet
SMSC LAN9312 137 Revision 1.4 (08-19-08)
DATASHEET
Chapter 10 Serial Management
10.1 Functional Overview
This chapter details the LAN9312 serial management functionality of the I
2
C/Microwire EEPROM
Controller and the supporting EEPROM Loader.
The I 2 C/Microwire EEPROM controller is an I 2 C/Microwire master module which interfaces an optional
external EEPROM with the system register bus and the EEPROM Loader. Multiple types
(I
2
C/Microwire) and sizes of external EEPROMs are supported. Configuration of the EEPROM type
and size are accomplished via the eeprom_type_strap and eeprom_size_strap[1:0] configuration straps
respectively. Various commands are supported for each EEPROM type, allowing for the storage and
retrieval of static data. The I
2
C interface conforms to the Philips I
2
C-Bus Specification .
The EEPROM Loader provides the automatic loading of configuration settings from the EEPROM into
the LAN9312 at reset. The EEPROM Loader module interfaces to the EEPROM Controller, Ethernet
PHYs, and the system CSRs.
10.2 I
2
C/Microwire Master EEPROM Controller
Based on the configuration strap eeprom_type_strap, the I
2
C/Microwire EEPROM controller supports
either Microwire or I
2
C compatible EEPROMs. The I
2
C/Microwire serial management pins functionality
and characteristics differ dependant on the selected EEPROM type as summarized in Table 10.1 .
Note: When the EEPROM Loader is running, it has exclusive use of the I
2
C/Microwire EEPROM
controller. Refer to Section 10.2.4, "EEPROM Loader" for more information.
Table 10.1 I 2 C/Microwire Master Serial Management Pins Characteristics
EEPROM
TYPE/MODE EE_SDA/EEDI PIN EEDO PIN EECS PIN EE_SCL/EECLK PIN
I
2
C Master
EEPROM
Mode
eeprom_type_strap
= 1
EE_SDA
Input enabled
(to I
2
C master)
Open-drain output
(from I
2 C master)
Pull-down disabled
NOT USED
Input enabled
(used for straps)
Output enabled
(driven low)
NOT USED
Input enabled
(used for straps)
Output enabled
(driven low)
EE_SCL
Input enabled
(to I
2
C master and
used for straps)
Open-drain output
(from I
2
C master)
Microwire
Master
EEPROM
Mode
eeprom_type_strap
= 0
EEDI
Input enabled
(to Microwire master)
Output disabled
Pull-down enabled
EEDO
Input enabled
(used for straps)
Output enabled (from
Microwire master)
EECS
Input enabled
(used for straps)
Output enabled (from
Microwire master)
EECLK
Input enabled
(used for straps)
Output enabled (from
Microwire master)