EP2S180F1020C4 Datasheet, PDF (681/768 Pages) Altera Corporation – Stratix II Device Handbook, Volume 1

Remote System Upgrades with Stratix II and Stratix II GX Devices
1 The user watchdog timer is disabled in factory configurations
and during the configuration cycle of the application
configuration. It is enabled after the application configuration
enters user mode.
Interface Signals between Remote System Upgrade Circuitry
and FPGA Logic Array
The dedicated remote system upgrade circuitry drives (or receives) seven
signals to (or from) the FPGA logic array. The FPGA logic array uses these
signals to read and write the remote system upgrade control, status, and
update registers using the remote system upgrade shift register. Table 8–8
lists each of these seven signals and describes their functionality.
Except for RU_nRSTIMER and RU_CAPTnUPDT, the logic array signals are
enabled for both remote and local update modes and for both factory and
application configurations. RU_nRSTIMER is only valid for application
configurations in remote update mode, since local update configurations
and factory configurations have the user watchdog timer disabled. When
RU_CAPTnUPDT is low, the device can write to the update register only
for factory configurations in remote update mode, since this is the only
case where the update register is written to by the user logic. When the
RU_nCONFIG signal goes high, the contents of the update register are
written into the control register for controlling the next configuration
cycle.
Table 8–8. Interface Signals between Remote System Upgrade Circuitry and FPGA Logic Array (Part 1
of 3)
Signal Name
RU_nRSTIMER
RU_nCONFIG
Signal Direction
Input to remote system
upgrade block (driven by
FPGA logic array)
Input to remote system
upgrade block (driven by
FPGA logic array)
Description
Request from the application configuration to reset the user
watchdog timer with its initial count. A falling edge of this signal
triggers a reset of the user watchdog timer.
When driven low, this signal triggers the device to reconfigure.
If asserted by the factory configuration in remote update
mode, the application configuration specified in the remote
update control register is loaded. If requested by the
application configuration in remote update mode, the factory
configuration is loaded.
In the local updated mode, the application configuration is
loaded whenever this signal is asserted.
Altera Corporation
January 2008
8–21
Stratix II Device Handbook, Volume 2