30 Altera Corporation
Board Components Nios Development Board Reference Manual, Cyclone Edition
Safe and User Configurations
The configuration controller can manage three separate Cyclone device
configurations: one configuration stored in the EPSC4 configuration
device, and two configurations stored in flash memory. These two
configurations stored in flash memory are conventionally referred to as
the safe configuration and the user configuration.
The configuration controller expects user configuration and safe
configuration files to be stored at fixed locations (offsets) in flash memory.
Table 10 on page 32 shows how the configuration controller expects flash
memory contents to be arranged.
1 A Nios reference design is pre-loaded into the safe-configuration
region of the flash memory. Altera recommends that users avoid
overwriting the safe configuration data.
If SW9 (Force Safe) is pressed, the configuration controller will ignore the
user-configuration and always configure the Cyclone device from the safe
configuration. This switch allows you to “escape” from the situation
where a valid-but-nonfunctional user configuration is present in flash
memory or the serial configuration device.
f
See the Nios Embedded Processor Software Development Reference Manual for
detailed information about downloading and relocating files using the
GERMS monitor.
Using Conventional Flash Memory
The Nios Development Board includes an 8 MByte flash memory device
(U5). See Table 9. It is divided into 128 individually-erasable 64K sectors.
This web-server design, and (more importantly) the on-board
configuration controller, makes certain assumptions about what–resides–
where in flash memory.
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