Altera Embedded Systems Development Kit, Cyclone III Edit Uživatelský manuál stáhnout pdf (Strana 50)

Altera Corporation Development Board Version 1.0.8–2

July 2010 Altera Embedded Systems Development Kit, Cyclone III Edition

Application Selector Details

Application Boot

Code

All applications which are loaded by the application selector must

contain a Nios II CPU whose reset address is set to CFI flash at offset 0x0.

For this reason, a generic bit of boot code is permanently programmed at

offset 0x0 in the CFI Flash as part of the factory recovery image. This boot

code is very small and only performs the following functions

■ Flushes the Nios II instruction cache

■ Flushes the Nios II instruction pipeline

■ Branches to offset 0x0240000

Offset 0x0240000 is where the application software image is located after

being loaded by the Application Selector, so when the FPGA is

reconfigured, the Nios II CPU executes this boot code, which branches to

the boot copier of the actual application software image, which then

copies the application to program memory, then runs the application.

1 The Application Selector relies on a feature of the configuration

controller in the MAXII device on the board. This feature allows

the Nios II CPU to issue a command to the configuration

controller telling it to reconfigure the FPGA from a specific

location in a parallel flash memory, such as the on-board CFI

flash. The way the Application Selector is able to reconfigure

itself with a new hardware image is by using Nios II to read the

hardware image from the SD Card, program it to some location

in CFI flash, then force the FPGA to reconfigure from that

location using the MAXII configuration controller.

Flash Hardware

Image Catalog

The CFI flash holds up to 10 of the most recently loaded application

hardware images to speed the load times of applications which are

loaded often. To keep track of which hardware images are stored in flash,

a flash image catalog is kept in CFI flash at offset 0x0020000. The

implementation details of this catalog are described in the Hardware

Image Caching section below.

Table 8–1. Memory Map of CFI Flash

Flash Size Flash Contents

0x0000000 - 0x001FFFF Application Boot Code

0x0020000 - 0x003FFFF HW Image Catalog

0x0040000 - 0x00FFFFF Unused

0x0100000 - 0x023FFFF Selector SW Image

0x0240000 - 0x1BFFFFF Application SW Image

0x1C00000 - 0x1FFFFFF Reserved

1 2 ... 45 46 47 48 49 50 51 52 53 54 55 ... 81 82

Komentáře k této Příručce

Žádné komentáře

Altera Embedded Systems Development Kit, Cyclone III Edit Uživatelský manuál Strana 50

Komentáře k této Příručce

Související produkty a manuály pro Měřící nástroje Altera Embedded Systems Development Kit, Cyclone III Edit