24538 Power-Up Initialization

Overview

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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.

NOTE

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

4538 Hardware Reference Manual

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