Intel EP80579 Guide

Intel
®
EP80579 Integrated Processor Product Line May 2010
Order Number: 320068-005US 238
Local Expansion Bus (LEB) Interface—Intel
®
EP80579 Integrated Processor Product Line
22.2 LEB Memory Size (LEB_SIZE) Strapping
As stated above, the LEB controller allocates up to 256 MB of memory space to support
up to 8 devices on the LEB Bus. At power-up or whenever RESET_IN# is asserted,
EX_ADDR[23:21] bits are captured and stored by the LEB controller to detemine the
LEB memory size (LEB_SIZE) and the number of devices supported on the bus. The
EX_ADDR[23:21] should be externally strapped with 1K ohm pull-ups and pull-downs
to determine the LEB_SIZE as shown in Table 87.
22.3 LEB Interface Topologies
There are three groups of signals that require careful routing when designing with the
LEB interface. These groups are split into Chip Select, Address, and Data/Control
signals. The following sections recommend guidelines to help design a working system
that will minimize signal integrity issues. The recommendations are based on the
Development Board routing with the LEB clock rate at 33 MHz.
22.3.1 LEB Interface Topology at 33 MHz
The Development Board has been designed to interface with up to 7 devices, which are
split in two bridges. The primary bridge interconnects with the first four peripherals and
a buffer, while the secondary bridge interconnects with three mezzanine connectors.
The connectors are to be used to interface with existing line cards and future develop
cards. With careful routing and following the guidelines in this chapter, this topology
can run at a maximum speed of 33 MHz.
EX_CS4# Mezzanine Connector 1
EX_CS5# Mezzanine Connector 2
EX_CS6# Mezzanine Connector 3
Chip Select Signal Peripheral
Table 87. LEB Memory Size (LEB_SIZE) Strapping
LEB_SIZE
[23 : 21]
MMBAR
Size
# of CS
“+ 16 MB” mode
# of CS
“+ 32 MB” mode
000 0 MB None None
001 32 MB 2 1
010 64 MB 4 2
011 128 MB 8 4
1xx 256 MB 16 (See Note) 8
Note: Only 8 chip selects are supported; the other 8 are alias of the first 8 chip selects. Refer to the Utilizing
the Local Expansion Bus on the Intel® EP80579 Integrated Processor Product Line Application Note,
Document Number 321096 for details.

Intel EP80579 Specifications

General

Brand	Intel
Model	EP80579
Category	Computer Hardware
Language	English