EP4CE40 datasheet(222/488 Pages) ALTERA

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

Configuration

Cyclone IV Device Handbook,

May 2013

Altera Corporation

Volume 1

Use the ACTIVE_DISENGAGE instruction with the CONFIG_IO instruction to interrupt

configuration. Table 8–16 lists the sequence of instructions to use for various

CONFIG_IO

usage scenarios.

The CONFIG_IO instruction does not hold nSTATUS low until reconfiguration. You must

disengage the AS or AP configuration controller by issuing the ACTIVE_DISENGAGE and

ACTIVE_ENGAGE

instructions when active configuration is interrupted. You must issue

the ACTIVE_DISENGAGE instruction alone or prior to the CONFIG_IO instruction if the

JTAG_PROGRAM

instruction is to be issued later (Table 8–17). This puts the active

configuration controllers into the idle state. The active configuration controller is re-

engaged after user mode is reached through JTAG programming (Table 8–17).

1 While executing the CONFIG_IO instruction, all user I/Os are tri-stated.

If reconfiguration after interruption is performed using configuration modes (rather

than using JTAG_PROGRAM), it is not necessary to issue the ACTIVE_DISENGAGE

instruction prior to CONFIG_IO. You can start reconfiguration by either pulling nCONFIG

low for at least 500 ns or issuing the PULSE_NCONFIG instruction. If the

ACTIVE_DISENGAGE

instruction was issued and the JTAG_PROGRAM instruction fails to

enter user mode, you must issue the ACTIVE_ENGAGE instruction to reactivate the active

configuration controller. Issuing the ACTIVE_ENGAGE instruction also triggers

reconfiguration in configuration modes; therefore, it is not necessary to pull nCONFIG

low or issue the PULSE_NCONFIG instruction.

Table 8–16. JTAG CONFIG_IO (without JTAG_PROGRAM) Instruction Flows (1)

JTAG Instruction

Configuration Scheme and Current State of the Cyclone IV Device

Prior to User Mode

(Interrupting Configuration)

User Mode

Power Up

FPP

ACTIVE_DISENGAGE

—

CONFIG_IO

JTAG Boundary Scan

Instructions (no

JTAG_PROGRAM

)

—

ACTIVE_ENGAGE

R (2)

—

PULSE_NCONFIG

A (3)

—

Pulse nCONFIG pin

A (3)

—

JTAG TAP Reset

—

Notes to Table 8–16:

(1) You must execute “R” indicates that the instruction before the next instruction, “O” indicates the optional instruction, “A” indicates

that the instruction must be executed, and “NA” indicates that the instruction is not allowed in this mode.

(2) Required if you use ACTIVE_DISENGAGE.

(3) Neither of the instruction is required if you use ACTIVE_ENGAGE.

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