EP2AGX95EF29C6N Datasheet, PDF (340/380 Pages) Altera Corporation – Device Interfaces and Integration

9–54
Chapter 9: Configuration, Design Security, and Remote System Upgrades in Arria II Devices
Remote System Upgrade Mode
1 The user watchdog timer is automatically disabled for factory configurations. For
more information about the user watchdog timer, refer to “User Watchdog Timer” on
page 9–59.
If there is an error while loading the application configuration, the cause of the
reconfiguration is written by the dedicated circuitry to the remote system upgrade
status register. Actions that cause the remote system upgrade status register to be
written are:
■ nSTATUS driven low externally
■ Internal CRC error
■ User watchdog timer time-out
■ A configuration reset (logic array nCONFIG signal or external nCONFIG pin assertion
to low)
Arria II devices automatically load the factory configuration located at page address
zero. This user-designed factory configuration can read the remote system upgrade
status register to determine the reason for the reconfiguration. The factory
configuration then takes the appropriate error recovery steps and writes to the remote
system upgrade control register to determine the next application configuration to be
loaded.
When Arria II devices successfully load the application configuration, they enter into
user mode. In user mode, the soft logic (a Nios II processor or state machine and the
remote communication interface) assists the Arria II device in determining when a
remote system update is arriving. When a remote system update arrives, the soft logic
receives the incoming data, writes it to the configuration memory device, and triggers
the device to load the factory configuration. The factory configuration reads the
remote system upgrade status register and control register, determines the valid
application configuration to load, writes the remote system upgrade control register
accordingly, and initiates system reconfiguration.
Arria II Device Handbook Volume 1: Device Interfaces and Integration
July 2012 Altera Corporation