Configuration & Testing
While in the factory configuration, the factory-configuration logic
performs the following operations:
■
■
■
Loads a remote update-control register to determine the page
address of the new application configuration
Determines whether to enable a user watchdog timer for the
application configuration
Determines what the watchdog timer setting should be if it is
enabled
The user watchdog timer is a counter that must be continually reset
within a specific amount of time in the user mode of an application
configuration to ensure that valid configuration occurred during a remote
update. Only valid application configurations designed for remote
update can reset the user watchdog timer in user mode. If a valid
application configuration does not reset the user watchdog timer in a
specific amount of time, the timer updates a status register and loads the
factory configuration. The user watchdog timer is automatically disabled
for factory configurations.
If an error occurs in loading the application configuration, the
configuration logic writes a status register to specify the cause of the error.
Once this occurs, the Stratix device automatically loads the factory
configuration, which reads the status register and determines the reason
for reconfiguration. Based on the reason, the factory configuration will
take appropriate steps and will write the remote update control register
to specify the next application configuration page to be loaded.
When the Stratix device successfully loads the application configuration,
it enters into user mode. The Stratix device then executes the main
application of the user. Intellectual property (IP), such as a Nios® (16-bit
ISA) and Nios® II (32-bit ISA) embedded processors, can help the Stratix
device determine when remote update is coming. The Nios embedded
processor or user logic receives incoming data, writes it to the
configuration device, and loads the factory configuration. The factory
configuration will read the remote update status register and determine
the valid application configuration to load. Figure 3–2 shows the Stratix
remote update. Figure 3–3 shows the transition diagram for remote
update mode.
Altera Corporation
July 2005
3–9
Stratix Device Handbook, Volume 1
ALTERA [ ALTERA CORPORATION ]
