Interphase Tech 4538 - Manual (Page 81)

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4538 Hardware Reference Manual 59
2 4538 Power-Up Initialization
Overview
After power-up, the STARTUP code is executed. This code is written entirely in assembly
language and is the entry point after a power-up or a reset exception. STARTUP configures
the PowerQUICC II and several other critical hardware elements such as the SDRAM
memories. Once STARTUP is executed, code written in a high-level language such as “C”
is executed.
This chapter describes this STARTUP initialization.
N
OTE
The STARTUP source code is provided in the APP/ASM/STARTUP.ASM file.
PowerSpan Initialization
The PowerSpan is initialized by several different mechanisms.
During the power-up phase, the PowerSpan uses some of its I/O pins to determine its
Hardware Configuration Word (also called Power-up options in PowerSpan
documentation).
Then the PowerSpan initializes several of its internal registers by loading their values from
the I²C serial EEPROM. Among these registers, the PCI vendor and device identification,
the size of the PCI-to-Local windows, and the size and position of the first Local to PCI
window are initialized by the serial EEPROM.
The addresses in the PCI space of the PCI-to-Local windows are chosen by the PCI host
during its boot and programmed in the PCI configuration registers.
All the other initializations must be done either by the PowerSpan during its boot or by the
PCI host.
PowerSpan Hardware Configuration Word
On the board, this configuration is defined as follows:
• PB_ARB_EN=0: Disable PowerSpan arbiter for 60x local bus
• P1_ARB_EN=0: Disable PowerSpan arbiter for PCI 1 bus
• P2_ARB_EN=0: Disable PowerSpan arbiter for PCI 2 bus (no PCI 2 bus)
• PWRUP_PRI_PCI=0: PCI 1 is primary PCI bus
• P1_R64_EN=0: Disable PCI 1 REQ64