Pico-communications E-14 Manuale Utente Scaricare il pdf (Pagina 11)

E‐14HardwareReferenceManual www.picocomputing.com PicoComputing,Inc.

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FlashMemory

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ThePicoE‐14comesequippedwithatleast64megabytesofFlashROM.TheFlashROMisdividedinto

512sectorsthatcanbeerasedindependently.MostofthespaceontheROMisreservedfortheuser.

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TheFlashROM’saddressbuscanbecontrolledbyeithertheTurboLoader

ortheFPGA,butnotboth.

Duringpower‐uporreboot,theTurboLoaderisincontroloftheFlashROMAddressbus.Atallother

timestheFPGAisincontroloftheaddressbus.

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Figure2

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TypicalFlashROMAllocationTable:

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Byteaddresses Description FlashSectors

0x00000000‐0x0000FFFF TupleDataandconfigurationmanagement 0

0x00010000‐0x0006FFFF PrimaryFPGAImage 1‐6

0x000A0000‐0x000FFFFF BackupFPGAImage 7‐12

0x000D0000‐0x0012FFFF SecondaryImageincludingbootloader 13‐19

0x00140000‐0x01FFFFFF OtherFPGAimages,executablesanddatafiles 20‐511

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TheFlashROMhasasimple,openfilesystemthatallowstheusertostoreFPGAimages,ELFbinary

files,orotherdata.TheprimaryimageisusedtoboottheFPGAinitially,andthebackupimageisonly

invokediftheprimaryimagefailstoloadcorrectly.ExecutablefilesareinELFformatandareloadedby

aloaderwithinthesecondaryimage.Theprimaryimagecaneitherloadthesecondaryimageorpause

forthePCtoaccessandmanagethefilesystem.

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Pico-communications E-14 Manuale Utente Pagina 11