ep3c120f780c8nes Altera Corporation, ep3c120f780c8nes Datasheet - Page 357

• Manufacturer Part Number: ep3c120f780c8nes
• Description: Cyclone Iii Device Family
• Manufacturer: Altera Corporation

Altera Corporation-Preliminary
March 2007
The user watchdog timer is a counter that counts down from the initial
value loaded into the remote system upgrade control register by the
factory configuration. The counter is 29 bits wide and has a maximum
count value of 2
specify only the most significant 12 bits. The granularity of the timer
setting is 2
10-MHz internal oscillator.
the 10-MHz internal oscillator.
The user watchdog timer begins counting once the application
configuration enters device user mode. This timer must be periodically
reloaded or reset by the application configuration before the timer expires
by asserting RU_nRSTIMER. If the application configuration does not
reload the user watchdog timer before the count expires, a time-out signal
is generated by the remote system upgrade dedicated circuitry. The
timeout signal tells the remote system upgrade circuitry to set the user
watchdog timer status bit (Wd) in the remote system upgrade status
register and reconfigures the device by loading the factory configuration.
The user watchdog timer is not enabled during the configuration cycle of
the device. Errors during configuration are detected by the CRC engine.
Also, the timer is disabled for factory configurations. Functional errors
should not exist in the factory configuration since it is stored and
validated during production and is never updated remotely.
1
Interface Signals between Remote System Upgrade Circuitry
and Cyclone III Device Logic Array
The dedicated remote system upgrade circuitry drives (or receives) seven
signals to (or from) the Cyclone III device logic array. The device logic
array uses these signals to read and write the remote system upgrade
Note to
(1)
Table 12–10. 10-MHz Internal Oscillator Specifications
Minimum
These values are preliminary.
Table
5
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.
17
cycles. The cycle time is based on the frequency of the
12–10:
29
. When specifying the user watchdog timer value,
Typical
Remote System Upgrade With Cyclone III Devices
6.5
Table 12–10
Cyclone III Device Handbook, Volume 1
specifies the operating range of
Maximum
10
Note (1)
Units
MHz
12–17