EP4CE40 datasheet(242/488 Pages) ALTERA

242 / 488 page

8–78

Chapter 8: Configuration and Remote System Upgrades in Cyclone IV Devices

Remote System Upgrade

Cyclone IV Device Handbook,

May 2013

Altera Corporation

Volume 1

Table 8–25 lists the contents of previous state register 1 and previous state register 2 in

the status register. The status register bit in Table 8–25 shows the bit positions in a

3-bit register. The previous state register 1 and previous state register 2 have the same

bit definitions. The previous state register 1 reflects the current application

configuration and the previous state register 2 reflects the previous application

configuration.

If a capture is inappropriately done while capturing a previous state before the system

has entered remote update application configuration for the first time, a value outputs

from the shift register to indicate that the capture is incorrectly called.

Remote System Upgrade State Machine

The remote system upgrade control and update registers have identical bit

definitions, but serve different roles (Table 8–22 on page 8–75). While both registers

can only be updated when the device is loaded with a factory configuration image,

the update register writes are controlled by the user logic, and the control register

writes are controlled by the remote system upgrade state machine.

In factory configurations, the user logic should send the option bits (Cd_early and

Osc_int

), the configuration address, and watchdog timer settings for the next

application configuration bit to the update register. When the logic array

configuration reset (RU_nCONFIG) goes high, the remote system upgrade state machine

updates the control register with the contents of the update register and starts system

reconfiguration from the new application page.

1 To ensure the successful reconfiguration between the pages, assert the 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 8–26 lists the contents of the control register after such an event occurs for all

possible error or trigger conditions.

Table 8–25. Remote System Upgrade Previous State Register 1 and Previous State Register 2 Contents in Status

Status Register Bit

Definition

Description

nCONFIG

source

One-hot, active-high field that describes the reconfiguration source

that caused the Cyclone IV device to leave the previous application

configuration. If there is a tie, the higher bit order indicates

precedence. For example, if nCONFIG and remote system upgrade

nCONFIG

reach the reconfiguration state machine at the same time,

the nCONFIG precedes the remote system upgrade nCONFIG.

CRC error source

nSTATUS

source

User watchdog timer source

Remote system upgrade

nCONFIG

source

25:24

Master state machine

current state

The state of the master state machine during reconfiguration causes

the Cyclone IV device to leave the previous application configuration.

23:0

Boot address

The address used by the configuration scheme to load the previous

application configuration.

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