EP3C16F256I7N Altera, EP3C16F256I7N Datasheet - Page 247

• Manufacturer Part Number: EP3C16F256I7N
• Description: Cyclone III
• Manufacturer: Altera

Chapter 9: Configuration, Design Security, and Remote System Upgrades in the Cyclone III Device Family
Remote System Upgrade
© December 2009
1
Altera Corporation
Table 9–30
possible error or trigger conditions.
The remote system upgrade status register is updated by the dedicated error
monitoring circuitry after an error condition but before the factory configuration is
loaded.
Table 9–30. Control Register Contents After an Error or Reconfiguration Trigger Condition
User Watchdog Timer
The user watchdog timer prevents a faulty application configuration from stalling the
device indefinitely. The system uses the timer to detect functional errors after an
application configuration is successfully loaded into the Cyclone III device family.
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
user watchdog timer value, specify only the most significant 12 bits. Remote system
upgrade circuitry appends 17’b1000 to form the 29 bits value for the watchdog timer.
The granularity of the timer setting is 2
frequency of the 10-MHz internal oscillator.
Table 9–31
Table 9–31. 10-MHz Internal Oscillator Specifications
The user watchdog timer begins counting after 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
time-out 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.
To allow remote system upgrade dedicated circuitry to reset the watchdog timer, you
must assert the RU_nRSTIMER signal active for a minimum of 250 ns. This is
equivalent to strobing the reset_timer input of the ALTREMOTE_UPDATE
megafunction high for a minimum of 250 ns.
nCONFIG reset
nSTATUS error
CORE triggered reconfiguration
CRC error
Wd time out
Minimum
5
lists the contents of the control register after such an event occurs for all
lists the operating range of the 10-MHz internal oscillator.
Reconfiguration
Error/Trigger
Typical
6.5
17
cycles. The cycle time is based on the
All bits are 0
All bits are 0
Update register
All bits are 0
All bits are 0
Maximum
Control Register Setting In
10
Cyclone III Device Handbook, Volume 1
Remote Update
29
. When specifying the
MHz
Unit
9–87