CDPCLK4 datasheet(243/274 Pages) ALTERA

243 / 274 page

Chapter 9: Configuration, Design Security, and Remote System Upgrades in the Cyclone III Device Family

9–85

Remote System Upgrade

August 2012

Altera Corporation

Cyclone III Device Handbook

Volume 1

1 To ensure the successful reconfiguration between the pages, assert RU_nCONFIG signal

for a minimum of 250 ns. This is equivalent to strobing the reconfig input of the

ALTREMOTE_UPDATE megafunction high for a minimum of 250 ns.

If there is an error or reconfiguration trigger condition, the remote system upgrade

state machine directs the system to load a factory or application configuration (based

on mode and error condition) by setting the control register accordingly.

Table 9–30 lists the contents of the control register after such an event occurs for all

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.

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 229. When specifying the

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 217 cycles. The cycle time is based on the

frequency of the 10-MHz internal oscillator.

Table 9–31 lists the operating range of the 10-MHz internal oscillator.

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.

Table 9–30. Control Register Contents After an Error or Reconfiguration Trigger Condition

Reconfiguration

Error/Trigger

Control Register Setting In

Remote Update

nCONFIG

reset

All bits are 0

nSTATUS

error

All bits are 0

CORE triggered reconfiguration

Update register

CRC error

All bits are 0

Wd time out

All bits are 0

Table 9–31. 10-MHz Internal Oscillator Specifications

Minimum

Typical

Maximum

Unit

6.5

MHz

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