PLX Technology PEX 8311RDK, Справочник по аппаратуре

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PEX 8311RDK Hardware Reference Manual, Version 0.90
© 2005 PLX Technology, Inc. All rights reserved.
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3.2.1 SPI EEPROM
The SPI EEPROM (U2) is the Express Configuration EEPROM. This is largely used to control PCI
Express performance and is not normally required to bring up the PEX 8311. The SPI EEPROM (U2) can
also be used to pre-configure the on-chip 8K shared memory.
The SPI EEPROM (U2) is connected to an 8-pin DIP socket to allow removal and programming with
external PROM programmer if required. The EEPROM can also be programmed through the PEX 8311
using the utilities provided. A pull-up resistor (R4) on the EERDDATA ball produces a value of FFh if there
is no serial EEPROM installed.
The PEX 8311 supports up to 16 MB SPI serial EEPROM’s, utilizing 1, 2, or 3-byte addressing. The PEX
8311 automatically determines the appropriate addressing mode. The SPI operates at up to 25 MHz and
can directly interface with the PEX 8311. The Atmel AT25640 device as used in the PEX 8311RDK is
recommended. Other compatible 128-byte serial EEPROM’s include the Atmel AT25010A, Catalyst
CAT25C01, and ST Microelectronics M95010W.
The SPI EEPROM on the PEX 8311RDK is blank when shipped.
3.2.2 Microwire Serial EEPROM
The socketed 2Kbit Microwire serial EEPROM (U6) is the Local Configuration EEPROM and is used to
control local bus behavior and assign appropriate address ranges. It is connected directly to the PEX
8311 and provides the configuration data to initialize the device after the system reset is removed. The
EEPROM image is compatible with those of the PLX PCI 9x56 devices and may be loaded with those
images to speed development.
The Microwire EEPROM will be required for most designs to ensure that the correct address space
ranges are assigned. A pull-up on EEDI/EEDO (R36) ensures that the RDK will boot if a blank EEPROM
is installed. If no EEPROM is installed then a pull-down will be required on EEDI/EEDO (R39) to ensure
that the device boots correctly.